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  • 1
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    Space debris impact experiment (S0001) (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: The specific objectives of this experiment are to establish the population and size distribution of meteoroids in the mass range from 10 to the minus 10 power to 10 to the minus 4 power G, to establish the current population of man-made debris in the same mass range, and to obtain data on the physical properties (composition and density) of meteoroids.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Long Duration Exposure Facility (LDEF); p 136-137
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  • 2
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    Space environment effects (M0006) (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: The effects of long term exposure to the near Earth space environment on advanced electrooptical and radiation sensor components were examined. The effect of long duration spaceflight on the germination rate of selected terrestrial plant seeds is observed in exobiological experiments.
    Schlagwort(e): ASTRONAUTICS (GENERAL)
    Materialart: NASA. Langley Research Center Long Duration Exposure Facility (LDEF); p 185-187
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  • 3
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    Interplanetary dust experiment (A0201) (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: The objective of this experiment is to study interplanetary dust, variously referred to as cosmic dust, cometary dust, zodiacial dust, or meteoric dust particles. Specific objectives are to obtain information regarding particle mass and velocity, and to undertake correlative analyses with other experiments, both on LDEF or near the time of the LDEF flight.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Long Duration Exposure Facility (LDEF); p 134-135
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  • 4
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    Attempt at dust debris collection with stacked detectors (A0138-2) (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: The primary objective of this experiment is to investigate the feasibility of future missions of multilayer thin-film detectors acting as energy sorter to collect micrometeoroids, if not in their original shape, at least as fragments suitable for chemical analysis. It is expected that this kind of particle collector will help in solving one of the most puzzling topics in cosmic-dust studies: the mineralogical and chemical composition of the particles. This is a matter of great interest in the study of the origin and evolution of the solar system.
    Schlagwort(e): ASTROPHYSICS
    Materialart: NASA. Langley Research Center Long Duration Exposure Facility (LDEF); p 124-126
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  • 5
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    Interstellar-gas experiment (A0038) (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: The objectives of this experiment are to collect and isotopically analyze interstellar gas atoms around the orbit of the Earth for the purpose of obtaining new data relevant to understanding nucleosynthesis, and to study the dynamics of the interstellar wind inside the heliosphere and the isotopic composition of the interstellar medium outside the heliosphere. The experiment hardware will act as a set of simple cameras with high-purity copper-beryllium collecting foils serving as the film. The experiment housing will mount and thermally control the foils, establish the viewing angles and viewing direction, provide baffling to reject ambient neutral particles, provide a voltage grid to reject ionospheric charged particles, sequence collecting foils, control exposure times, and protect the foils from contamination during the deployment and retrieval of the LDEF. After being returned to Earth, the entrapped atoms can be analyzed by mass spectroscopy to determine the relative abundance of the different isotopes of helium and neon. An attempt will also be made to detect argon.
    Schlagwort(e): ASTROPHYSICS
    Materialart: NASA. Langley Research Center Long Duration Exposure Facility (LDEF); p 98-100
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  • 6
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    Introduction to Long-Duration Exposure Facility (1984)
    In:  CASI
    Details
    Publikationsdatum: 2006-02-14
    Beschreibung: A description of the structure and uses of the Long Duration Exposure Facility (LDEF) is given. The LDEF was designed to provide a large number of economical opportunities for science and technology experiments that require modest electrical power and data processing while in space and which benefit from postflight laboratory investigations with the retrieved experiment hardware. Like the Shuttle, the LDEF is reusable, and repeat missions are planned, each with a new complement of experiments. The LDEF is essentially a free-flying cylindrical structure. The experiments on LDEF are totally self-contained in trays mounted on the exterior of the structure. LDEF can accommodate 86 experiment trays, 72 around the circumference and 14 on the two ends. The LDEF is delivered to Earth orbit by the Shuttle. In orbit, the Shuttle remote manipulator system removes the LDEF from the Shuttle payload bay and places it in a gravity-gradient-stabilized attitude. After an extended period in orbit, which is set by experiment requirements, the LDEF is retrieved on a subsequent Shuttle flight.
    Schlagwort(e): ASTRONAUTICS (GENERAL)
    Materialart: NASA. Langley Research Center Long Duration Exposure Facility (LDEF); p 1-5
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  • 7
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    High spatial resolution IR observations of young stellar objects - A possible disk surrounding HL Tauri (1984)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-18
    Beschreibung: High spatial resolution images of the T Tauri star HL Tau were obtained at 1.6 microns and 2.2 microns. The original images as well as maximum entropy image reconstructions reveal a circumstellar envelope structure, similar at both wavelenghts, and extended along P.A. = 112 deg; the 10 percent width of the structure is 1.9 sec (300 AU at 160 pc). The extended structure is interpreted as light scattered toward earth by dust in a disk surrounding this young stellar object. Polarization measurements made at 2.2 microns support this hypothesis. The total solid particle mass is, at minimum, 5 x 10 to the -7th solar mass.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 283; L57-L61
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  • 8
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    Very slow classical Cepheids - Theoretical models with periods longer than 50 days (1984)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-18
    Beschreibung: Systematics of the light curves of classical Cepheids with the longest known periods have been investigated with the help of full-amplitude models of pulsating stellar envelopes. For periods exceeding about 60 days, flat-topped light curves of the S Vul type are found to replace the smooth, asymmetric light curves characteristic of the slightly faster Cepheids. Predicted light and velocity amplitudes (although not the predicted radius amplitudes) agree well with observations. Variables with fluctuating light minima are observed to lie well off the mean period-luminosity relation, as are a few other (more stable?) variables with similarly long periods. The explanation for the long periods is probably low effective temperature rather than a low stellar mass. Because of the abnormal slowness of the classical Cepheids with periods longer than about 100 days, it is recommended that these variables not be used to calibrate the mean period-luminosity relation. Analogies between the slow classical Cepheids and the slow Population II Cepheids are drawn.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 281; 811-814
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  • 9
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    On the '3 kiloparsec arm' - Resonance excitation of linear and nonlinear waves by an oval distortion in the central region (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The mechanism responsible for the massive rapidly expanding Galactic feature known as the 3-kpc arm (Rougoor and Oort, 1960) is investigated theoretically in the framework of a density-wave model of the Galaxy. The arm is attributed to outgoing waves excited at the outer Lindblad resonance (OLR) of a small rotating oval distortion near the Galactic center. Linear and nonlinear models are developed, and it is shown that a density crest at 3.5 kpc with expansion velocity 53 km/s can be generated by a distortion turning at 118 km/s kpc with a 10-percent perturbation of the main gravitational field at the OLR (located at 3 kpc). The wave character of the nonlinear solution is found to be the same as that of the linear solution and to give good agreement with the observations in terms of expansion velocity, size, shape, and mass; only the observed asymmetry of the arm is not reproduced.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 281; 600-613
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  • 10
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    Superclustering and the large-scale structure of the Universe (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: A complete redshift survey of nearby rich galactic clusters is analyzed in terms of a spatial correlation function, the growth of supercluster, the presence of superclusters around the Bootes void and the discovery of a 300 Mpc void. Abell's (1958) statistical sampling of rich clusters is used for the study. Attention is given to the dependence of the correlation function on the richness of the system, with finding that chances are greater of finding rich neighbors closer together than poor neighbors. Samples of redshifts of 4 or less correlate well with clusters of redshift 5 or more. The size of intergalactic voids is proportional to the surrounding galactic excesses. Finally, the superclusters exist on scales of about 100 Mpc/h, which is larger than expected.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Advances in Space Research (ISSN 0273-1177); 3; 10-12
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  • 11
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    Payload crew members' view of Spacelab operations (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Various operational aspects of the Spacelab 1 mission are reviewed by the four payload crew members. Two-shift operations, voice communication with ground investigators, joint participation in experiment activity, Spacelab performance, and recent advances are discussed.
