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  • LUNAR AND PLANETARY EXPLORATION  (715)
  • ASTROPHYSICS  (709)
  • 1985-1989  (1,424)
  • 1980-1984
  • 1965-1969
  • 1950-1954
  • 1985  (1,424)
Collection
Keywords
Years
  • 1985-1989  (1,424)
  • 1980-1984
  • 1965-1969
  • 1950-1954
Year
  • 1
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    Interplanetary shock phenomena beyond 1 AU (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Attention is given to spatial dependences exhibited by spacecraft measurements obtained between 1 and 30 AU, together with temporal variations occurring between solar activity cycle maxima and minima. At 1-3 AU radial distances, shocks develop in association with the corotating solar wind streams characterizing solar minimum and accelerate solar wind evolution with distance while heating the solar wind and generating waves and turbulence. At solar maximum, shocks are observed more frequently at 1 AU but still in association with transient solar events; acceleration leading to energetic storm particles is observed both within and beyond 1 AU. The superimposed effect of large numbers of intense shocks may be responsible for the solar cycle modulation of galactic cosmic rays.
    Keywords: ASTROPHYSICS
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  • 2
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    Nucleus studies of Comet Halley (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Early results from, and research initiatives warranted by, the earth-based observations of Halley's near-nucleus and related phenomena are reviewed. Where appropriate, this information is combined with spacecraft data obtained by the various flight projects. The basic objective is to gain a greater insight into the nature of the comet's nucleus and its environment.
    Keywords: ASTROPHYSICS
    Type: Advances in Space Research (ISSN 0273-1177); 5; 12, 1; 307-316
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  • 3
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    Preliminary results of the Giotto radio science experiment (1985)
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    Publication Date: 2011-08-19
    Description: Doppler and ranging measurements using the radio signal of the Giotto spacecraft were taken before, during, and after the encounter with Comet Halley on Mar. 13, 14, 1986. The spacecraft velocity was found to decrease by a total of 23.3 cm/s due to impacting gas and (primarily) dust in the cometary atmosphere. A preliminary dust production rate of 1000 kg/s is found to be consistent with this deceleration. Power spectra of the carrier phase fluctuations reveal an increase in level and a flattening of the spectrum just prior to encounter, presumably associated with the enhanced dust impact rate. Finally, simulated Doppler time profiles are computed using the radial dependence of plasma density observed by the Giotto in situ investigations. It is shown that the cometary electron content profile would have been clearly seen if a dual-frequency downlink radio configuration had been available at encounter.
    Keywords: ASTROPHYSICS
    Type: Advances in Space Research (ISSN 0273-1177); 5; 12, 1
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  • 4
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    A preliminary look at the dust in Comet Halley (1985)
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    Publication Date: 2011-08-19
    Description: Highlights of infrared observations of the dust are discussed and compared with first results from the space probes. An emission feature was detected at 3.4 microns; the 10 and 20 micron silicate features were well-observed; and far-infrared data out to 160 micron were obtained. Organic material seems to be abundant in grains and may explain the 3.4 micron emission. Calculations are presented for one example of organic material. A component of the grains may volatize at temperatures around 300 K.
    Keywords: ASTROPHYSICS
    Type: Advances in Space Research (ISSN 0273-1177); 5; 12, 1; 325-334
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  • 5
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    Cometary kilometric radio waves and plasma waves correlated with ion pick-up effect at Comet Halley (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Bow-shock movements at Comet Halley are inferred from the discrete spectra of the cometary kilometric radiation (30-195 kHz); the observed emissions can be interpreted as being generated and propagating from the moving shock. The shock motion is possibly associated with the time variation of the solar wind and cometary outgassing. It is concluded that these plasma wave phenomena are manifestations of ion pick-up processes, which occur even in a remote region 7 million to 10 million km from the cometary nucleus.
    Keywords: ASTROPHYSICS
    Type: Advances in Space Research (ISSN 0273-1177); 5; 12, 1; 83-88
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  • 6
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    The Venus ionosphere (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Physical properties of the Venus ionosphere obtained by experiments on the US Pioneer Venus and the Soviet Venera missions are presented in the form of models suitable for inclusion in the Venus International Reference Atmosphere. The models comprise electron density (from 120 km), electron and ion temperatures, and relative ion abundance in the altitude range from 150 km to 1000 km for solar zenith angles from 0 to 180 deg. In addition, information on ion transport velocities, ionopause altitudes, and magnetic field characteristics of the Venus ionosphere, are presented in tabular or graphical form. Also discussed is the solar control of the physical properties of the Venus ionosphere.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Advances in Space Research (ISSN 0273-1177); 5; 11, 1
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  • 7
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    Particulate matter in the Venus atmosphere (1985)
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    Publication Date: 2011-08-19
    Description: The paper presents a summary of the data currently available (June 1984) describing the planet-enshrouding particulate matter in the Venus atmosphere. A description and discussion of the state of knowledge of the Venus clouds and hazes precedes the tables and plots. The tabular material includes a precis of upper haze and cloud-top properties, parameters for model-size distributions for particles and particulate layers, and columnar masses and mass loadings.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Advances in Space Research (ISSN 0273-1177); 5; 11, 1
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  • 8
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    Models of Venus neutral upper atmosphere - Structure and composition (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Models of the Venus neutral upper atmosphere, based on both in situ and remote sensing measurements, are provided for the height interval from 100 to 3500 km. The general approach in model formulation was to divide the atmosphere into three regions: 100-150 km, 150-250 km, and 250-3500 km. Boundary conditions at 150 km are consistent with both drag and mass spectrometer measurements. A paramount consideration was to keep the models simple enough to be used conveniently. Available observations are reviewed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Advances in Space Research (ISSN 0273-1177); 5; 11, 1
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  • 9
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    CNO isotopes in red giant stars (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Observational data on CNO abundance ratios in red giants and the interstellar medium (ISM) are analyzed for the implications for the production and distribution of CNO nuclides. The data included isotope abundance measurements for the atmospheres and recent ejecta of cool giants, e.g., carbon stars, S-type stars, red supergiants and oxygen-rich giants beginning an ascent of the giant branch. The contribution of intermediate-mass stars to galactic nuclear evolution is discussed after comparing red giant abundances with ISM abundances, particularly the isotopes O-16, -17 and -18. The O-12/O-18 ratios of red giants are distinctly different from those in interstellar molecular clouds. The CNO values also vary widely from the values found in the solar system.
    Keywords: ASTROPHYSICS
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  • 10
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    CNO abundances in novae ejecta (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Isotope production, particularly CNO, which are enhanced in novae events and the interstellar medium (ISM) by novae are discussed in terms of emission-line data taken a few weeks after novae events. The emission-line abundances emerge only after the fading of absorption spectrum, and are also detectable in thin shells which sometimes, though rarely, form after novae. CNO abundances in these shells are equivalent to those observed in fading novae, with CNO/H ratios being 100 times solar values. Possible heavy element production pathways in the events and their shrinking are discussed, along with observation techniques for detecting CNO isotopes through absorption data on atomic transitions in novae ejecta and the ISM.
    Keywords: ASTROPHYSICS
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  • 11
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    An analysis of IRAS' solar system dust bands (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Measurements of longitudinal variations in the brightness and in the latitude of the solar system dust bands recently discovered by IRAS will determine the orbital elements of the particles involved and may discriminate between cometary and asteroidal models of the origin of these bands. The expected variations for bands of dust particles with common orbital elements and small eccentricity and inclination are calculated as functions of semimajor axis.
    Keywords: ASTROPHYSICS
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  • 12
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    Mass input into and output from the meteoritic complex (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The consequences which arise from the mutual collisions occurring between interplanetary meteoroids, the Poynting-Robertson (PR) effect and the radiation pressure ejection of small meteoroids are examined. The size distribution and flux of micrometeoroids at 1 AU are derived and the dependence of spatial density on distance from the sun is established. The following conclusions are made: (1) the lifetimes of meteoroids with masses approximately greater than 0.00001 g are dominated by catastrophic collisions; (2) after bering crushed by collisions, 70 to 85 percent of this mass will be in the form of zodiacal light particles (with masses in the range of 10 to the -10th g to 10 to the -5th g) which will in part be transported by the PR effect towards the sun where they will evaporate; (3) the 15 to 30 percent of the collisional fragments which have masses approximately less than 10 to the -10th g will, for the most part, be injected into hyperbolic orbits by radiation pressure.
    Keywords: ASTROPHYSICS
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  • 13
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    Selection effects against small comets (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Everhart's (1967) formulation is used to determine the correlation between the probability of discovering a comet and the size of its nuclear radius. The analysis is concentrated on comets that are not more than two or three hundred meters in diameter; hence, heliocentric variations in cometary brightness can be neglected. The effect of cometary physical decay is also considered, and a strong observational bias against the detection of small active comets is found. The following three factors are involved: (1) small comets must pass closer to the earth than large comets in order to be detected, (2) the resulting higher angular velocity for nearby comets leads to a decrease in the time available to discover a small comet, and (3) small comets physically decay and vanish faster than do large comets.
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  • 14
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    The interplanetary micrometeoroid flux and lunar primary and secondary microcraters (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: It is proposed that considerable care is required to properly interpret either spacecraft in situ data or lunar crater data as well as near-earth data; in the case of the former, complications may arise which may be attributed to secondary lunar ejecta impacts, in the latter, they may result from impacting earth-orbiting debris. Experimental evidence suggests that most impact pits on lunar rocks with pit diameters smaller than 7 micrometers have been generated by lunar secondary ejecta impacts and not by primary meteoroid impacts. It is also found that lunar crater production rates are more accurate when deduced from meteoroid space experiments and not from solar flare track ages. It is concluded that in so far as all of the above qualifications are taken into account, a self-consistent meteoroid flux versus mass distribution is obtained.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 15
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    IRAS observations of the interplanetary dust emission (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The Infrared Astronomical Satellite (IRAS) has completed a sensitive, highly redundant survey of the full sky in four broad photometric bands at 12, 25, 60, and 100 micrometers wavelength. The survey measured interplanetary dust emission over elongation angle ranging from 60 to 120 degrees. Bright emission from the main cloud is consistent with optically thin blackbody emission. The grains are evidently quite black, with an 'apparent albedo' of about 0.07. The data show clear evidence for deviation of the dust symmetry surface from the ecliptic plane. Surprising bands of emission were discovered near the ecliptic plane and about ten degrees on either side of it. The heliocentric distance of this material, suggested to be asteroidal in origin, is inferred to be about 2.5 AU from both color temperature and parallax measurements.