    Schlagwort(e): ASTRONAUTICS (GENERAL)
    Materialart: Science (ISSN 0036-8075); 225; 165-167
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  • 12
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    Ultraviolet spectral morphology of the O stars - The remarkable luminosity dependence of the Si IV stellar wind effect (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: An extensive survey of ultraviolet O type spectra, by means of high-resolution data from the International Ultraviolet Explorer archives, shows a strong correlation between both the photospheric and stellar wind features, and the optical spectral types. In particular, the stellar wind effect in the Si IV resonance doublet displays a strong luminosity dependence which has not been completely described before: there is no effect anywhere on the main sequence, but it develops gradually through the intermediate luminosity classes into a full P Cygni profile in the supergiants. This behavior is in sharp contrast to that of the C IV and N V, which have strong P Cygni profiles throughout most of the O type domain, including the main sequence. The Si IV effect simultaneously provides a sensitive classification criterion and poses an outstanding problem for detailed astrophysical interpretation. In addition, a new emission feature at 1574 A, possibly due to N III or to N IV forbidden line, is reported.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 280; L27-L30
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  • 13
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    Do bipolar magnetic regions exist on the surfaces of early-type stars? (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The observations of relatively narrow absorption components of the UV resonance lines in the spectra of early-type stars are reviewed, and some new observational data are presented for Rho Leo (B1 Ib). It is shown that the discrete components which are seen in the UV resonance lines of early-type stars are a result of ejection from local spots above the photospheres of hot stars. It is suggested that localized ejection is caused by magnetic flux lines associated with a bipolar magnetic region on the surface of the star.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 280; 712-728
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  • 14
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    Models of the hard X-ray spectrum of AM Herculis and implications for the accretion rate (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Phenomenological fits to the hard X-ray spectrum of AM Hercules have failed to explain the high equivalent width (0.8 + or - 0.1 keV) of Fe K-alpha emission. The scattering and fluorescent line production in a cold or partially ionized accretion column of hard X-rays emitted at the base are investigated using the Monte Carlo method. It is shown that the Fe emission equivalent width observed in the spectrum of AM Her can be explained without resorting to an overabundance of Fe in the accreting material. For sufficient optical depth across the accretion column, equivalent widths of K-alpha emission even larger than the observed values can be obtained. The accretion rate and gravitational power can be deduced from the optical depth across the column, if the column size is known, and, together with the observed hard X-ray and polarized light luminosities, imply a lower limit for the luminosity in the UV to soft X-ray range, for which the observations give model-dependent values.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 280; 734-743
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  • 15
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    Disappearance and disintegration of comets (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The present investigation has the objective to provide a summary of the existing evidence on the disappearance of comets and to draw conclusions regarding the physical processes involved in the disappearance. Information concerning the classification of evidence and the causes of apparent disappearance of comets is presented in a table. Attention is given to the dissipating comets, the headless sungrazing comet 1887 I, and the physical behavior of the dissipating comets and the related phenomena. It is found that all comets confined to the planetary region of the solar system decay on astronomically short time scales. However, only some of them appear to perish catastrophically. Some of the observed phenomena could be successfully interpreted. But little insight has been obtained into the character of the processes which the dissipating comets experience.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Icarus (ISSN 0019-1035); 58; 81-100
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  • 16
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    X-ray spectral signatures of accreting black holes (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The X-ray properties of the binary black hole candidates include distinctive bimodal spectral behavior where the X-ray spectra switch between being very soft (alpha greater than 3) and hard (alpha about 0.7). It is pointed out that this spectral transition occurs at about 1 percent L(edd) (for accretion onto a 10 solar masses black hole), and that this corresponds to the luminosity where an optically thick electron-positron pair plasma will form. Active galactic nuclei (AGN) are often considered to be accreting black holes. An X-ray spectral similarity between the above binary sources and both the Seyfert I and BL Lac classes of AGN is demonstrated. As many of these objects radiate most of their luminosity as X-rays, such a similarity may be expected if the underlying mechanisms are similar.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astronomy and Astrophysics (ISSN 0004-6361); 133; 2, Ap
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  • 17
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    Spectral analysis of magnetohydrodynamic fluctuations near interplanetary shocks (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Preliminary results of an investigation of magnetic fluctuations seen upstream of two interplanetary shocks are presented. The spectral analysis includes calculation of the normalized reduced magnetic helicity spectrum, the normalized reduced cross-helicity spectrum, and the Alfven ratio as discussed by Matthaeus and Goldstein (1982). Minimum variance methods are used to compute wave polarization as a function of frequency. The Taylor 'frozen in flow' hypothesis is assumed to convert frequencies to wave vectors. Some of the basic properties of the waves, including the probable mode of propagation in association with both quasi-parallel forward and reverse shocks, are described. A comparison with previous results on the generation of waves at interplanetary and planetary shocks is presented.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Journal of Geophysical Research (ISSN 0148-0227); 89; 3762-377
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  • 18
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    HEAO 3 observations of the Crab pulsar (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The Crab pulsar (PSR 0531+21) is the only pulsar which has been observed throughout almost the entire electromagnetic spectrum from 0.5 keV to over 2000 GeV. In general, the emission from the Crab nebula and its pulsar has been remarkably constant in time (except for the pulsations). However, several recent observations, especially of gamma-ray line emission, indicate possible time variations. The present investigation is concerned with the data obtained with the HEAO C-1 experiment. The data have been studied with the hope of finding information regarding a number of questions, taking into account the existence of line emission from the pulsar, the variation of the shape of the light curve with time, and the spectral variations as a function of pulsar phase. The spectrum of the total phase-averaged pulsed emission is found to be consistent with a single power-law spectrum from 50 keV to 10 MeV.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 278; 784-790
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  • 19
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    X-ray observations of X Persei (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The HEAO 2 Einstein Observatory was used to confirm the identification of 4U 0352 + 30 with X Per. The HEAO 2 data were analyzed in order to determine an additional point in the pulse period history of the X-ray source and to search for short binary periods. In addition, a majority of the historical X-ray observations was reanalyzed and more refined values for the pulse period as a function of time were obtained. The period history possess significant scatter, but no evidence for a measurable long-term spin-up trend is found, and hence a lower limit to the spin-up time scale is set. This lower limit is consistent with the presence of a neutron star, but it does not rule out a degenerate dwarf. The period history was also searched for evidence of binary motion, and upper limits to a(x) sin i were obtained.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 278; 711-715
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  • 20
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    Variable ultraviolet emission in SY Muscae (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The results of continued IUE monitoring of the symbiotic variable SY Muscae, following an earlier report of a radical enhancement in UV emission from the star, are reported. Over the course of one year, the prominent emission lines of N V, O V, C IV, and He II appear to be gradually decreasing in absolute intensity. This appears to coincide with a steady decline in electron density in the emission line forming region. The data are consistent with a sudden ejection event in which material expelled from the surface of a hot subdwarf has exposed the underlying UV continuum of the star. A number of strong emission lines that are photoexcited by the intense radiation field of the secondary also exhibit broad pedestal emission that suggests turbulent velocities of about 150-300 km/s in an expanding shell or possibly in an accretion disk.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Royal Astronomical Society, Monthly Notices (ISSN 0035-8711); 207; 575-583
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  • 21
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    The remarkable ultraviolet spectrum of the planetary nebula Abell 30 (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Abell 30 has been identified as a planetary nebula in which the nucleus has experienced a final helium shell flash after ejection of the original, outer envelope. Around the central star of the nebula, four knots of material are observed. In view of the importance of the chemical composition of the ejected material for studies of advanced stages of stellar evolution, clarification of the physical conditions in the knots is vital. Data obtained of Abell 30 with the aid of the International Ultraviolet Explorer (IUE) satellite are discussed along with aspects of extinction, the He II flux, ionic abundances, the C II lambda 4267 line, questions regarding the existence of a carbon-rich core in the knot, the heating of the nebular gas, the central star, and heating by suprathermal particles from the stellar wind. The UV spectrum of the inner nebulosity of Abell 30 indicates that an extraordinary amount of energy is being deposited in the gas.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 277; 716-724
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  • 22
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    A study of extreme carbon stars. I - Silicon carbide emission features (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: 10-micron spectra of many extreme carbon stars reveal a prominent emission feature near 11 microns. This is compared with laboratory spectra of SiC grains. Two distinct types of features are found, perhaps indicative of different mechanisms of grain formation in different stars. Estimates are made of probable column densities and total masses of SiC in the circumstellar shells.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Royal Astronomical Society, Monthly Notices (ISSN 0035-8711); 206; 137-147
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  • 23