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  • 16
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    Large and small scale structures of molecular clouds in the Taurus Perseus complex (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The gaseous components studied in H I and OH absorption against the extragalactic radiosources 3C123 and 3C111 are found to be the low-density edges of condensations of a few 100 solar masses. The densest part of one of these condensations has a structure similar to that found in other dark clouds: it is fragmented into several cores of a few solar masses, with an orbital velocity dispersion of about 2 km/s. In turn, the extended low-density layer, optically thick in CO (2-1), is not a common feature. It depends on the ambient UV field, but the dust temperature in the core may control its existence. Even more critically; it is found that the lower is the dust temperature, the less massive is the core and the more extended is the envelope around it, for a given total mass in a given external pressure.
    Keywords: ASTROPHYSICS
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  • 17
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    Cepheid variables as extra-galactic distance indicators (1985)
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    Publication Date: 2011-08-19
    Description: The role of Cepheid variables in establishing the inner distance scale to nearby galaxies is discussed. Emphasis is placed on the necessity for broad wavelength coverage in attempting to account for metallicity differences and reddening internal to the parent galaxies. In addition linear detectors are essential in minimizing the effects of any unresolved background contribution to the photometry. Recent infrared observations of Cepheids in Local Group galaxies are surveyed and all published data on extra galactic Cepheids are presented for convenient access.
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  • 18
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    The 50 millisecond pulsar in the Large Magellanic Cloud and the X-ray pulse emission mechanism (1985)
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    Publication Date: 2011-08-19
    Keywords: ASTROPHYSICS
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  • 19
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    Interstellar clouds - From a dynamical perspective on their chemistry (1985)
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    Publication Date: 2011-08-19
    Description: The possibility is examined that in the course of its dynamical evolution, a single mass of interstellar gas would exhibit properties of diffuse clouds, dense clouds and finally also of clouds perturbed by shocks or intense UV or X-ray radiation generated by a star of its own creation. This concept provides a common thread through the bewildering diversity of physical and chemical compositional properties shown by interstellar clouds. From this perspective, instead of being static objects, interstellar clouds are possibly incessantly evolving from initially diffuse to later dense state and then to star formation which ultimately restructures or disperses the remaining cloud material to begin the whole evolutionary process once again. Based on a simplified study of interstellar chemistry from a dynamical perspective, the ideas are presented as an heuristic: to encourage thought on the future direction of molecular astrophysics and the need to consider the chemical behavior of interstellar clouds in conjunction with, rather than in isolation from, their dynamical behavior. A physical basis must be sought for the semiempirical temperature formula which has been given a critical role in the collapse of diffuse clouds. Self-shielding effects in the chemistry of CO were neglected and this drawback should be removed; the ability of the model to explain the fractional abundances of more complex molecules, such as cyanopolyynes, should be examined.
    Keywords: ASTROPHYSICS
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  • 20
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    Cometary comae (1985)
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    Publication Date: 2011-08-19
    Description: The basis of our knowledge about the structure and composition of a comet nucleus is examined. Such knowledge is inferred from observations of the cometary atmosphere (coma). However, photodissociation, photoionization, and chemistry destroy the mother molecules evaporating from the nucleus. To extract the primary information, the chemical kinetics and the physics of the coma are modeled with a computer and the results are compared with coma observations. The physics and chemistry for a dust free coma are described taking into account energy balance, multi-fluid flow for fast atomic and molecular hydrogen and the bulk fluid, and the transition from a collision dominated inner region to the free molecular flow outer region. Special attention is paid to the molecular data requirements for the current modeld and for extended models which will include solar wind interaction and dust. Such models are an important tool in support of the Giotto mission to Halley's comet, in the analysis and interpretation of coma observations, and in the understanding of the earliest history of the solar system.
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  • 21
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    Assisting extrasolar planetary detection through the determination of stellar space orientations (1985)
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    Publication Date: 2011-08-19
    Description: Various methods outlined for indirect planetary detection would greatly benefit (in some cases require) the determination of the planetary orbital plane, which is theoretically equivalent to the stellar equatorial plane. Determining the stellar space orientation, therefore, would greatly benefit extrasolar planetary detection. Stellar rotation periods determined from short-term variations in Ca II H and K sunspot emission are utilized together with both stellar radii measurements and Doppler-broadened spectral line profiles to get the stellar inclination to the line of sight. The clocklike on-the-plane-of-the-sky component determination utilizes the concentration of sunspot-associated plage areas at central stellar latitudes when viewed in Ca II H or K emission. One can perform Ca II H and K emission speckle interferometry to measure the clocklike angle of this stellar Ca II H and K emission band, modeling it as an elliptical intensity distribution. Both components should be determinable to within 10 deg for at least the resolvable fifth magnitude stars.
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  • 22
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    Problems with interpreting the radio emission from hot stars (1985)
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    Publication Date: 2011-08-19
    Description: Problems in hot star radio emission interpretation due to radio flux source and other modeling assumptions are examined. An upper limit constraint on the value of the mass loss rate divided by the constant wind velocity is imposed by assuming that the outflow is due to bremsstrahlung in a spherically symmetric wind with the stationary photosphere visible at 4500 A, and by the need for it to be less than the luminosity divided by c. The constraints are satisfied for the deduced values for OB supergiants, and to some extent for early 0 stars, but not for Wolf-Rayet stars, due to mass loss rates excessive by a factor of 10. It is suggested that the problem can be solved by postulating that part of the radio flux from Wolf-Rayet stars is due to processes in a low-density magnetized plasma.
    Keywords: ASTROPHYSICS
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  • 23
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    Dynamical evolution of the Oort cloud (1985)
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    Publication Date: 2011-08-19
    Description: New studies of the dynamical evolution of cometary orbits in the Oort cloud are made using a revised version of Weissman's (1982) Monte Carlo simulation model, which more accurately mimics the perturbation of comets by the giant planets. It is shown that perturbations by Saturn and Jupiter provide a substantial barrier to the diffusion of cometary perihelia into the inner solar system. Perturbations by Uranus and Neptune are rarely great enough to remove comets from the Oort cloud, but do serve to scatter the comets in the cloud in initial energy. The new model gives a population of 1.8 to 2.1 x 10 to the 12th comets for the present-day Oort cloud, and a mass of 7 to 8 earth masses. Perturbation of the Oort cloud by giant molecular clouds in the galaxy is discussed, as is evidence for a massive 'inner Oort cloud' internal to the observed one. The possibility of an unseen solar companion orbiting in the Oort cloud and causing periodic comet showers is shown to be dynamically plausible but unlikely, based on the observed cratering rate on the earth and moon.
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  • 24
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    Energy conversion processes in the outer planets (1985)
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    Publication Date: 2011-08-19
    Description: Energy conversion processes which are potentially important in the outer planets at pressures greater than obut 0.1 bar are reviewed. Generation of buoyancy contrasts by condensation of various constituents is discussed with emphasis on the possible significance of phase changes in substances such as Si and Mg compounds at deep levels. It is demonstrated that, in the absence of nonequilibrium thermodynamic processes, strong kinetic energy generation must accompany the transport of heat out of the high temperature planetary interiors. The possibly dominant role of lagged parahydrogen conversion in the convective transport of heat at levels where T is less than 300 K is discussed. Measurements which may ultimately contribute to a better understanding of energy conversion processes are summarized.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 25
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    Photochemistry and clouds of Jupiter, Saturn and Uranus (1985)
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    Publication Date: 2011-08-19
    Description: Photochemistry of ammonia, methane, phosphine, hydrogen sulfide, methylamine, hydrogen cyanide and carbon monoxide in the atmospheres of Jupiter, Saturn and Uranus is discussed. Condensation of ammonia, ammonium hydrosulfide, water, methane, ethane and acetylene below and near the tropopause of these planets is formulated. Whenever necessary, new calculations are included. Candidates for the upper atmospheric hazes, and the reddish-brown chromosphore in the clouds of Jupiter and Saturn are discussed.