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    MHD processes in the outer heliosphere (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The magnetic field measurements from Voyager and the magnetohydrodynamic (MHD) processes in the outer heliosphere are reviewed. A bibliography of the experimental and theoretical work concerning magnetic fields and plasmas observed in the outer heliosphere is given. Emphasis in this review is on basic concepts and dynamical processes involving the magnetic field. The theory that serves to explain and unify the interplanetary magnetic field and plasma observations is magnetohydrodynamics. Basic physical processes and observations that relate directly to solutions of the MHD equations are emphasized, but obtaining solutions of this complex system of equations involves various assumptions and approximations. The spatial and temporal complexity of the outer heliosphere and some approaches for dealing with this complexity are discussed.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Space Science Reviews (ISSN 0038-6308); 39; 255-316
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  • 24
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    Cosmogony as an extrapolation of magnetospheric research (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: A theory of the origin and evolution of the Solar System which considered electromagnetic forces and plasma effects is revised in light of information supplied by space research. In situ measurements in the magnetospheres and solar wind can be extrapolated outwards in space, to interstellar clouds, and backwards in time, to the formation of the solar system. The first extrapolation leads to a revision of cloud properties essential for the early phases in the formation of stars and solar nebulae. The latter extrapolation facilitates analysis of the cosmogonic processes by extrapolation of magnetospheric phenomena. Pioneer-Voyager observations of the Saturnian rings indicate that essential parts of their structure are fossils from cosmogonic times. By using detailed information from these space missions, it is possible to reconstruct events 4 to 5 billion years ago with an accuracy of a few percent.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Space Science Reviews (ISSN 0038-6308); 39; 65-90
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  • 25
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    Abundances in galactic H II regions. III - G25.4-0.2, G45.5+0.06, M8, S159, and DR 22 (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Measurements of the ARII (6.99 microns), ArIII (8.99 microns), NeI (12.81 microns), SIII (18.71 microns), and SIV (10.51 microns) lines are presented for five compact HII regions along with continuum spectroscopy. From these data and radio data, lower limits to the elemental abundances of Ar, S, and Ne were deduced. The complex G25.4-0.2 is only 5.5 kpc from the galactic center, and is considerably overabundant in all these elements. Complex G45.5+0.06 is at seven kpc from the galactic center, and appears to be approximately consistent with solar abundance. The complex S159 in the Perseus Arm, at 12 kpc from the galactic center, has solar abundance, while M8 in the solar neighborhood may be somewhat overabundant in Ar and Ne. Complex DR 22, at 10 kpc from the galactic center in the Cygnus Arm, is overabundant in Ar. A summary of results from a series of papers on abundances is given.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 285; 174-180
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  • 26
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    Intense X-ray flares from active stellar systems - EV Lacertae and HD 8357 (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The HEAO A-1 Sky Survey Experiment included X-ray data used to define light curves for the flare star EV Lac and for X-ray flares observed in the binary system HD 8357. The data were taken during flare events and were detailed enough to calculate the flare rates and flaring luminosities. The peak luminosities during flares were several times the luminosities in normal X-ray flares emitted by the objects. Peak luminosities reached 30-50 times the normal variations and were associated with an order of magnitude increase in energy output. EV Lac was sufficiently active to be recommended for inclusion in future X-ray monitoring programs.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 284; 270-277
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  • 27
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    Regularized Monte-Carlo calculations of the optical polarization induced by scattering in X-ray binaries (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The results of regularized Monte Carlo calculations of the optical polarization Stokes parameters expected as a result of scattering from gas streams or accretion wakes in close binary systems whose properties resemble those of X-ray binaries are presented. The physical processes occurring in the system are represented by a model which follows a selected sample of individual photon paths from each emitting element on the surface of the primary to the photon's detection at earth. The result represents the variations in the intensity from each individual emitting element caused by the effects of limb darkening, gravity darkening, and variation in the projected area of the emitting element as seen from the scattering element.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astronomy and Astrophysics (ISSN 0004-6361); 138; 1, Se
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  • 28
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    Precession model for the nucleus of periodic Comet Kopff (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The existing data base on certain characteristics of the periodic Comet Kopff, a candidate for a NASA rendezvous mission in the 1990s, is summarized. The comet was discovered in 1906. The data are used to calculate limits to the nuclear mass (0.7-1.5 x 10 to the 16th g), equatorial radius (1.26-1.64 km), and a geometric albedo of 0.08. An equatorial rotation velocity of 8.1-10.7 hr is projected. The estimates are highly dependent on the present photometric data, which in turn depend on the insolation rate, which if different than assumed could mean that all parameters would be revised upward significantly.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astronomical Journal (ISSN 0004-6256); 89; 1573-158
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  • 29
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    The H flux peak and the hydrogen abundance in N type carbon stars (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: For galactic N and late R type irregularly variable carbon stars, a comparison is made of airborne infrared spectrophotometry to spectral flux distributions derived from model atmospheres. Although the agreement is good in several respects, the H(-) emission peak at 1.6 microns, so prominent in the models, is significantly weakened in the stellar spectrophotometry. It seems unlikely that molecular bands in the stars can completely obliterate this peak. A plausible explanation is that hydrogen is deficient in these stars, most probably from an episode of mass loss. The resultant cold shells surrounding these stars should be amenable to observation by IRAS, or other far-infrared observatories.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 284; L39-L42
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  • 30
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    An X-ray survey of variable radio bright quasars (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: A sample consisting primarily of radio bright quasars was observed in X-rays with the Einstein Observatory for times ranging from 1500 to 5000 seconds. Detected sources had luminosities ranging from 0.2 to 41.0 x 10 to the 45th power ergs/sec in the 0.5 to 4.5 keV band. Three of the fourteen objects which were reobserved showed flux increases greater than a factor of two on a time scale greater than six months. No variability was detected during the individual observations. The optical and X-ray luminosities are correlated, which suggests a common origin. However, the relationship (L sub x is approximately L sub op to the (.89 + or - .15) found for historic radio variables may be significantly different than that reported for other radio bright sources. Some of the observed X-ray fluxes were substantially below the predicted self-Compton flux, assuming incoherent synchrotron emission and using VLBI results to constrain the size of the emission region, which suggests relativistic expansion in these sources. Normal CIV emission in two of the sources with an overpredicted Compton component suggests that although they, like BL Lac objects, have highly relativistic material apparently moving at small angle to the line of sight, they have a smaller fraction of the continuum component in the beam.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 284; 491-496
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  • 31
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    Some properties of the filamentary nebula at 1723 - 46 (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: High resolution spectra of the interstellar NaI D2 absorption line have been obtained for seven B-type stars aligned with an extensive filamentary nebula. Very fine filaments have now been found on a high contrast print of a deep H-alpha and forbidden N II plate, making identification as a fossilized remnant probable but uncertain. The inferred age is about 20,000 yr, the distance less than 200 pc, the diameter less than 17.5 pec, but the initial energy is only about 2 x 10 to the 47th erg.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Royal Astronomical Society, Monthly Notices (ISSN 0035-8711); 210; 693-699
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  • 32
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    Grain destruction in interstellar shocks (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The destruction of interstellar grains by nonthermal sputtering, thermal sputtering, and grain-grain collisions is discussed. It is concluded that large grains are easily destroyed by shocks in the interstellar medium, but that small grains are much more persistent. Since the MRN model has many more small grains than large ones, this means that the total number of grains is not significantly reduced even when half or more of the grain material is returned to the gas phase. Thus, the small grains are always available as condensation cores for mantle formation or redepletion of refractory grain materials.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Royal Observatory Lab. and Observational Infrared Spectra of Interstellar Dust; p 26-32
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  • 33
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    Dendritic solidification in a binary alloy melt: Steady-state versus morphological stability theories (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: A model for dendritic growth in a binary alloy melt, in the presence of a positive temperature gradient in the liquid, is presented. The model describes satisfactorily the transition from a dendritic interface to a planar interface at very low and very large growth rates. A dendrite tip stability parameter is derived, strictly from steady state considerations, without resorting to a perturbation analysis. The estimates of the parameter agree with those obtained by models based on perturbation analyses.
    Schlagwort(e): ASTRONAUTICS (GENERAL)
    Materialart: ESA Fifth European Symp. on Mater. Sci. under Microgravity. Results of Spacelab 1; p 403-407
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  • 34
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    Crystal growth of GaAs in space (1984)
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    Publikationsdatum: 2011-08-19
    Beschreibung: It is shown that stoichiometry variations in the GaAs melt during growth constitute the most critical parameter regarding defect formations and their interactions; this defect structure determines all relevant characteristics of GaAs. Convection in the melt leads to stoichiometric variations. Growth in axial magnetic fields reduces convection and permits the study of defect structure. In order to control stoichiometry in space and to accommodate expansion during solidification, a partially confined configuration was developed. A triangular prism is employed to contain the growth melt. This configuration permits the presence of the desired vapor phase in contact with the melt for controlling the melt stoichiometry.