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  • 26
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    A new emission feature in IRAS spectra and the polycyclic aromatic hydrocarbon spectrum (1985)
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    Publication Date: 2011-08-19
    Description: IRAS spectra of those sources which show strong 7.7 and 11.3 micron emission features also show a plateau of emission extending from 11.3 to about 13.0 microns. Like the 11.3 micron feature, this new feature is attributed to the CH out-of-plane bending mode in polycyclic aromatic hydrocarbons (PAHs). Its discovery reinforces the identification of the 'unidentified infrared emission features' as emission from PAHs. The wavelength of this new feature suggests that interstellar PAHs are not as partially hydrogenated as hitherto thought. It also constrains their molecular structure.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 299; L93-L97
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  • 27
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    Near-infrared mapping of ARP 299 (IC 694-NGC 3690) - Colliding galaxies unveiled (1985)
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    Publication Date: 2011-08-19
    Description: Near-infrared maps and multicolor photometry of the interacting galaxies IC 694 and NGC 3690 which form Arp 299 (= Markarian 171) are presented. These data reveal for the first time the distribution of nuclei and old red stars in a cataclysmically interacting system. The nuclei are considerably offset from the visual centroids of the galaxies but not from the mass centroids. The near-infrared colors of the most active regions are strongly affected by extinction, emission form hot dust, and bremsstrahlung. Near-infrared emission is also identified with secondary regions of star formation, probably resulting from the galaxies' interaction.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 299; 896-904
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  • 28
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    Mars missions and bases - A recent look (1985)
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    Publication Date: 2011-08-19
    Description: This paper discusses some of the key options for Mars programs, missions, bases, elements, and systems. Program and mission options include Mars flyby, orbiting, and landing missions; they include near-term 'sortie' missions, and later, longer-duration Mars-base missions. Key program and mission parameters include the mix of manned/unmanned elements, the number and types of space vehicles used, types of science done, trajectory options and implications launch timing and schedules, etc. The key mission parameters strongly affect the nature, sizing, and quantity of earth-to-orbit (ETO) vehicles. On-orbit assembly of space vehicles (SVs) is also an important related consideration. The potential degree of utilization of the Space Station (SS) and other then-existing elements is a key question, and several possibilities are discussed in this paper. Several configurations of SVs are provided. Several options are identified for the Mars base infra-structure, and parametric data is shown for buildup of bases as a function of mission and vehicle type. Technologies required for the missions are also discussed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 29
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    Molecular cloud evolution and star formation (1985)
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    Publication Date: 2011-08-19
    Description: The present state of knowledge of the relationship between molecular clouds and young stars is reviewed. The determination of physical parameters from molecular line observations is summarized, and evidence for fragmentation of molecular clouds is discussed. Hierarchical fragmentation is reviewed, minimum fragment scales are derived, and the stability against fragmentation of both spherically and anisotropically collapsing clouds is discussed. Observational evidence for high-velocity flows in clouds is summarized, and the effects of winds from pre-main sequence stars on molecular gas are discussed. The triggering of cloud collapse by enhanced pressure is addressed, as is the formation of dense shells by spherical outflows and their subsequent breakup. A model for low-mass star formation is presented, and constraints on star formation from the initial mass function are examined. The properties of giant molecular clouds and massive star formation are described. The implications of magnetic fields for cloud evolution and star formation are addressed.
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  • 30
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    Far-infrared and submillimeter photometry of evolved stars (1985)
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    Publication Date: 2011-08-19
    Description: Broad-band photometric observations at far infrared and submillimeter wavelengths (lambda is greater than 30 microns and less than 1) provide a unique probe of circumstellar shells in evolved objects and of the mass loss processes which produce them. The problems which these observations explore include: dust properties and dust-to-gas ratios in the outflowing material, the mass and structure of the circumstellar shell, and the pumping mechanism for maser emission. This contribution reviews the early work in this still largely unexploited field and reports results in each of the areas listed above. The dramatic advances forthcoming in this area from the IRAS satellite are previewed along with further progress which will come from the next generation of infrared and submillimeter telescopes.
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    Mass loss from red giants - Infrared spectroscopy (1985)
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    Publication Date: 2011-08-19
    Description: A discussion is presented of IR spectroscopy, particularly high-resolution spectroscopy in the approximately 1-20 micron band, as it impacts the study of circumstellar envelopes. The molecular bands within this region contain an enormous amount of information, especially when observed with sufficient resolution to obtain kinematic information. In a single spectrum, it is possible to resolve lines from up to 50 different rotational/vibrational levels of a given molecule and to detect several different isotopic variants. When high resolution techniques are combined with mapping techniques and/or time sequence observations of variable stars, the resulting information can paint a very detailed picture of the mass-loss phenomenon. To date, near-IR observations have been made of 20 molecular species. CO is the most widely observed molecule and useful information has been gleaned from the observed rotational excitation, kinematics, time variability and spatial structure of its lines. Examples of different observing techniques are discussed in the following sections.
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    The infrared characteristics of circumstellar silicate grains (1985)
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    Publication Date: 2011-08-19
    Description: A theoretical study of the infrared emission from circumstellar shells around late-type giants is made, with the aim of deriving the infrared characteristics of the silicate grains condensing in these shells. A large grid of models has been compared with observations of optically visible Miras, IRC sources and OH/IR stars. From fitting the observed relation between the color temperature and the strength of the 10-micron feature, it is concluded that the ratio of the 3.5 to 10-micron absorption efficiencies of the dust is about 0.25, a factor of 2 less than a previous determination. Detailed modeling of the 2 to 13-micron spectrum of OH 26.5 + 0.6, IRC + 10011 and R Cas yielded a similar ratio. These detailed models also show that the shape of the 10-micron feature, particularly around 8 and 13 microns, varies from source to source. The derived 10-micron feature is narrower for larger dust column densities. These observed differences in the intrinsic shape of the 10-micron feature are not due to differences in size of the condensing particles. Probably they are related to structural or compositional differences in the condensing silicates.
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    Lava tubes - Potential shelters for habitats (1985)
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    Publication Date: 2011-08-19
    Description: Natural caverns occur on the moon in the form of 'lava tubes', which are the drained conduits of underground lava rivers. The inside dimensions of these tubes measure tens to hundreds of meters, and their roofs are expected to be thicker than 10 meters. Consequently, lava tube interiors offer an environment that is naturally protected from the hazards of radiation and meteorite impact. Further, constant, relatively benign temperatures of -20 C prevail. These are extremely favorable environmental conditions for human activities and industrial operations. Significant operational, technological, and economical benefits might result if a lunar base were constructed inside a lava tube.
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    Protostellar angular momentum transport by spiral density waves (1985)
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    Publication Date: 2011-08-19
    Description: The application of rotational stability criteria to a specific model of star formation leads to the conclusion that the growth of stellar angular momentum is limited by its transfer to the disk. Excess accreted angular momentum can be transferred by torques connected with spiral density waves induced by even a slight protostellar triaxiality. In addition, viscous damping of the density waves is likely to cause the excess angular momentum to be deposited within a small region close to the protostar. Thus, it would be appropriate to treat that part of the growing protostellar disk beyond the outer Lindblad resonance as an accretion disk with a torque applied to its inner edge. It is noted that this situation is directly relevant to certain models of the evolution of the protosun and solar nebula.
    Keywords: ASTROPHYSICS
    Type: Icarus (ISSN 0019-1035); 64; 435-447
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    The plasma regime at comet Giacobini-Zinner (1985)
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    Publication Date: 2011-08-19
    Description: The paper reviews results on the plasma regime at Comet Giacobini-Zinner obtained by the International Cometary Explorer. The observations are consistent with the existence of a weak shock which may be pulsating, but do not exclude the suggestion that the shock, though present around the subsolar point, is an the process of decaying to a wave on the flanks. 'The pick-up' of cometary ions leads to ion cyclotron, mirror, beam, and electrostatic instabilities which cause strong turbulence in the inner coma.
    Keywords: ASTROPHYSICS
    Type: Advances in Space Research (ISSN 0273-1177); 5; 12, 1
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    Solar and thermal radiation in the Venus atmosphere (1985)
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    Publication Date: 2011-08-19
    Description: Attention is given to the solar and thermal radiation fields of Venus. Direct measurements and the results of numerical models based on direct measurements are presented. Radiation outside the atmosphere is considered with emphasis placed on global energy budget parameters, spectral and angular dependences, spatial distribution, and temporal variations of solar and thermal radiation. Radiation fluxes inside the atmosphere below 90 km are also considered with attention given to the solar flux at the surface, solar and thermal radiation fluxes from 100 km to the surface, and radiative heating and cooling below 100 km.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Advances in Space Research (ISSN 0273-1177); 5; 11, 1
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    Models of the structure of the atmosphere of Venus from the surface to 100 kilometers altitude (1985)
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    Publication Date: 2011-08-19
    Description: From a critical comparison and synthesis of data from the four Pioneer Venus Probes, the Pioneer Venus Orbiter, and the Venera 10, 12, and 13 landers, models of the lower and middle atmosphere of Venus are derived. The models are consistent with the data sets within the measurement uncertainties and established variability of the atmosphere. The models represent the observed variations of state properties with latitude, and preserve the observed static stability. The rationale and the approach used to derive the models are discussed, and the remaining uncertainties are estimated.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Advances in Space Research (ISSN 0273-1177); 5; 11, 1
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    Atmospheric circulation of Venus (1985)
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    Publication Date: 2011-08-19
    Description: Observational data of Venus are utilized to study rotational effects on atmospheric circulations. The high surface temperature and planetary-scale turbulent motion at cloud tops, and the relation between energy and momentum budget are examined. The limited amount of data available on the vertical and horizontal distribution of net radiative heating, the zonal wind structure, and waves affects the study of the temperature and motion on Venus. The limitations of the scaling analysis used to estimate the properties of the circulation as regards the cyclostrophic balance, the extent of the Hadley circulation, large-scale wave transport, vertical propagation of waves, convection, and turbulence are considered. Hypotheses concerned with the deep, cloud-level, and upper atmospheres of Venus are proposed. Future research in the areas of propagating planetary- scale waves, zonal flow and planetary-scale wave instability processes, and convection is suggested.
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    Ammonia in the hot galactic centre cloud G 1.6-0.025 (1985)
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    Publication Date: 2011-08-19
    Description: As part of an extensive southern survey of interstellar NH3 with the Parkes 64-m radio telescope (with a beamwidth of 81 arcsec), the (1,1), (2,2), and (3,3) transitions have been observed towards the galactic centre molecular cloud Gl.6-0.025. The cloud has an overall size of 10 arcmin, and contains several concentrations with differing velocities. It has several features also observed in other galactic centre clouds, e.g. high optical depths and kinetic temperatures above 50 K.
    Keywords: ASTROPHYSICS
    Type: Astronomical Society of Australia, Proceedings (ISSN 0066-9997); 6; 2, 19
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  • 40
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    The use of radar and visual observations to characterize the surface structure of the planet Mercury (1985)
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    Publication Date: 2011-08-19
    Description: An analysis is conducted of available topographic profiles and scattering parameters derived from earth-based S- and X-band radar observations of Mercury, in order to determine the nature and origin of regional surface variations and structures that are typical of the planet. Attention is given to the proposal that intercrater plains on Mercury formed from extensive volcanic flooding during bombardment, so that most craters were formed on a partially molten surface and were thus obliterated, together with previously formed tectonic features.
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    Advanced geologic exploration supported by a lunar base - A traverse across the Imbrium-Procellarum region of the moon (1985)
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    Publication Date: 2011-08-19
    Description: An example of extended traverse of a lunar region, the Imbrium-Procellarum, for the purpose of geological exploration is described. The necessary field support is discussed, including transportation and logistical support, analytical instrumentation, and field equipment. The various sites of special geological interest in the region are mentioned individually in the order in which they would be visited, indicating what questions are of particular scientific interest at each site.
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  • 42
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    Mass extinctions and cosmic collisions - A lunar test (1985)
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    Publication Date: 2011-08-19
    Description: The possibility has been considered that some or all major mass extinctions in the geologic record of earth are caused by the collision of massive, cosmic objects. Thus, it has been proposed that the unusual concentration of siderophile elements in strata at which the boundary between the Cretaceous (K) and Tertiary (T) geologic time periods has been placed must represent the remnants of a gigantic meteorite. However, a large 65-m.y.-old crater which could have been the result of the impact of this meteorite is not presently known on earth. One approach to evaluate the merits of the collisional hypothesis considered is based on the study of the probability of collision between a cosmic object of a suitable size and the earth. As moon and earth were subject to the same bombardment history and the preservation of craters on the moon is much better than on earth, a consideration of the lunar cratering record may provide crucial information.
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    Saturn's rings - Particle size distributions for thin layer model (1985)
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    Publication Date: 2011-08-19
    Description: A model incorporating limited interaction between the incident energy and particles in the ring is considered which appears to be consistent with the multiple scattering process in Saturn's rings. The model allows for the small physical thickness of the rings and can be used to relate Voyager 1 observations of 3.6- and 13-cm wavelength microwave scatter from the rings to the ring particle size distribution function for particles with radii ranging from 0.001 to 20 m. This limited-scatter model yields solutions for particle size distribution functions for eight regions in the rings, which exhibit approximately inverse-cubic power-law behavior.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 64; 531-548
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  • 44
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    A calculation of the Rosseland mean opacity of dust grains in primordial solar system nebulae (1985)
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    Publication Date: 2011-08-19
    Description: The Rosseland mean opacity owing to grains was calculated as a function of temperature and density for nebulae having solar elemental abundances. The values of the mean opacity were evaluated with a generalized formulation allowing for anisotropic scattering. The values of the mean opacity do not depend sensitively on the choice of the particle size distribution function, provided that there are few particles having sizes in excess of several tens of microns. The results indicate that thermal convection in primordial nebulae occurs over broader ranges of altitudes at low temperatures than at high temperatures, and for size distributions for which extensive aggregation has not yet occurred.
    Keywords: ASTROPHYSICS
    Type: Icarus (ISSN 0019-1035); 64; 471-492
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  • 45
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    Supersonic meteorology of Io - Sublimation-driven flow of SO2 (1985)
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    Publication Date: 2011-08-19
    Description: The horizontal flow of SO2 gas from the day side to the night side of IO is calculated on the basis of a hydrodynamic model. The flow speed is found to be supersonic for all realistic values of the parameters. The surface pressure follows the frost vapor pressure within a factor of 2 in spite of day-night pressure ratios of 10,000 or more. Atmospheric temperature is generally below the surface temperature due to decompression in the expanding flow. The greatest sensitivity of the solution is connected with the frost temperature at the subsolar point. The quantities that involve the mass of the atmosphere (density, pressure, mass transport, and condensation rate) all vary as the vapor pressure of the frost, which is a sensitive function of frost temperature.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 64; 375-390
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  • 46
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    Diagnostics of solar and astrophysical plasmas - Dependent on autoionization phenomena (1985)
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    Publication Date: 2011-08-19
    Description: The application of autoionization calculations to problems in solar and astrophysical plasma diagnostics is discussed. Attention is given to space plasmas having high spectral resolution, particularly in the wavelength region between about 300 and 1100 A. It is shown that atomic resonance data can be used to calculate many of the spectral line intensities in solar plasmas in order to obtain information concerning the physical properties of the emitting gas, including temperature, density, ionization balance, and atmospheric structure and dynamics. Recent spectral observations of nonsolar plasmas are also discussed. A list of the major high-resolution astrophysical plasma spectrometers and spectrographs is provided.
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    Empirical model of the composition of the Venus ionosphere Repeatable characteristics and key features not modeled (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: In-situ measurements of positive ion composition of the ionosphere of Venus are combined in an empirical model which is a key element for the Venus International Reference Atmosphere (VIRA) model. The ion data are obtained from the Pioneer Venus Orbiter Ion Mass Spectrometer (OIMS) which obtained daily measurements beginning in December 1978 and extending to July 1980 when the uncontrolled rise of satellite periapsis height precluded further measurements in the main body of the ionosphere. For this period, measurements of 12 ion species are sorted into altitude and local time bins with altitude extending from 150 to 1000 km. The model results exhibit the appreciable nightside ionosphere found at Venus, the dominance of atomic oxygen ions in the dayside upper ionosphere and the increase in prominence of atomic oxygen and deuterium ions on the nightside. Short term variations, such as the abrupt changes observed in the ionopause, cannot be represented in the model.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Advances in Space Research (ISSN 0273-1177); 5; 9, 19
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  • 48
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    Thermal net flux measurements on the Pioneer Venus entry probes (1985)
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    Publication Date: 2011-08-19
    Description: Corrected thermal net (upward minus downward flux) radiation data from four Pioneer Venus probes at latitudes of 4 deg and 60 deg N, and 27 deg and 31 deg S, are presented. Comparisons of these fluxes with radiative transfer calculations were interpreted in terms of cloud properties and the global distribution of water vapor in the lower atmosphere of Venus. The presence of an as yet undetected source of IR opacity is implied by the fluxes in the upper cloud range. It was also shown that beneath the clouds the fluxes at a given altitude increase with latitude, suggesting greater IR cooling below the clouds at high latitudes and a decrease of the water vapor mixing ratios toward the equator.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Advances in Space Research (ISSN 0273-1177); 5; 9, 19
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    The thermal release of Hg from chondrites and their thermal histories (1985)
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    Publication Date: 2011-08-19
    Description: A quantitative treatment and implications of isothermal and linear heating data on Hg in meteorites are given as a sequel to a more qualitative analysis of meteorite thermal histories (Reed and Jovanovic, 1968). Studies of Hg in terrestrial metamorphic rocks establish that thermal events to which meteorites were subjected fall in the same temperature range, of 400-900 C, as exists during terrestrial metamorphism. Hg diffusion parameters based on data from the linear and isothermal heating experiments are calculated. The conclusions are: (1) Meteorites experienced thermal events of the same magnitude as those measured by primarily mineralogical metamorphic indicators reviewed by Dodd (1969); (2) no correspondence with mineralogical-petrological metamorphic grade is evident; (3) Hg data for some chondrites correlate with shock facies (non-thermal) indicators (Dodd and Jarosewich, 1979); (4) small Hg activation energies (6-14 kcal/mole) require that the meteorites must have been stored in closed systems until low temperatures were attained. Hg must be presented as an involatile mineral(s) or as a substituent in a host phase at temperatures below 100 C. Consistent with this interpretation is the fact that despite diffusion times of 100-1,000,000 years at 200 K, Hg was retained in small objects over cosmic ray exposure periods of a hundred-million years.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geochimica et Cosmochimica Acta (ISSN 0016-7037); 49; 1743-175
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    Anatomy of a cosmic-ray neutrino source and the Cygnus X-3 system (1985)
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    Publication Date: 2011-08-19
    Description: The effects of an intense beam of ultra-high energy cosmic rays from a compact object in the Cygnus X-3 binary system hitting the companion star, and of the subsequent production of secondary neutrinos, are examined. A maximum allowable beam luminosity of about 10 to the 42nd erg/s is found for a system containing a 1-10 solar mass main sequence target star. The proton beam must heat a relatively small area of the target star to satisfy observational constraints on the resulting stellar wind. With such a model, the neutrino to gamma-ray flux ratio of about 1000 can result from a combination of gamma-ray absorption and a large neutrino to gamma-ray duty cycle ratio. It is found that the high density of the atmosphere resulting from compression by the beam leads to pion cascading and a neutrino spectrum peaking at 1-10 GeV energies.