    Schlagwort(e): ASTRONAUTICS (GENERAL)
    Materialart: ESA Fifth European Symp. on Mater. Sci. under Microgravity. Results of Spacelab 1; p 221-225
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  • 35
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    Thermal modeling of Halley's Comet (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The comet thermal model of Weissman and Kieffer is used to calculate gas production rates and other parameters for the 1986 perihelion passages of Halley's Comet. Gas production estimates are very close to revised pre-perihelion estimates by Newburn based on 1910 observations of Halley; the increase in observed gas production post-perihelion may be explained by a variety of factors. The energy contribution from multiply scattered sunlight and thermal emission by coma dust increases the total energy reaching the Halley nucleus at perihelion by a factor of 2.4. The high obliquity of the Halley nucleus found by Sekanina and Larson may help to explain the asymmetry in Halley's gas production rates around perihelion.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Advances in Space Research (ISSN 0273-1177); 4; 9, 19; 221-224
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  • 36
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    IRAS observations of cometary dust (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: It is pointed out that solid material present in the coma and tail of a comet is revealed by the scattering of sunlight and thermal emission of absorbed solar radiation. The large beam size and low background of the cold Infrared Astronomy Satellite (IRAS) telescope make it extremely well suited to the measurement of faint diffuse thermal emission from solid grains associated with comets. The IRAS project was conducted jointly by the Netherlands, the United Kingdom, and the U.S. Its basic objective involved a survey of the sky in four wavelength regions centered on 12, 25, 60, and 100 microns. The present paper is mainly concerned with IRAS observations of the coma-nucleus regions as defined by the maximum in the intensity distribution. Attention is given to circumstances of comet observations, dust production rates, and a discussion of the results.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Advances in Space Research (ISSN 0273-1177); 4; 9, 19
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  • 37
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    A comparison of the dust properties in recent periodic comets (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Measurements of the thermal emission from the cometary dust coma can be used to derive the rate of dust production from the nucleus as well as the size distribution of absorbing grains. More than ten short-period comets have now been observed in the infrared over a wide range in heliocentric distance. Dust production rates are derived for these comets based on theoretical models of the thermal emission from small absorbing grains and calculations of dust grain velocities. The mean size and albedo of the dust grains is similar in these comets, with the exception of Comet Crommelin, which seems to have had larger, darker grains.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Advances in Space Research (ISSN 0273-1177); 4; 9, 19; 189-196
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  • 38
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    A new calibration of the semi-empirical photometric theory for Halley and other comets (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The semiempirical photometric theory of gas and dust production in comets (Newburn, 1979, 1981, and 1982) is recalibrated on the basis of the 17-comet compilation of spectrophotometric data of Newburn and Spinrad (1984). The results are presented in graphs and tables, and it is shown that no corrections are required for the constant R and the function delta, but that the mixing ratios (obtained as functions of heliocentric distance) can be improved, with implications for the visual-photometric comet model. Recently calculated light curves for comet Halley are compared, and the use of the nearly identical curves of Bortle and Morris (1984) and Marcus (1983) is recommended.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Advances in Space Research (ISSN 0273-1177); 4; 9, 19; 185-188
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  • 39
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    Electromagnetic containerless undercooling facility and experiments for the Shuttle (1984)
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    Publikationsdatum: 2011-08-19
    Beschreibung: An electromagnetic furnace is being prepared for flights aboard the Space Shuttle. This apparatus is capable of melting metals and alloys up to 1400 C melting point by induction heating with subsequent solidification of the freely levitated melt without contact with any container. The solidification can be carried out with greatly reduced fields resulting in minimal heating and stirring of the free melt. Sequential specimens can be processed during flight. Several experiments are planned for a series of flights, beginning in 1985 with an undercooling experiment of NiSn alloys. These will be interspersed with detailed studies of fluid flow caused by low and high field levels in order to quantify the corresponding effect upon the solidification process.
    Schlagwort(e): ASTRONAUTICS (GENERAL)
    Materialart: Advances in Space Research (ISSN 0273-1177); 4; 5, 19; 99-103
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  • 40
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    On Bowen enhancement of the N III spectrum under solar and nebular conditions (1984)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Expected enhancement of the N III emission-line spectrum by the Bowen He II to O III to N III resonant photoexcitation process is computed using a six-configuration model. Preliminary comparisons with available solar and nebular observations indicate that the process may play only a small role, although photoexcitation quenching of the N III and O III far-infrared fine-structure lines is noted as a possibly important mechanism. Some features are discussed in connection with the nebular emission at 1750 A, which is suggested as an indicator of excitation class for planetary nebulae.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 287; 945-951
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  • 41
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    The 41.5 day binary X-ray pulsar 4U 1223 - 62 (GX 301 - 2) (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Ariel 5 and SAS 3 X-ray pulse timing data for the 700 s X-ray pulsar 4U 1223 - 62 (GX 301 - 2) are reexamined in order to deduce the orbital elements of this system. The Ariel 5/SAS 3 arrival times are first reanalyzed to obtain the best solution for an orbital period close to 41.5 days and to estimate the uncertainties in it caused by unknown variations in the underlying pulse period. Spectral measurements by OSO 8 and HEAO 1 at a variety of orbital phases are presented and the origin of an unabsorbed, unpulsed soft component is discussed. OSO 8 observations of occasions when the amplitude and shape of the pulse profile changed dramatically are discussed. The global X-ray properties of the system are explained in terms of a simple stellar wind accretion model, and the interaction of the inflowing material with the neutron star magnetosphere is considered.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 287; 856-867
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  • 42
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    Similar photospheres, different mantles - A study of four O stars (1984)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The present investigation is concerned with a comparison of the spectra of four O stars (10 Lac, S Mon, HD 46223, and Zeta Pup) which have similar effective temperatures, taking into account an attempt to find the reason for differences regarding the spectral type of the stars. The photospheres of the stars are examined, taking into account the effective temperatures, radii, speed of rotation, and masses. Information is presented about the equivalent widths and profiles of strong lines in the visible and ultraviolet spectra of each star. It is found that the four stars have similar photospheres but different mantles. The stars are assigned different spectral types because the empirically selected lines used for determining spectral type in class O are sensitive primarily to conditions in the mantle of the star and not to conditions in the photosphere. Questions concerning the reasons for the differences regarding the mantles are also explored.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 287; 874-891
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  • 43
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    Absorption features in the 5-8 micron spectra of protostars (1984)
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    Publikationsdatum: 2011-08-19
    Beschreibung: High signal-to-noise ratio spectra in the range of 5-8 microns of four sources embedded in molecular clouds are examined using low-temperature laboratory measurements of the 5-8-micron spectra of simple molecules and their mixtures. The absorption, apparent in all four sources, is characterized by highly distinct features ranging from two relatively narrow bands at 6.0 and 6.8 microns in W33A to a broad, shallow, and partially structured feature extending from 5.2 to 7.8 microns in Mon R2-IRS2, BN, and NGC2264. The first feature (W33A) is explained by the OH bending mode in H2O and the CH deformation modes in saturated hydrocarbons; while the second feature (Mon R2-IRS2-type) is explained by the presence of a mixture of saturated and unsaturated hydrocarbons possibly containing strongly electronegative groups.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 287; 697-706
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  • 44
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    Self-absorption of high-energy Gamma-rays in Cygnus X-3 (1984)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Absorption of high-energy gamma-rays from Cyg X-3 in its own photon field by the reaction gamma + gamma yields e(+) + e(-) is considered. It is found that gamma rays with an energy around 10 to the 12th eV are attenuated, and the observed flux has to be corrected. Gamma rays with energy greater than 10 to the 15th eV which are observed are not affected by the photon field.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 287; 338-340
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  • 45
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    Monte Carlo shock-like solutions to the Boltzmann equation with collective scattering (1984)
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    Publikationsdatum: 2011-08-19
    Beschreibung: The results of Monte Carlo simulations of steady state shocks generated by a collision operator that isotropizes the particles by means of elastic scattering in some locally defined frame of reference are presented. The simulations include both the back reaction of accelerated particles on the inflowing plasma and the free escape of high-energy particles from finite shocks. Energetic particles are found to be naturally extracted out of the background plasma by the shock process with an efficiency in good quantitative agreement with an earlier analytic approximation (Eichler, 1983 and 1984) and observations (Gosling et al., 1981) of the entire particle spectrum at a quasi-parallel interplanetary shock. The analytic approximation, which allows a self-consistent determination of the effective adiabatic index of the shocked gas, is used to calculate the overall acceleration efficiency and particle spectrum for cases where ultrarelativistic energies are obtained. It is found that shocks of the strength necessary to produce galactic cosmic rays put approximately 15 percent of the shock energy into relativistic particles.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 286; 691-701
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  • 46