    Keywords: ASTROPHYSICS
    Type: Nature (ISSN 0028-0836); 316; 418-420
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    The physical implications of an isothermal model for the hot intracluster medium (1985)
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    Publication Date: 2011-08-19
    Description: HEAO-1 A-2 and Einstein Observatory IPC observations of 15 clusters of galaxies have been used to measure the isothermal beta-model parameters, and the parameters are compared with those derived from model fits to the X-ray images. The physical constraints imposed on this model by existing optical data, the implied gas mass, and the gas contribution to the binding cluster mass are addressed. Values of beta less than unity are obtained, consistent with results from X-ray imaging data. This is interpreted to imply that the gas extends out to 8-10 core radii, about 2-3 Mpc. The isothermal gas mass can be as large as 60 percent of the virial mass for some clusters. This contradicts the fundamental assumption that the cluster potential is determined by an unseen mass which is given by the King approximation to an isothermal sphere, and it is concluded that the isothermal model is a nonphysical model.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 292; 441-446
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    High-energy X-ray observations of the Galactic center region (1985)
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    Publication Date: 2011-08-19
    Description: The region within five degrees of the Galactic center was observed in high-energy X-rays on November 12, 1977, and it is concluded that the emission definitely comes from more than one source. At least five 2-10 keV sources are important: the transient A1743 - 322, the binary GX 1 + 4, the bulge sources GX 3 + 1 and GX 5 - 1, and A1742 - 294. The composite spectrum of all the sources agrees with the continuum measured 12 days earlier by Leventhal, MacCallum, and Stang (1978) in the 70-250 keV range but, if extrapolated to higher energies, would be softer than and weaker than the HEAO 1 continuum observed in September 1977 or HEAO 3 continuum observed in the fall of 1979.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 290; 557-567
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    On fast X-ray rotators with long-term periodicities (1985)
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    Publication Date: 2011-08-19
    Description: The support of previous SAS 3 spacecraft observations by new data gathered by the Monitor Proportional Counter aboard the HEAO 2 spacecraft indicates that the pulse period history of the 13.5 sec-pulsing X-ray source LMC X-4 is consistent with standard accretion and torque models only if LMC X-4 is a fast rotator for which the accretion torques nearly cancel. This result leads to a neutron star magnetic field strength estimate of about 1.2 x 10 to the 13th G. Strong evidence is noted for Her X-1's status as a fast rotator, while SMC X-1 is probably an intermediate-to-fast rotator. In the context of slaved disk models for these objects, it is noted that the precession periods expected for the companion stars are significantly longer than the observed 1-2 month time scales; slaved disk models are thereby undermined.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 290; 487-495
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    Pole orientation of 16 Psyche by two independent methods (1985)
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    Publication Date: 2011-08-19
    Description: Nineteen new lightcurves of 16 Psyche are presented along with a pole orientation derived using two independent methods, namely, photometric astrometry and magnitude-amplitude-shape-aspect. The pole orientations found using these two methods agree to within 4 deg. The results from applying photometric astrometry were prograde rotation, a sidereal period of 0.1748143 days + or - 0.0000003 days, and a pole at longitude 223 deg and latitude +37 deg, with an uncertainty of 10 deg, and, from applying magnitude-amplitude-shape-aspect a pole at 220 + or - 1 deg, +40 + or - 4 deg, and a modeled triaxial ellipsoid shape (a greater than b greater than c) and a/b = 1.33 + or - 0.07. The discrepancy between the high-pole latitude found here and the low latitudes reported by Lupishko et al. (1982) and Zhou and Yang (1982) is discussed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 61; 241-251
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    Chemical zoning and homogenization of Pasamonte-type pyroxene and their bearing on thermal metamorphism of a howardite parent body (1985)
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    Publication Date: 2011-08-19
    Description: The Mg-Fe zoning of pyroxenes in Pasamonte and Juvinas eucrites is examined in order to gain a better understanding of the metamorphism in the surface layer of a eucrite/howardite parent body. Three distinct types of Ca-Mg-Fe zoning of Pasamonte pyroxenes are identified. The wide compositional range of the zoned pyroxenes suggests that Pasamonte is less metamorphosed than previously believed. It is also found that a Pasamonte-type pyroxene may yield a Juvinas-type pyroxene by thermal metamorphism. Calculations imply that the homogenization of Juvinas pyroxenes may have occurred during later reheating events rather than during initial cooling.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research, Supplement (ISSN 0148-0227); 90; C629-C63
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    Bibliography (1985)
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    Publication Date: 2011-08-19
    Description: Articles entered into the data base and Lunar and Planetary Institute Library in the period from May to October, 1983 are listed in annotated bibliography. The topics of the articles include asteroids, comets, and meteorites.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Earth, Moon, and Planets (ISSN 0167-9295); 32; 193-237
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    Electrosphere of an aligned magnetized neutron star (1985)
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    Publication Date: 2011-08-19
    Description: A fundamentally new self-consistent solution for the electrosphere of an aligned magnetized neutron star is presented. Unlike previous models the electrospheres are finite in extent. This avoids the light cylinder problem. The results may provide a basis for pulsar models.
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society, Monthly Notices (ISSN 0035-8711); 213; 43P-49P
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    Conjecture about a hurricane system in the Jovian atmosphere (1985)
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    Publication Date: 2011-08-19
    Description: Arguments are presented in support of the hypothesis that the Great Red Spot (GRS) of Jupiter is a giant hurricane, and that the same decription might apply to the smaller vortices such as the white and brown ovals (barges) on the surface of Jupiter. Estimates of the spin-down times constants for the white and brown oval vortices, indicate that the motions must be sustained by the continued release of internal energy. In analogy with the CISK mechanism for terrestrial hurricanes, transport of water vapor is identified as a possible latent energy source. On the basis of the large size and long life time of the GRS, (indicating extreme depth), it is suggested that the hurricane GRS hurricane may have been induced by meteor impact. Voyager 1 images of the GRS are provided.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Earth, Moon, and Planets (ISSN 0167-9295); 32; 183-192
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    MgS grain component in circumstellar shells (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: In this letter, far-infrared spectrophotometry (30-55 microns) and photometry (53-200 microns) are presented which define, for the first time, the long wavelength limit of the previously unidentified 30 micron emission feature found in certain extreme carbon star spectra. The spectral similarities are sufficiently similar to those of solid MgS that MgS is proposed to be the band carrier. This is interpreted as the first direct evidence that chemical surface reactions occur on dust grains in circumstellar environments. The presence of MgS indicates that either the oxygen abundance is relatively low and/or the sulfur abundance is high in extreme carbon stars.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 290; L35-L39
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  • 60
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    Laboratory infrared spectra of predicted condensates in carbon-rich stars (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Laboratory spectra and mass absorption coefficients of MgS, CaS, FeS, SiS2, FeS2, Fe3C, and a commercial iron carbide are presented over the wavelength range 125-15 microns. These spectra confirm that MgS is the most likely source of the unidentified 30-micron emission in carbon-rich sources and that FeS, Fe3C, and 'iron carbide' cannot be responsible for this feature although they could contribute to the continuum in this region. CaS and FeS2 may contribute to the 30-micron feature; however, both higher resolution and higher precision astronomical observations are needed before their presence can be established. SiS2 has a peak near 22 microns and therefore cannot be a significant component of the dust in such regions.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 290; L41-L43
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  • 61
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    Polycyclic aromatic hydrocarbons and the unidentified infrared emission bands - Auto exhaust along the Milky Way (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The unidentified infrared emission features (UIR bands) are attributed to a collection of partially hydrogenated, positively charged polycyclic aromatic hydrocarbons (PAHs). This assignment is based on a spectroscopic analysis of the UIR bands. Comparison of the observed interstellar 6.2 and 7.7-micron bands with the laboratory measured Raman spectrum of a collection of carbon-based particulates (auto exhaust) shows a very good agreement, supporting this identification. The infrared emission is due to relaxation from highly vibrationally and electronically excited states. The excitation is probably caused by UV photon absorption. The infrared fluorescence of one particular, highly vibrationally excited PAH (chrysene) is modeled. In this analysis the species is treated as a molecule rather than bulk material and the non-thermodynamic equilibrium nature of the emission is fully taken into account. From a comparison of the observed ratio of the 3.3 to 11.3-micron UIR bands with the model calculations, the average number of carbon atoms per molecule is estimated to be about 20. The abundance of interstellar PAHs is calculated to be about 2 x 10 to the -7th with respect to hydrogen.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 290; L25-L28
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  • 62
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    The R Aquarii system at optical and radio wavelengths (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: New continuum observations of all radio components of the R Aquarii system at 2, 6, and 20 cm are reported which allow determination of polarization properties, integrated flux levels, spectral indices, and hence the emission mechanisms of the individual components. Complementary wide-band optical observations are also reported to help determine the nature and structure of the compact double radio source (CDRS) and the R Aquarii radio jet. The results of these observations are discussed in detail with regard to models currently or previously proposed for the R Aquarii system. It is concluded that the compact H II region spectral index is about +0.6, indicative of a thermal and optically thick expanding wind from the long-period variable. The radio jet emission is shown to be optically thin, thermal, cospatial with optical emission, and stable over the last few years. The CDRS is shown to be an extragalactic background object.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 289; 765-767
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  • 63
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    Gravity field of the Jovian system from Pioneer and Voyager tracking data (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Data sets from the Voyager and Pioneer flybys of Jupiter and the Galilean satellites are employed to characterize the Jovian magnetic field and the effects of the Io torus on transmissions. Both optical and Doppler radio data are considered, except for periods when the Jovian radiation environment disturbed the oscillator stability of the radio transmitters. Account is taken of small accelerations of the spacecraft by tidal forces of a single rising satellite, density differences in the Great Red Spot producing a columnar gravitational change, and three unknown objects in the inner Jovian system. Correction parameters are developed for the effects on the S-band data induced by the Jovian plasmasphere inwards from the Io torus. Calculations are then made of the planet and satellite masses, gravity harmonic coefficients, and orientation of the rotational pole. Large reductions in the uncertainties in previous mass estimates are obtained.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Astronomical Journal (ISSN 0004-6256); 90; 364-372
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  • 64
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    Large arcuate scars: A geological legacy of the Earth's accretionary past (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Immediately following accretion, the surface of the Earth was densely patterned with circular scars which were the surface expressions of 3-D craterform structures. In the course of geological time these structures would have become less and less visible due to the workings of the Earth's atmosphere, surface waters, and plate tectonics regime but there is no compelling reason to assume that they have been entirely eradicated. Furthermore, a very imperfect analogy with the other inner planets suggests that geological processes may not in fact be capable of totally erasing such deep features. Some illustrative examples of arcuate scars are discussed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Lunar and Planetary Inst. Workshop on the Early Earth: The Interval from Accretion to the Older Archean; p 71-73
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  • 65
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    Lunar and Martian impact basins: Exposed records of terrestrial bombardment? (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The unrecycled surfaces of the Moon, Mercury, and Mars preserve the very early history of impact bombardment and its effect on crustal evolution. Previous studies indicated that the post accretion impact flux by large bodies on Mars may have been dificient, but systematic studies recently have revealed that this deficiency is largely the result of active erosional and depositional processes during the first 0.8 by. Ancient Martian impact basins larger than 300 km in diameter are revealed by subtle but unequivocal topographic and structural control of drainage patterns. In addition, the largest basins have left a deep seated imprint of concentric and radial structural patterns that control the occurrence of most Martian volcanic and tectonic provinces. If 10(-6)/km(2) is considered to be a reasonable approximation for the density of impact basins ( 300 km) of the Moon and Mars, then the Earth should have recorded more than 500 impacts that resulted in basins larger than 300 km in diameter over its post accretion geologic history. If calibrated with the Moon, then most of these impacts occurred prior to 3.8 by.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Workshop on the Early Earth: The Interval from Accretion to the Older Archean; p 74-75
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  • 66
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    Water loss from Venus: Implications for the Earth's early atmosphere (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The atmosphere of Venus outgassed rapidly as a result of planetary heating during accretion, resulting in massive water loss. The processes affecting atmospheric chemistry following accretion have consisted largely of hydrogen escape and internal re-equilibrium. The initial bulk composition of Venus and Earth are assumed to have been roughly similar. Chemical speciation on Venus was controlled by the temperature and oxygen buffering capacity of the surface magma. It is also assumed that the surfaces of planetary bodies of the inner solar system were partly or wholly molten during accretion with a temperature estimated at 1273 to 1573 K. To investigate the range of reasonable initial atmospheric compositions on Venus, limits have to be set for the proportion of total hydrogen and the buffered fugacity of oxygen. Using the C/H ratio of 0.033 set for Earth, virtually all of the water generated during outgassing must later have been lost in order to bring the current CO2/H2O ratio for Venus up to its observed value of 10 sup 4 to 10 sup 5. The proportion of H2O decreases in model atmospheres with successfully higher C/H values, ultimately approaching the depleted values currently observed on Venus. Increasing C/H also results in a rapid increase in CO/H2O and provides an efficient mechanism for water loss by the reaction CO+H2O = CO2 + H2. This reaction, plus water loss mechanisms involving crustal iron, could have removed a very large volume of water from the Venusian atmosphere, even at a low C/H value.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Lunar and Planetary Inst. Workshop on the Early Earth: The Interval from Accretion to the Older Archean; p 65-67
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  • 67
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    The origin of continental crust: Outlines of a general theory (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The lower continental crust, formerly very poorly understood, has recently been investigated by various geological and geophysical techniques that are beginning to yield a generally agreed on though still vague model (Lowman, 1984). As typified by at least some exposed high grade terranes, such as the Scottish Scourian complex, the lower crust in areas not affected by Phanerozoic orogeny or crustal extension appears to consist of gently dipping granulite gneisses of intermediate bulk composition, formed from partly or largely supracrustal precursors. This model, to the degree that it is correct, has important implications for early crustal genesis and the origin of continental crust in general. Most important, it implies that except for areas of major overthrusting (which may of course be considerable) normal superposition relations prevail, and that since even the oldest exposed rocks are underlain by tens of kilometers of sial, true primordial crust may still survive in the lower crustal levels (of. Phinney, 1981).