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    The collapse of the cores of slowly rotating isothermal clouds (1984)
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    Publikationsdatum: 2011-08-19
    Beschreibung: A generalized model which accounts for the effects of initially uniform and slow rotation is defined for the spherical collapse of a singular isothermal sphere such as protosolar and binary nebulae. An initial unstable equilibrium state is described for a sound speed of 0.35 km/sec and a rotation rate of 10 to the -14th/sec for the molecular cloud surrounding the accreting core. The total angular momentum and mass of the inner cloud is set equal to solar system values. The evolution of the collapse is traced by applying a perturbation analysis to the similarity solution for a nonrotating condition, and matched asymptotic expansions solve the hydrodynamic equations. The model is concluded a valid tool for studying star and nebular disk formation.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 286; 529-551
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  • 47
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    Evidence for a supersonic turbulent velocity gradient in the outer photosphere of the supergiant alpha Cygni (A2Ia) (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The balloon-borne UV Stellar Spectrometer's high resolution, near-UV spectra of the supergiant Alpha Cyg are subjected to analysis in order to determine the average microturbulent line-of-sight velocity component. A value of 15.0 + or - 0.5 km/sec is obtained, which is close to the 13.7 km/sec local sound velocity, and is consistent with the view that shock waves are the dominant structure in the outer photosphere of Deneb, so that shock wave dissipation determines the thermal structure of the photosphere.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astronomy and Astrophysics (ISSN 0004-6361); 141; 2, De
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  • 48
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    Vibrational and rotational excitation of CO in comets Nonequilibrium calculations (1984)
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    Publikationsdatum: 2011-08-19
    Beschreibung: Ultraviolet observations of atomic carbon in cometary comae show that carbon-bearing compounds must comprise a significant fraction (approximately equal to or greater than 10 percent) of the volatiles. One likely source is CO. This compound is an important constituent of at least some cometary nuclei, even though it may not be the ultimate source of atomic carbon in all comets. Feldman (1983) has suggested that the relative abundance of CO may be one of the few fundamental characteristics which distinguish one comet from another. The present investigation is, therefore, concerned with the vibrational and rotational excitation of the CO molecule in cometary comae. Two previously neglected factors are taken into account in the study. The fractional populations of CO as solutions to time-dependent differential equations are derived, and a nonisothermal and cold kinetic temperature profile for the inner coma is considered.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 285; 858-869
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  • 49
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    The ultraviolet variability of early-type supergiants (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Four early-type supergiants - HD 79186 (B5 Ia), HD 96919 (B9 Ia), HD 105056 (ON9.7 Iae), and HD 148379 (B2 Iae) - have been observed with the low-resolution spectrographs of IUE in the large aperture on 14 days. The behavior of the ultraviolet fluxes with time is studied. The light from all four stars seems to vary. Typically the dispersion about the mean magnitude at any wavelength corresponds to + or - 0.085, + or - 0.080, + or - 0.101, and + or - 0.106 mag, respectively. These amplitudes exceed the typical uncertainty in an IUE measurement of flux by about a factor of 3; they are somewhat larger than the variations known in the visible wavelength range. There are insufficient data to investigate periodicity in the observed light changes. The effective temperatures and angular diameters of the stars have been estimated using the present ultraviolet photometry, published UBV and uvby photometry, and the model-atmosphere fluxes reported by Kurucz in 1979. The program stars have dimensions typical for their spectral types. A brief discussion is given of possible causes of the variability of hot supergiants.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 285; 668-673
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  • 50
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    Modification to shock fitting program (1984)
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    Publikationsdatum: 2011-08-19
    Beschreibung: A modified form of the Lepping-Argentiero single spacecraft, shock normal determination procedure is presented. The modified method incorporates a simple predictor-corrector algorithm which allows a faster convergence rate and the use of average values of the parameters for the starting vector.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Journal of Geophysical Research (ISSN 0148-0227); 89; 11004-11
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  • 51
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    Large-scale interplanetary magnetic fields - Voyager 1 and 2 observations between 1 AU and 9.5 AU (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The large-scale radial and temporal variations of the interplanetary magnetic field strength B observed by Voyagers 1 and 2 are discussed. Two components of the magnetic field strength were considered: (1) an average component, B sub zero, based on solar rotation averages, and (2) a fluctuation component, delta B, expressed by 10- or 24-hour averages of B normalized by the best-fit average field for the corresponding time and distance. Observations of the sector structure, interfaces, and shocks are presented to further describe magnetic field strength.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Journal of Geophysical Research (ISSN 0148-0227); 89; 10659-10
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  • 52
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    Cyclotron emission near stellar mass black holes (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Cyclotron emission in the inner regions of an accretion disk around a matter accreting black hole can be appreciable. In the case of the X-ray source Cyg X-1, cyclotron emission may provide the soft photons needed for 'Comptonization' to produce high energy X-rays. The inverse correlation between the fluxes of high energy and low energy X-rays during the 'high' and 'low' states of Cyg X-1, may be understood as a result of the variation of the rate of accretion and the Compton scattering of the cyclotron photons. In the case of the X-ray source GX 339-4, the observed optical flux during the high states does not seem to be due to cyclotron emission, but probably due to reprocessing of high energy X-rays by the outer regions of the disk.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astronomy and Astrophysics (ISSN 0004-6361); 139; 2, Oc
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    Through the tail of a comet (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The instrumentation, trajectory, and missions of the ISEE-3 spacecraft being sent to observe Comet Giacobini-Zimmer (GZ) are described. Originally parked at a libration point to observe the solar wind, ISEE-3 was directed to perform a complex series of flybys of the earth and the moon to move to a trajectory that will intersect the GZ tail in 1985. Renamed ICE, the spacecraft will record magnetic field and charged particle data on the interaction of the cometary tail with the solar wind.
    Schlagwort(e): ASTRONAUTICS (GENERAL)
    Materialart: Spaceflight (ISSN 0038-6340); 26; 405-409
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  • 54
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    Submillimeter wavelength survey of the galactic plane from l = -5 deg to l = +62 deg - Structure and energetics of the inner disk (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: Observational results are presented from a new large-scale survey of the first quadrant of the galactic plane at wavelengths of 150, 250, and 300 microns, with a 10 x 10 arcmin beam. The emission detected in the survey arises from compact sources, most of which are identified with known peaks of 5 GHz or CO emission, or both, and from an underlying diffuse background with a typical angular width of about 0.9 deg (FWHM) which accounts for most of the emission. A total of 80 prominent discrete sources are identified and characterized, of which about half have not previously been reported at far-infrared wavelengths. The total infrared luminosity within the solar circle is about 1 to 2 x 10 to the 10th solar luminosity, and is probably emitted by dust that resides in molecular clouds.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 285; 74-88
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  • 55
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    The variable component of the NGC 4151 IUE spectrum - Evidence for an expanding spherical emission shell (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: The profile of the forbidden line of C III (1909) is the same in two pseudo-trailed, low-resolution SWP spectra of the nucleus of the Seyfert galaxy NGC 4151 obtained with the IUE in November 1980 and December 1982, respectively. In the 1980 spectrum, the C III forbidden line profile is also very nearly the same as that of the resonance line C IV (1550). In the 1982 spectrum, the continuum is 5 times higher and C IV is both much broader and much brighter. In the difference spectrum, which is interpreted to be the spectrum of a time-variable component, C IV (1550) is the only strong emission feature. The profile of this line closely resembles that of a spherical shell surrounding a less dense gas uniformly expanding from a central opaque object. From values of the profile parameters and from the observed time variability of the object, it is inferred that the shell has a radius of about 10 to the 15th cm, a mass of 0.25 solar mass, an expansion velocity of 13,000 km/s, and an electron density of 10 to the 11th per cu cm. From the line profile and the continuum, it is inferred that the opaque central source has approximate radius of 10 to the 14th cm and temperature 23,000 K.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 285; 69-73
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  • 56
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    Gamma rays from atomic and molecular gas in the large complex of clouds in Orion and Monoceros (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: A comparison of COS-B gamma-ray observations of the large complex of interstellar clouds in Orion and Monoceros with the Columbia CO and Berkeley H I surveys of this region reveals a good correlation between gamma-ray emission and total gas distribution. The observed gamma-ray emission is explainable in terms of interactions of cosmic rays that are uniformly distributed in this region with the interstellar gas. The correlation is used as the basis of a calibration of the ratio between H2 column density and the integrated CO line intensity; the value of (2.6 + or - 1.2) X 10 to the 20th mol/sq cm K km s thereby obtained is consistent with the value derived from a similar analysis for the inner galaxy.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astronomy and Astrophysics (ISSN 0004-6361); 139; 1, Oc
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    On the orbit improvement results obtained by referring old cometary observations to the SAO Star Catalog (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-19
    Beschreibung: An algorithm is presented for the automatic reduction to the SAO Star Catalog of old micrometer cometary observations of the type comet minus star. Results of a numerical test are presented showing the distinct influence of such a reduction on orbit determination results.