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Lunar and Planetary Inst. Workshop on the Early Earth: The Interval from Accretion to the Older Archean; p 54-56
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  • 68
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    Implications for the Earth of the early dynamical environment (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The formation of the Earth, was mainly from sizeable bodies: perhaps moon sized. Models of interaction among small planetesimals which take into account only close encounters all lead to the formation of moon sized objects, thus leading to several 100 in the inner solar system. Longer term interactions, such as secular resonance sweepings, are needed to get these planetesimals together to form the observed terrestrial bodies. After the accumulation of the Earth, during which core formation certainly occurred, further impacts probably influenced the locations of rifting centers in the system of mantle convection and crustal differentiation. They may have affected craton stabilization by promoting lateral heterogeneity, but had little influence on the key problem of early recycling of sial.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Lunar and Planetary Inst. Workshop on the Early Earth: The Interval from Accretion to the Older Archean; p 45-47
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  • 69
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    A review of tectonic aspects of the Limpopo belt and other Archean high-grade gneissic terranes (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Published information on the Archean high grade terrains varies a great deal in the detail available. Such information as exists indicates marked differences in the lithic types and proportions present in the central Limpopo belt compared with the better studies of the other Archean high grade terrains. These differences may be important because they are expressed by the presence in the Limpopo belt of subordinate, but significant quantities (about 5% each) of two rock suites likely to have formed on a shallow marine platform of significant size (Eriksson and Kidd, in prep.). These suites consist of thick sections dominantly consisting of either carbonate and calc-silicate, or of pure metaquartzites, often fuchsite bearing, whose lithic characters are unlike those expected for metacherts but are very like those expected for platform arenites. Isotopic ages suggest these sediments are probably older than 3.3 Ga and younger than 3.5 Ga. Studies lead to the conclusions that (1) continental fragments large enough to provide a substrate for significant platform arenite and carbonate sedimentation existed by 3.3 to 3.5 Ga ago; (2) Wilson cycle tectonics seems to adequately explain most major features of the Archean gneissic terranes; and (3) Tibetan-Himalayan style collisional tectonics 2.6 Ga and older accounts for the large scale relationships between the Limpopo belt and the adjacent Archean greenstone granitoid terrane cratons. By inference, other more fragmentary Archean gneissic terranes may have once been part of such collisional zones.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Lunar and Planetary Inst. Workshop on the Early Earth: The Interval from Accretion to the Older Archean; p 48-49
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  • 70
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    Anorthositic oceanic crust in the Archean Earth (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Ultrapure minerals separated from eclogite inclusions in kimberlites were analyzed for Sm, Nd, Sr, and oxygen isotopes and for major and trace elements. Clinopyroxene (cpx) and garnet (gnt) are the only primary mineral phases in these rocks, and mineral phases and their alteration products. The WR sub calc. is the reconstructed bulk composition excluding all the contamination influences. Two groups of eclogites: are distinguished: (1) type A Noritic-anorthositic eclogites; and (2) type B Ti-ferrogabbroic eclogites. The oxygen isotopes are primary mantle-derived features of these rocks and are not caused by posteruption processes, as they were measured on unaltered, clean mineral separates and show a correlation with REE pattern and Sr and Nd isotopes. It is suggested that the variation of the oxygen isotopes are caused by crustal-level fluid-rock interaction at relatively low temperature. It is shown that oxygen isotopes variation in MORB basalts caused by the hydrothermal system are in the same range as the observed oxygen isotope variation in eclogites. A model to explain the new set of data is proposed. It is thought that some of these eclogites might be emplaced into the upper lithosphere or lower crust at the time corresponding to their internal isochron age. The calculated WR composition was used to estimate model ages for these rocks.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Lunar and Planetary Inst. Workshop on the Early Earth: The Interval from Accretion to the Older Archean; p 40-41
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  • 71
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    Noble gases and the early history of the Earth: Inappropriate paradigms and assumptions inhibit research and communication (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The development of models as tracers of nobel gases through the Earth's evolution is discussed. A new set of paradigms embodying present knowledge was developed. Several important areas for future research are: (1) measurement of the elemental and isotopic compositions of the five noble gases in a large number of terrestrial materials, thus better defining the composition and distribution of terrestrial noble gases; (2) determinations of relative diffusive behavior, chemical behavior, and the distribution between solid and melt of noble gases under mantle conditions are urgently needed; (3) disequilibrium behavior in the nebula needs investigation, and the behavior of plasmas and possible cryotrapping on cold nebular solids are considered.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Lunar and Planetary Inst. Workshop on the Early Earth: The Interval from Accretion to the Older Archean; p 37-38
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  • 72
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    Constraints on the development of the early continental crust from isotopic data (1985)
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    Publication Date: 2011-08-19
    Description: Aspects of the origin and development of the early (AE) continential crust are addressed by radiogenic isotope and trace element studies. The most important ones are: (1) at what time did the earliest continental crust form; (2) what was its composition; (3) by what processes did it grow and by what processes was it destroyed; (4) what were the rates of production and destruction as a function of time during this time period? Nd is isotopic data on the oldest terrestrial rocks indicate that the mantle at this time had already suffered substantial depletion in incompatible elements due to earlier continent forming events. Isotopic data on young volcanic rocks derived from the depleted mantle show no evidence of this early history. The observed isotopic patterns of Nd, Sr, Hf and Pb through time together with the presently observed age spectrum of crustal rocks are considered. These patterns can be modelled by a transport model in which the continental growth and destruction rates are allowed to vary as a function of time. It is suggest that the mass of the continents at 3.8 AE ago was about 25% of the current continental mass. However, due to the very high recycling rates obtained in the early Archean only a few percent of this crust has been preserved up to the present.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Lunar and Planetary Inst. Workshop on the Early Earth: The Interval from Accretion to the Older Archean; p 39
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  • 73
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    Submarine hydrothermal environments as sites for the origin and evolution of life (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: That life formed and evolved in hydrothermal environments is proposed. This hypothesis is plausible in terms of the tectonic, paleontological, and degassing history of the Earth. Submarine hydrothermal vents are the only contemporary geological environment which may truly be called primeval and which today continue to be a major source of gases and dissolved elements to the ocean. The microbial assemblages in present day hydrothermal systems therefore could be living analogues of the earliest microbial communities to develop on Earth. The evidence for the hypothesis is reviewed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Lunar and Planetary Inst. Workshop on the Early Earth: The Interval from Accretion to the Older Archean; p 34-36
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  • 74
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    The degassing history of the Earth: Noble gas studies of Archaean cherts and zero age glassy submarine basalts (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Recent noble gas studies suggests the Earth's atmosphere outgassed from the Earth's upper mantle synchronous with sea floor spreading, ocean ridge hydrothermal activity and the formation of continents by partial melting in subduction zones. The evidence for formation of the atmosphere by outgassing of the mantle is the presence of radionuclides H3.-4, Ar-040 and 136 Xe-136 in the atmosphere that were produced from K-40, U and Th in the mantle. How these radionuclides were formed is reviewed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Lunar and Planetary Inst. Workshop on the Early Earth: The Interval from Accretion to the Older Archean; p 28-30
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  • 75
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    The 3.5 b.y. old Onverwacht Group: A remnant of ancient oceanic crust (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The interaction between seawater and submarine volcanic rock has had important consequences for the chemistry of the ocean during the Phanerozoic. Most extant terranes have been regionally metamorphosed to the amphibolite and granulite facies, so that their precursor lithologies and structures are not readily determinable. However, the 3.5 b.y. old supracrustal rocks of the Barberton Mountain Land, South Africa, have not been subjected to high grade regional metamorphism, and therefore there was reason to hope that a laboratory investigation might reveal the extent to which these rocks had been exposed to subseafloor hydrothermal activity. Hart and de Wit describe bulk geochemical evidence from the entire suite as well as field evidence which support the concept of hydrothermal activity in the Barberton Mountain Land. Mineralogical and textural features which unequivocally mark it as a submarine sequence emplaced in a midocean ridge/fracture zone or back arc/fracture zone environment are briefly discussed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Lunar and Planetary Inst. Workshop on the Early Earth: The Interval from Accretion to the Older Archean; p 31-33
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  • 76
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    Considerations of large scale impact and the early Earth (1985)
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    Publication Date: 2011-08-19
    Description: Bodies which have preserved portions of their earliest crust indicate that large scale impact cratering was an important process in early surface and upper crustal evolution. Large impact basins form the basic topographic, tectonic, and stratigraphic framework of the Moon and impact was responsible for the characteristics of the second order gravity field and upper crustal seismic properties. The Earth's crustal evolution during the first 800 my of its history is conjectural. The lack of a very early crust may indicate that thermal and mechanical instabilities resulting from intense mantle convection and/or bombardment inhibited crustal preservation. Whatever the case, the potential effects of large scale impact have to be considered in models of early Earth evolution. Preliminary models of the evolution of a large terrestrial impact basin was derived and discussed in detail.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Lunar and Planetary Inst. Workshop on the Early Earth: The Interval from Accretion to the Older Archean; p 23-24