    Schlagwort(e): ASTROPHYSICS
    Materialart: JPL Cometary Astrometry; p 203-206
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  • 58
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    Scale lengths in quasi-parallel shocks (1984)
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    Publikationsdatum: 2011-08-18
    Beschreibung: A review was carried out of ISEE and Voyager spacecraft magnetometer data to determine if quasi-parallel bow shocks are really broad, disordered regions. The key parameter was the deceleration scale (thickness, Lp) across which random energy would need to increase and a localized electrostatic field (E) would be present. Lp would define the breadth of the shock and be associated with a plasma deceleration. The ISEE 1 satellite collected data on the electron density, bulk speed, magnetic intensity, and electron temperature in November 1977 during five traverses of the bow shock. Similar data were gathered from an interplanetary shock wave in 1981. The evidence supported the concept of a plasma deceleration across a thin layer (Lp) in both types of shocks. The layers were about 50 times (interplanetary) and 20 times (earth) thinner than surrounding magnetic fluctuation regions. It is asserted that the regions of deceleration, although much thinner, are the actual shocks and not the entire regions of magnetic fluctuations.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Journal of Geophysical Research (ISSN 0148-0227); 89; 7545-755
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  • 59
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    Identification of the SiCC radical toward IC +10216 - The first molecular ring in an astronomical source (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: In the radio spectrum of the envelope of the evolved carbon star IRC +10216, the fraction of lines from exotic molecules seldom or never observed in the terrestrial laboratory is exceptionally high. At least 20 lines have not been identified, and it is not known whether one, two, or a number of new molecules are involved. It is shown in the present investigation that nine of the previously unidentified lines in IRC +10216 are produced by SiCC, a radical long known to exist in stellar atmospheres. The true ground-state geometry of this radical has only been obtained recently on the basis of an elegant two-photon ionization experiment in a supersonic molecular beam. Information regarding the molecular geometry and lower rotational levels of SiCC is presented in a graph. The intensities of the SiCC lines confirm the assignments, yield new data on the temperature and density in the envelope of IRC +10216, and indicate that the amount of SiCC there is substantial.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 283; L45-L48
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  • 60
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    Far-infrared and submillimeter survey of the galactic plane from l = 11.5 deg to l = 17.5 deg (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Medium resolution (11 min) maps of the galactic plane are presented from l = 11.5 deg to l = 17.5 deg at wavelengths of 93 microns, 154 microns, and 190 microns. The maps are interpreted in terms of the temperature and spatial structure of diffuse far-infrared/submillimeter sources associated with evolved H II regions and a continuous ridge of galactic emission. The emission regions are found to be more extended at the longer wavelengths which implies that there must be a range of dust temperatures in the sources. The properties of the galactic ridge are similar to those of the sources.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 283; 566-572
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  • 61
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    Mass extinctions and missing matter (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The possible influence of 'invisible matter' on the solar system's comet halo, and therefore on quasi-periodic cometary bombardment of the earth and consequent mass extinctions, is briefly addressed. Invisible matter consisting of small or cold interstellar molecular clouds could significantly modulate the comet background flux, while invisible matter consisting of a large population of old, dead stars with a relatively small galactic concentration probably could not. It is also shown that the downward force exerted by the Galaxy will perturb the halo, but will not produce any periodicity.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Nature (ISSN 0028-0836); 311; 17
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  • 62
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    Space activities - A review and a look ahead (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The paper reviews the progress made in manned and unmanned space programs during the last 25 years and names several major accomplishments. The ingredients of success are identified as good engineering, good technology, and good management of a very complex enterprise. An argument is made that the pace of progress will be governed not by technological advances, which can be very rapid, but rather by future institutional arrangements, which are much slower to evolve. It is predicted that the most likely space activities for the next 20 years will be those relating to space commercialization, and several examples are cited. A hope is expressed that policy makers and entrepreneurs will match the spirit of adventure and risk-taking exhibited by engineers in exploring uncharted territory.
    Schlagwort(e): ASTRONAUTICS (GENERAL)
    Materialart: IEEE Transactions on Aerospace and Electronic Systems (ISSN 0018-9251); AES-20; 311-315
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  • 63
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    The remarkable infrared galaxy Arp 220 = IC 4553 (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: IRAS observations of the peculiar galaxy Arp 220 = IC 4553 show that it is extremely luminous in the far-infrared, with a total luminosity of 2 x 10 to the 12th solar luminosities. The infrared-to-blue luminosity ratio of this galaxy is about 80, which is the largest value of the ratio for galaxies in the UGC catalog, and places it in the range of the 'unidentified' infrared sources recently reported by Houck et al. in the IRAS all-sky survey. Other observations of Arp 220, combined with the luminosity in the infrared, allow either a Seyfert-like or starburst origin for this luminosity.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 283; L1-L4
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  • 64
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    183 GHz water line variation - An energetic outburst in Orion KL (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Observations of the 3(13)-2(20) transition of water vapor in the direction of Ori MC1 in 1980 February show a 50 percent flux increase and an apparent additional red shift of approximately 2 km/s relative to the line observed in 1977 December. From a detailed examination of the amplitude and frequency calibration, it appears unlikely that the effect is due to systematic error. The increase is attributed to the appearance of a new component at a velocity of 12 km/s with respect to the local standard of rest. The new component also has broad wings. Increased emission from a region in the high-velocity core of Ori MC1 can be due either to additional far-IR radiation to pump the 1983 GHz transition or to a change in the physical conditions in the gas. Statistical equilibrium calculations using the large-velocity-gradient formalism were carried out to develop a model for the emission. The calculations support a model in which the gas in the region of enhanced emission is hotter than the dust. The temporal coincidence between the 183 GHz increase and the 22 GH1 water maser outburst suggests a common, impulsive cause, which has heated the gas in a part of the HV source, enhancing the emission in both transitions.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 283; 106-116
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    Remarks on a vibronic origin for the diffuse band spectrum (1984)
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    Publikationsdatum: 2011-08-18
    Beschreibung: It has been demonstrated that the diffuse band spectrum could not originate as a series of vibronic transitions from atomic impurities in interstellar MgO grains as has recently been proposed since laboratory spectra of such materials show no evidence for such complex structure. Furthermore, recent observational evidence indicates that the extinction feature at 160 nm in the standard interstellar extinction curve upon which the identification of interstellar MgO was founded is actually the result of a calibration error in the original observational data.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysics and Space Science (ISSN 0004-640X); 103; 2, Au
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  • 66
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    Space station design - Innovation and compromise (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The NASA manned space station will consist of three main elements: habitable modules, solar collectors, and their interconnecting hardware. The most arduous of the requirements to be met by this configuration is the simultaneous integration of terrestrial, solar, and celestial viewing instruments, since omnidirectional simultaneous viewing is made difficult by the station's large solar energy collection devices. The space station also imposes unique design conditions on individual subsystems, such as the power distribution and energy storage hardware. In particular, the thermal control subsystem must be designed to meet a variety of mission, payload, and housekeeping tasks that demand a large heat rejection capacity. Novel environmental control and life support subsystem technology will be indispensable.