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  • 77
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    The problem of the Earth's CO2 content and the iron core (1985)
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    Publication Date: 2011-08-19
    Description: The near absence of metallic iron and the presence of magnetite and FeS in the C-1 chondrites imply that metallic iron was a minor phase present during the accretion process that formed the C-1 chondrites. If the C-1 chondrites provided the bulk of the initial planetary growth materials, the carbon reduction model is favored. The above estimates suggest that some 1240 to 227 times as much CO2 may have been produced during the formation of the core than can be accounted for in the crust and mantle. This discrepancy taken to the extreme suggests either that: (1) the Earth has lost more than 99 percent of its initial CO2 during early differentiation (this is highly unlikely) or: (2) the Earth has acquired some 90 percent of its present mass by the accretion of debris from previously reduced and differentiated but subsequently disrupted planetary bodies whereby the associated CO2 would not be captured, or: (3) the C-1 chondrites represent only a trivial fraction of the initial accretion materials present in the nebular cloud or: (4) condensed iron and anhydrous silicate phases were preferentially accreted during the initial formation of the planetary bodies.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Lunar and Planetary Inst. Workshop on the Early Earth: The Interval from Accretion to the Older Archean; p 20-22
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  • 78
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    High-angular resolution observations of stellar binary systems (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A long-term program designed to investigate the spatial structure of centimetric radio emission from close binary systems using multistation VLBI array is discussed. Eleven binaries, including eight RS CVn systems, Algol, LSI 61 deg 303, and Cyg X-1, have been detected. The measured brightness temperatures vary from T(B) about 10 exp 8.5 K during periods of low activity to T(B) about 10 exp 10.5 K during flares. Extensive observation of a few sources has shown that the spatial structure is 'core-halo' with linear dimensions of about a stellar radius and the binary system, respectively. The observations are consistent with gyrosynchrotron emission of mildly relativistic electrons in magnetic fields of about 10 exp 1.5 + or - 0.5 gauss. The core sources appear to be optically thick, while the halo component is optically thin.
    Keywords: ASTROPHYSICS
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  • 79
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    The dynamical history of comet Halley (1985)
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    Publication Date: 2011-08-19
    Description: The history of the attempts to predict the motion of comet Halley is outlined and the importance of the so-called nongravitational forces acting upon this comet is emphasized. Recent orbital work of the International Halley Watch Astrometry Network is reviewed. Comet Halley's transverse nongravitational parameter is positive and nearly constant with time suggesting that the comet is in direct rotation without precession of the spin pole. The nongravitational effects are consistent with the vaporization of water ice from the comet's nucleus and long term integrations suggest that the comet has been in its present orbit for at least 16,000 years and probably much longer.
    Keywords: ASTROPHYSICS
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  • 80
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    Morphological and physical characteristics of the Virgo Cluster - First results from the Las Campanas photographic survey (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Preliminary results are presented of a photographic survey of the Virgo cluster to the faintest convenient limit of the Las Campanas du Pont 2.5 m reflector, performed in order to study the complexity of both the surface and velocity distributions within the central 6 degree radius region. The survey is described and the resulting Catalog is discussed, and the frequency of galaxy types found and listed in the Catalog is described. The physical properties of the dwarfs are summarized, and luminosity functions are given separately for each morphological type. The progressive change of (MBT) faintward along the morphological sequence from Sc I through Sm and Im types is shown, leading to a calibration of the de Vaucouleurs Lambda luminosity index and a determination of its intrinsic dispersion. The preliminary results on the distribution of galaxies of all types in the two principal subclustering regions found are summarized, and the velocity distributions over the face of the 6 degree core are discussed for the various galaxy types.
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  • 81
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    Bipolar nebulae and mass loss from red giant stars (1985)
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    Publication Date: 2011-08-19
    Description: Observations of several bipolar nebulae are used to learn something of the nature of mass loss from the probable red-giant progenitors of these nebulae. Phenomena discussed are: (1) probable GL 2688's optical molecular emissions; (2) newly discovered very high velocity knots along the axis of OH 0739 - 14, which reveal evidence for mass ejections of + or 300 km/s from the M9 III star embedded in this nebula; (3) the bipolar structure of three extreme carbon stars, and the evidence for periodic mass ejection in IRC + 30219, also at high speed (about 80 km/s); and (4) the curious cool TiO-rich region above Parsamian 13, which may represent the very recent shedding of photospheric material from a cool, oxygen-rich giant. Several general key questions about bipolar nebulae that relate to the process of mass loss from their progenitor stars are raised.
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  • 82
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    Infrared studies of the bipolar nebula OHO739 (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Infrared studies have been made of the M9 giant OHO739, which is embedded in a bipolar nebula, in order to study the structure and density distribution of the circumstellar disk, and preliminary results are reported. The degree of polarization across the 3.1 micron ice band in an 8 arcsec beam centered at the 2.2 micron peak is found to increase with extinction in the ice band, as expected for a bipolar scattering nebula. A distance of 2 kpc is inferred from the tilt angle of the bipolar axis and phase lag measurements of the OH maser. Maps made in the K band and in narrow bands at 2.85, 3.1, and 3.5 microns by raster-scanning OHO739 are presented. In all maps, the object is clearly elongated along the bipolar axis. Patterns of increases and decreases in extinction in the object are inferred to indicate that ice particles are widespread through the nebula and not just concentrated in the disk.
    Keywords: ASTROPHYSICS
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  • 83
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    Hydrogen deficiency and mass loss from AGB stars (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Theoretical studies predict that mass loss from stars should accelerate once stars on the AGB begin thermal pulsations (TP). It has been discovered that the stars on this part of the AGB are apparently hydrogen deficient. This development may be related to the mass loss predicted by theory. Hydrogen deficiency is also supported by the nondetection of H2 in non-Mira stars, S stars, and carbon stars. The possibility that the observed apparent hydrogen deficiency has resulted from a mass loss process is considered. Observations indicate that TP-AGB stars become hydrogen deficient before the Mira phase.
    Keywords: ASTROPHYSICS
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  • 84
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    The problem of water on Mars (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: LUNAR AND PLANETARY EXPLORATION
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  • 85
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    Electrolytic currents in Europa (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The transverse electric (TE) and transverse magnetic (TM) currents at the Europan surface are calculated. The study was performed because of the proximity of Europa to Jupiter, which has a strong magnetic field, and the presence of a conductor (water ice) in copious quantities on the Europan surface. The moon is assumed to have a silica interior, an ice layer and, in places, an intermediate liquid layer. Account is taken of surface eddy currents, the maximum current density in the surface and a saline liquid layer, and the TM magnitudes with different liquid layer thicknesses. The effects of random appearances of vertical cracks in the ice are also considered. The calculations indicate that the surface currents could be higher on Europa than on Io, but may be too weak to produce heating effects sufficient to prevent refreezing of a crack.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 63; 39-44
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  • 86
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    On the proposed triggering of Jovian radio emissions (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Calvert (1985) has proposed that a solar type III radio bursts can trigger the onset of certain Jovian hectometer wavelength emissions. It is shown, using the data obtained by the Voyager Planetary Radio Astronomy experiment, that this triggering hypothesis is not supported statistically. Furthermore, the causality of this proposed triggering is questioned because much of the Jovian hectometer emission is due to a quasi-continuous radio source rotating, in lighthouse fashion, with Jupiter. Thus, an observed 'onset' of emission is simply a function of the observer's position in local time around Jupiter.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Geophysical Research Letters (ISSN 0094-8276); 12; 621-624
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  • 87
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    Lunar sample 14425 - Corrected analysis (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A polished section of lunar sample 14425, an 8 mm glass bead, was studied using a scanning electron microscope and energy-dispersive X-ray analyzer. The silicon, aluminum, iron, magnesium, calcium, sodium, potassium, titanium, and chromium contents of the glass were determined. Two types of glass are visible in the polished section. One is clear and almost devoid of metallic spherules, while the other is cloudy and contains numerous metallic spherules, some less than one micron in size. Both glass types are homogeneous and identical in composition. This composition closely matches that of some Apollo 14 breccias or glass found in the breccias. The apparent similarity in composition between lunar sample 14425 and the high-magnesium microtektites found in a previous study was probably due to charging effects during analyses in which the sample was uncoated.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Science (ISSN 0036-8075); 220; 1410
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  • 88
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    Spectral constraints on models of gas in clusters of galaxies (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The HEAO 1A2 spectra of clusters of galaxies are used to determine the temperature profile which characterizes the X-ray emitting gas. Strong evidence of nonisothermality is found for the Coma, A85, and A1795 clusters. Properties of the cluster potential which binds the gas are calculated for a range of model parameters. The typical binding mass, if the gas is adiabatic, is 2-4E14 solar masses and is quite centrally concentrated. In addition, the Fe abundance in Coma is .26 + or - .06 solar, less than the typical value (.5) found for rich clusters. The results for the gas in Coma may imply a physical description of the cluster which is quite different from what was previously believed.