    Schlagwort(e): ASTRONAUTICS (GENERAL)
    Materialart: Aerospace America (ISSN 0740-722X); 22; 70-72
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    Interplanetary radio storms. I - Extension of solar active regions through the interplanetary medium (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: About 100 storms of type-III solar radio bursts have been identified in the ISEE-3 radio-experiment data during the 4-yr period around the maximum of the 21st solar cycle. They demonstrate the very frequent presence of streams of suprathermal electrons. Their durations range from 1 to 10 d or more. They are observed up to 100-170 solar radii. Their rate of occurrence is 2 to 3 per solar rotation near solar maximum. It is shown that the time variations of the daily radio-emission intensities correlate with the sunspot-number variations and with the solar activity in general. More specifically, a very good correlation is found with the meter-wave type-III and type-I storms, which demonstrates that the suprathermal electrons responsible for the radio emission have been accelerated below 2 solar radii heliocentric. The different lags observed between the sunspot-number variations, the S-component, and the type-I and type-III storms are discussed.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astronomy and Astrophysics (ISSN 0004-6361); 136; 2, Ju
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  • 68
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    Mass ejection from the peculiar emission star R Aquarii (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: It is pointed out that the composite emission object R Aquarii embodies a number of characteristic properties which distinguish it from other peculiar emission stars. The visual spectrum indicates the presence of a cool Mira variable in close association with a hot unresolved ionizing source of radiation which appears to be responsible for the high excitation nebular emission observed. It has been suggested by Hubble (1943) and Baade (1944) that the distinguishing meniscus-shaped nebula was formed by a nova outburst which occurred about 600 years ago. Wallerstein and Greenstein (1980) reported the appearance of a new feature in R Aquarii which resembles a brilliant 'spike' or 'jet' protruding a distance approximately 7 arcsec from the central compact region. Attention is given to several models which have been considered to explain the emission feature.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Comments on Modern Physics, Part C - Comments on Astrophysics (ISSN 0146-2970); 10; 85-96
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  • 69
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    The v = 0 - 0 spectrum of H2 (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Ground-state rotational parameters for molecular hydrogen are evaluated using a combination of laboratory and observational data. High-accuracy v = 0 - 0 S(0)-S(5) frequencies from infrared laboratory measurements are analyzed simultaneously with available observed frequencies for the S(8), S(9), S(12), S(13), S(14), and S(15) Orion emission lines. The laboratory and Orion measurements are consistent with each other within their measurement errors. The combined data set yields a determination of five v = 0 rotational parameters and an improvement in the high-J calculated line positions. The analysis produces the parameters (in per cm): B(0) = 59.334627(30), D(0) = 0.0456912(30), H(0) = 4.8974(90) x 10 to the -5th, L(0) = -6.320(110) x 10 to the -8th, M(0) = 7.19(30) x 10 to the -11th, where a correction is made for the estimated contribution of sixth and higher orders.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 282; L85-L88
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  • 70
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    Tribology experiment in zero gravity (1984)
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    Publikationsdatum: 2011-08-18
    Beschreibung: A tribology experiment in zero gravity was performed during the orbital flight of Spacelab 1 to study the motion of liquid lubricants over solid surfaces. The absence of a significant gravitational force facilitates studies of the motion of liquid lubricants over solid surfaces as controlled by interfacial and capillary forces. Observations were made of phenomena associated with the liquid on one solid surface and also with the liquid between a pair of closely spaced surfaces. Typical photographic records obtained on Spacelab 1 are described.
    Schlagwort(e): ASTRONAUTICS (GENERAL)
    Materialart: Science (ISSN 0036-8075); 225; 202
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    The Spacelab experience - A synopsis (1984)
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    Publikationsdatum: 2011-08-18
    Beschreibung: The Spacelab 1 mission took place during the period Nov. 28 through Dec. 8, 1983. An overview of the first flight of the orbiting laboratory is presented.
    Schlagwort(e): ASTRONAUTICS (GENERAL)
    Materialart: Science (ISSN 0036-8075); 225; 163-165
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  • 72
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    Flatness of the universe - Reconciling theoretical prejudices with observational data (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Theoretical prejudices argue strongly for a flat universe; however, observations do not support this view. It is pointed out that this apparent conflict could be resolved if the mass density of the universe today were dominated by (1) relativistic particles produced by the recent decay of massive, relic particle species, or by (2) a relic cosmological constant. Scenario (1) has several advantages in the context of galaxy formation, but must confront the problem of a young universe.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Physical Review Letters (ISSN 0031-9007); 52; 2090-209
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  • 73
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    Binary modulation and transient periodic variations in X-ray emission from the AM Her binary H 0139 - 68 (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: A detailed timing analysis of HEAO-1 and Einstein satellite soft X-ray data on the AM Her-type binary H 0139 - 68 indicates that the X-ray flux is modulated at the 113.6363-min period of its optical counterpart, and that the X-ray source shows high and low states. Transient X-ray pulsations with a period of about 275 sec are noted in the Imaging Proportional Counter (IPC) data during the high state, and the rapid X-ray flickering observed in the IPC light curve is characterized by an average e-folding autocorrelation time of about 10-20 sec. The present optical and X-ray data preclude the presence of an accretion disk in the primary system.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Royal Astronomical Society, Monthly Notices (ISSN 0035-8711); 208; 679-685
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  • 74
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    The unusual 8-13 micron spectrum of Markarian 231 (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: An 8-13 micron spectrum was obtained of the Seyfert galaxy Markarian 231 with a spectral resolution of 0.22 micron per point. The spectrum is unlike any previously published spectrum at these wavelengths. The spectrum can be attributed to a combination of absorption and reemission by crystalline silicates which must have formed under conditions quite different from those in which silicates form in the Galaxy. Comparison of the data with previously published data indicates that the infrared emission is extended and not dominated by a bright central source.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 281; L17-L19
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  • 75
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    A formula for the Shakura-Sunyaev turbulent viscosity parameter (1984)
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    Publikationsdatum: 2011-08-18
    Beschreibung: A formula for the Shakura-Suniaev alpha parameter is proposed in terms of the growth rate of the unstable modes of the physical mechanisms that generates turbulence. Turbulent convection is discussed as a particular example. The effect of rotation on turbulent viscosity is considered, and some remarks are made on convective fluxes, disk stability, and other types of instabilities.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 280; L55-L58
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    Soft X-ray spectral observations of quasars and high X-ray luminosity Seyfert galaxies (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Results of the analysis of 28 Einstein SSS observations of 15 high X-ray luminosity (L(x) 10 to the 435 power erg/s) quasars and Seyfert type 1 nuclei are presented. The 0.75-4.5 keV spectra are in general well fit by a simple model consisting of a power law plus absorption by cold gas. The average spectral index alpha is 0.66 + or -0.36, consistent with alpha for the spectrum of these objects above 2 keV. In all but one case, no evidence was found for intrinsic absorption, with an upper limit of 2 x 10 to the 21st power/sq cm. Neither was evidence found for partial covering of the active nucleus by dense, cold matter (N sub H greater than 10 to the 22nd power/sq cm); the average upper limit on the partial covering fraction is 0.5. There is no obvious correlation between spectral index and 0.75-4.5 keV X-ray luminosity (which ranges from 3 x 10 to the 43rd to 47th powers erg/s) or with other source properties. The lack of intrinsic X-ray absorption allows us to place constraints on the density and temperature of the broad-line emission region, and narrow line emission region, and the intergalactic medium. Previously announced in STAR as N84-14082
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 280; 499-515
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    The formation of stellar systems from interstellar molecular clouds (1984)
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    Publikationsdatum: 2011-08-18
    Beschreibung: The observational and theoretical study of regions of continuing star formation promises greater insight into the physical conditions and events associated with the formation of the solar system, and elucidates the role played by star formation in the evolutionary cycle which seems to dominate interstellar material's processing by successive generations of stars in the spiral galaxies. Novel astronomical methods incorporated by the new facilities scheduled for development in the 1980s may yield substantial advancements in star formation process theory; most significant among these efforts will be the identification and examination of the elusive protostellar collapse phase of both star and planetary system formation.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Science (ISSN 0036-8075); 224; 823-830
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    Models of four highly obscured compact H II regions (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Models are constructed for three stars in order to determine their properties and elemental abundances through comparisons of model predictions and observations. By comparing predicted line fluxes with those observed, it is noted that oxygen is apparently enhanced by a factor of 2 in W3A, and of 4 in G75.84 + 0.40A and G29.9 - 0.0. The first two cases are based on the premise that the O(++)-emitting regions are as clumped as those of S(++). The H II regions all need more than one main sequence star or one unusually large star to provide the observed radio luminosity.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 281; 184-193
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  • 79