    Keywords: ASTROPHYSICS
    Type: Space Science Reviews (ISSN 0038-6308); 40; 681-688
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  • 89
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    H0323+022 - Classification as a BL Lac and EXOSAT coordinated observations (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The object H0323+022 (Doxsey et al. 1983) has been shown to be a BL Lac object by virtue of a diversity of observational characteristics at radio, optical, and X-ray wavelengths, in agreement with the conclusion of Margon and Jacoby (1984). Multi-frequency coordinated observations of this highly variable object with EXOSAT in September 1984 found it to be in a faint quiescent state (approximately 1/3 micron-Jy at approximately 5 keV and V = 16.55). Preliminary results from the latter observations are presented.
    Keywords: ASTROPHYSICS
    Type: Space Science Reviews (ISSN 0038-6308); 40; 613-617
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  • 90
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    The discovery of a 25 min regular modulation in the X-ray flux from 2S0142 + 61 (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A 13 hr observation of 2S0142 + 61 on August 27, 1984 by EXOSAT shows the X-ray flux of 2S0142 + 61 to be modulated with a period of 1456+/-6 s. The 1-10 keV spectrum is two component with an approximately 0.7 keV thermal and 0.0 energy index power law, with 30 percent of the total luminosity in the thermal component. The spectrum is absorbed by about 1 x 10 to the 22nd H per sq cm. Only the hard component is pulsed with a 3 to 10 keV peak to mean amplitude of 35 percent. Below 2 keV the modulation is less than a few percent. The total 1-10 keV luminosity is 3.5 x 10 to the 32nd erg/s for a distance of 100 pc. Possible optical counterparts are discussed.
    Keywords: ASTROPHYSICS
    Type: Space Science Reviews (ISSN 0038-6308); 40; 157-162
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  • 91
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    Magnetic field properties of Jupiter's tail at distances from 80 to 7500 Jovian radii (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The results of a detailed study of the magnetic field data on the near and distant Jovian magnetotail from both Voyager 1 and 2 are presented. The spacecraft trajectories and the data are reviewed, and four distant tail encounters are examined and compared with the corresponding Voyager 1 interplanetary data sets. A power spectral analysis of both the near and distant tail intervals is given, and some of the differences between the tail encounters and the power spectra of these control data sets are discussed. Two solar wind or magnetosheath data sets obtained when Voyager 2 was not in the distant tail are analyzed. These more 'normal' solar wind conditions are contrasted with those reflected in both the Voyager 2 distant tail encounters and the conditions monitored by Voyager 1 farther downstream.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 8223-823
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  • 92
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    Modeling the effects of latitudinal gradients in stellar winds, with application to the solar wind (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: A steady, axisymmetric, quasi-radial, global model previously developed for stellar winds with embedded magnetic fields has been extended to include latitudinal gradient effects on the azimuthal velocity and magnetic field. The linear results at large radii are presented for large-amplitude latitudinal variations in the radial magnetic field, mass loss rate, and radial velocity of the wind. The magnetohydrodynamic (MHD) equations predict meridional flows that develop naturally from internal magnetic stresses. The flows open flux tubes in the star's equatorial plane, redistributing mass and magnetic flux as a function of stellar latitude. The plasma spins up to conserve angular momentum in fields and plasma. The results are generally applicable to stellar winds (including radiatively driven winds), provided that the internal structure is not dominated by rotation. The asymptotic solutions do not explicitly depend on the form of the energy equation, although the assumed O(1) state which drives these solutions depends on the deposition of energy and momentum throughout the wind.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 296; 259-267
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  • 93
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    An interpretation of the spectral variations of Theta Coronae Borealis (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Measurements are presented of the strengths and displacements of sharp absorption components of the resonance lines of Si IV, C IV, and Al III in the spectrum of Theta CrB. No evidence is found for mass loss at a detectable rate. A qualitative model of a Be star is developed. It is suggested that the spectral variations of Theta CrB are the result of changes in the rate at which magnetic flux is generated in the envelope of the star and extruded through the photosphere of the star.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 148; 2, Ju
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  • 94
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    Black hole accretion disks - Electrodynamic coupling of accretion-disk coronae and the partitioning of soft and hard X-ray emission (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: It is demonstrated that the observed large ratio of hard to soft X-ray emission and the bimodel behavior of black hole accreting X-ray sources such as Cygnus X-1 can be described in terms of a magnetically structured accretion disk corona which is electrodynamically coupled to the disk turbulent motions while the disk is thermodynamically coupled to the corona as described by a feedback parameter delta. The observed ratio of hard to soft X-ray emission is independent of the disk thickness, and weakly dependent of the disk parameter alpha relating the disk viscous stresses to the total pressure. Observed values of the luminosity ratio point towards strong differences of the feedback of the low state compared to the high state, in the sense that low state means small feedback (delta less than 0.2) and high state means strong feedback delta of about 0.5.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 148; 2, Ju; 309-311
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  • 95
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    Light variations of Periodic Comet Halley beyond 7 AU (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The present examination of brightness data on the Periodic Comet Halley over the October 1982-February 1984 period, for evidence concerning nucleus rotation period and projected cross section area, notes variations of up to 5:1 in intrinsic brightness. Application of a period-determination technique has failed to yield a clear choice for the true rotation period among a large number of peaks in the spectrum, some of which virtually coincide with the sun's rotation period and its submultiples. It is found that rotation periods longer than about 1 day are the most likely; it is suggested that the observed light curve is a composition of periodic and erratic variations.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 148; 2, Ju; 299-308
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  • 96
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    Soft X-ray spectral observations of low-luminosity active galaxies (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The X-ray spectra of a sample of 12 low-luminosity AGNs observed using the solid state spectrometer on the HEAO 2 satellite are investigated. The AGNs discussed here have X-ray luminosities below about 10 to the 44th erg/s, and thus form a sample complementary to the higher luminosity sample discussed by Petre et al. (1984). The spectra are well described by a simple model consisting of a power law, with photon spectral index about 1.7, plus absorption by cold gas. The objects in the sample can be separated into three groups: (1) those whose spectra show no significant absorption; (2) those for which the X-ray source is totally covered by a spatially uniform absorbing medium; and (3) those for which partial covering by 'patchy' absorbers is indicated. Column densities and covered fractions do not correlate systematically with X-ray luminosity. Implications regarding physical conditions in AGNs are discussed.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 296; 69-89
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  • 97
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    Bending waves and the structure of Saturn's rings (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The surface mass density profiles at four locations within Saturn's rings are calculated using Voyager spacecraft images of spiral bending waves. The identification of a feature in Saturn's outer B ring as Mimas's 4:2 bending waves is confirmed, and these 4:2 waves are analyzed to determine the surface density in Saturn's B ring. A fourth set of bending waves, the Mimas 7:4, located in the inner A ring, is identified and analyzed. Mimas's 5:3 and 8:5 bending waves, observed in the middle and outer A ring respectively, are reanalyzed.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 62; 433-447
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  • 98
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    Bolometric albedos of Titan, Uranus, and Neptune (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The energy budgets of Titan, Uranus, and Neptune are reevaluated using new observational data on energy input as well as unpublished data on energy output. The bolometric geometric albedo of each object was determined, and preliminary determinations of the phase functions were used to compute the Bond albedos and effective temperatures. The values for the latter are 83 + or - 2 K for Titan, 57 + or - 2 K for Uranus, and 47 + or - 2 K for Neptune. The effective temperature of Titan is greater than the observed brightness temperatures in the thermal infrared region of the spectrum, indicating that the emissivity is less than unity for this part of the spectrum. An internal luminosity of (3.9 + or 1.1) x 10 to the 15th W is found for Neptune, and an upper limit of (0.6 + or - 1.4) x 10 to the 15th W is found for Uranus.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Icarus (ISSN 0019-1035); 62; 425-432
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  • 99
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    VLBI observations of the jet in Cygnus A (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The luminous radio galaxy Cyg A was observed with a five-station US VLBI array at 5 GHz at epoch 1983.25. The jet can be followed from the core to a distance of 9 milliarcsec (mas). Within the limited dynamic range of these observations, it is one-sided (jet:counterjet ratio greater than 12:1). If this one-sidedness is due to Doppler boosting, then (1) the jet must decelerate to a mildly relativistic velocity on a kiloparsec scale, (2) the source cannot lie with 30 deg of the plane of the sky. The jet points directly at the base of the kpc-scale jet seen by Perley, Dreher, and Cowan (1984); the curvature occurs primarily or entirely on a scale of 10-100 kpc. The jet brightness falls off more slowly inside 1 kpc than in other powerful sources. A search for compact structure in the three bright hot spots revealed no structure lower than 3 mas in size with flux greater than 6 mJy.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 295; 463-465
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  • 100
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    Radial diffusion in magnetodiscs (1985)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: The orbits of charged particles in magnetodiscs are considered. The bounce motion is assumed adiabatic except for transits of a small equatorial region of weak magnetic field strength and high field curvature. Previous theory and modeling have shown that particles scatter randomly in pitch angle with each passage through the equator. A peaked distribution thus diffuses in pitch angle on the time scale of many bounces. It is argued in this paper that spatial diffusion is a further consequence when the magnetodisc has a longitudinal asymmetry. A general expression for DLL, the diffusion of equatorial crossing radii, is derived. DLL is evaluated explicitly for ions in Jupiter's 20-35 radii magnetodisc, assumed to be represented by Connerney et al.'s (1982) Voyager model plus a small image dipole asymmetry. Rates are energy, species, and space dependent but can average as much as a few tenths of a planetary radius per bounce period.
    Keywords: LUNAR AND PLANETARY EXPLORATION
    Type: Journal of Geophysical Research (ISSN 0148-0227); 90; 7587-759
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