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    Solar radio burst and in situ determination of interplanetary electron density (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: A few interplanetary electron density scales which were derived from the analysis of interplanetary solar radio burst are discussed and compared to a model derived from 1974 to 1980 Helios 1 and 2 in situ density observations made in the 0.3 to 1.0 AU range. The Helios densities were normalized to 1976 with the aid of IMP and ISEE data at 1 AU, and were then sorted into 0.1 AU bins and logarithmically averaged within each bin. The best fit to these 1976-normalized, bin averages is in N(R(AU)) = 6.1 R(-2.10)/cu cm. This model is in rather good agreement with the solar burst determination if the radiation is assumed to be on the second harmonic of the plasma frequency. This analysis also suggests that the radio emissions tend to be produced in regions denser than the average where the density gradient decreases faster with distance than the observed R(-2.10). Previously announced in STAR as N83-35989
    Schlagwort(e): ASTROPHYSICS
    Materialart: Solar Physics (ISSN 0038-0938); 90; 401-412
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  • 80
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    Evidence for variability of the hard X-ray feature in the Hercules X-1 energy spectrum (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: The hard X-ray spectrum of HER X-1 was measured for the first time with a high resolution (1.4 keV FWHM) germanium spectrometer. The observation was performed near the peak of the on-state in the 35 day cycle and the 1.24 pulsations were observed between the energies of 20 keV and 70 keV. The feature corresponds to an excess of 7.5 sigma over the low energy continuum. Smooth continuum models are poor fits to the entire energy range (chance probabilities of 2 percent or less). The best fit energies are 35 keV for an absorption line and 39 keV for an emission line. These are significantly lower energies than those derived from previous experiments. A direct comparison of the data with the results of the MPI/AIT group shows statistically significant variations which strongly suggest variability in the source. Previously announced in STAR as N83-37036
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 279; 177-183
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  • 81
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    The detection of the 5577.3 A forbidden line of O I in comets (1984)
    In:  Other Sources
    Details
    Publikationsdatum: 2011-08-18
    Beschreibung: The spectral synthesis of C2 Swan band sequence Delta V = -1 indicates the intensity of the forbidden green oxygen line of 5577.3 A to be about 3 to 5 percent of the 6300 A line. Therefore, it appears that the green line should be observable in high-resolution spectra of a bright comet. Festou and Feldman suggest red/green greater than or equal to 10 means a water parent origin.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Earth, Moon, and Planets (ISSN 0167-9295); 30; 105-110
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  • 82
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    Discovery of a shell around Alpha Lyrae (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: IRAS observations of Alpha Lyrae reveal a large infrared excess beyond 12 microns. The excess over an extrapolation of a 10,000 K blackbody is a factor of 1.3 at 25 microns, 7 at 60 microns, and 16 at 100 microns. The source of 60 microns emission has a diameter of about 20 arcsec. This is the first detection of a large infrared excess from a main-sequence star without significant mass loss. The most likely origin of the excess is thermal radiation from solid particles more than a millimeter in radius, located approximately 85 AU from Alpha Lyr and heated by the star to an equilibrium temperature of 85 K. These results provide the first direct evidence outside of the solar system for the growth of large particles from the residual of the prenatal cloud of gas and dust.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 278; L23-L27
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  • 83
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    IRAS observations near young objects with bipolar outflows L1551 and HH 46-47 (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: A 6-solar luminosity dust-embedded precursor of a low-mass (about 1 solar mass) pre-main-sequence star has been discovered with IRAS near the northeast lobe of the bipolar outflow region in the dust cloud L1551 and designated L1551 NE. Star formation is proceeding in at least two locations in L1551, reminiscent of the situation in regions of more massive star formation. If the position of NE in the flow from IRS 5 is indicative of the flow having initiated star formation in NE, then the object can be only about 24,000 years old. Alternatively, NE could appear by chance to lie in the flow from IRS 5. In the globule ES 0210-6A, a 12 solar luminosity dust-embedded precursor of a low-mass (about 1 solar mass) pre-main-sequence star is found which drives the bipolar flow responsible for the string of Herbig-Haro objects HH 46-47 A-D. In this globule, there is only one region of active star formation.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 278; L49-L52
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  • 84
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    The formation of solar type stars - IRAS observations of the dark cloud Barnard 5 (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Observations of the dark cloud Barnard 5 show two compact sources of radiation within the dense core. IRS 1 is associated with 30-800 K dust, has a total luminosity of about 10 solar luminosities, and is presumably a newly formed star of roughly solar mass. IRS 2 has a much cooler color temperature, approximately 25 K, and emits only 1.3 solar luminosities. Its status is unclear, but IRS 2 may be at a very early stage of gravitational collapse or a density enhancement within the cloud heated by the interstellar radiation field. Also within the confines of the cloud are two point sources, which, if associated with the cloud, each emit about 0.5 solar luminosities in the IRAS bands. These may be T Tauri stars, separated from the cloud but still enshrouded in dust shells.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 278; L45-L48
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  • 85
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    IRAS observations of radio-quiet and radio-loud quasars (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Observations from 12 to 100 microns are presented of two radio-quiet and three radio-loud quasars. Over this wavelength range, all five have grossly similar continuum energy distributions. The continua of the radio-loud quasars are consistent with synchrotron radiation. There is an indication, however, of excess 100 micron emission in the two radio-quiet quasars.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 278; L83-L85
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  • 86
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    IRAS observations of Shapley-Ames galaxies (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: A preliminary discussion of the infrared properties of a representative subsample of galaxies in the Revised Shapley-Ames Catalog (B less than about 13 mag) is presented. Of the 165 galaxies in the sample, 108 predominantly spiral galaxies, are detected in the infrared by IRAS. None of the elliptical galaxies and only about 25 percent of the lenticular galaxies scanned were detected. The range of infrared-to-blue luminosity ratios, a measure of the infrared excess of galaxies, is large, varying from roughly 0.1 to roughly 5. The data suggest that weakly infrared emitting galaxies are cool (100-60 micron color temperatures of about 25 K), while the more infrared luminous ones tend to be warmer (about 50 K). The rate of star formation in barred spiral galaxies is apparently higher than in normal spirals. About 1 solar mass/year of interstellar matter is converted into massive stars in the typical spiral galaxy.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 278; L67-L70
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  • 87
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    Carbon and oxygen isotope fractionation in dense interstellar clouds (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: It is pointed out that isotope fractionation as a result of chemical reactions is due to the small zero-point energy differences between reactants and products of isotopically distinct species. Only at temperatures near absolute zero does this energy difference become significant. Favorable conditions for isotope fractionation on the considered basis exist in space within dense interstellar clouds. Temperatures of approximately 10 K may occur in these clouds. Under such conditions, ion-molecule reactions have the potential to distribute isotopes of hydrogen, carbon, oxygen unequally among the interstellar molecules. The present investigation makes use of a detailed model of the time-dependent chemistry of dense interstellar clouds to study cosmological isotope fractionation. Attention is given to fractionation chemistry and the calculation of rate parameters, the isotope fractionation results, and a comparison of theoretical results with observational data.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 1 (ISSN 0004-637X); 277; 581-590
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  • 88
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    The microwave background temperature at 2.64 and 1.32 millimeters (1984)
    In:  Other Sources
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    Publikationsdatum: 2011-08-18
    Beschreibung: Very high signal-to-noise observations of the 3874 A band of interstellar CN toward Zeta Oph are presented. Measurements are conducted of equivalent widths for the R(0), R(1), R(2), and P(1) lines which agree with previous photoelectric, but not photographic, findings. Corrected for saturation, these strengths yield excitation temperatures of 2.73 + or - 0.04 K and 2.8 + or - 0.3 K for the J = 0 to 1 and J = 1 to 2 rotational transitions at 2.64 mm and 1.32 mm respectively. Since the cosmic microwave background radiation (CMB) is primarily responsible for populating the excited rotational levels of interstellar CN toward Zeta Oph, these values are actually upper limits on the CMB brightness temperature at 2.64 mm and 1.32 mm. The results are consistent with a 2.7 K blackbody spectrum for the CMB and do not support the spectral deviations observed near these wavelengths by Woody and Richards.
    Schlagwort(e): ASTROPHYSICS
    Materialart: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 276; L1-L3
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  • 89
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    Space based OTV servicing (1984)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: Space based servicing of an orbit transfer vehicle (OTV) was previously outlined in sufficient detail to arrive at OTV and support system servicing requirements. Needed space station facilities and their functional requirements were identified. The impact of logistics and space serviceable design on the OTV design is detailed herein. RL10 derivative rocket engine inspection task times are enumerated.
    Schlagwort(e): ASTRONAUTICS (GENERAL)
    Materialart: NASA. Lewis Research Center OTV Propulsion Issues; p 255-272
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  • 90
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    Design and implementation of a low-gravity solidification experiment package for the F-104 (1984)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: The use of the F-104 Interceptor for low gravity materials processing experiments is extended to include alloy solidification studies above 1000 C. The F-104 can provide up to 60 seconds of low gravity, but requires a unique experiment package for integration into the aircraft, both physically and electronically. The current research with the F-104 experimental furnace system which has been used to process cast iron samples is described. Results demonstrate the capability of the facility and its operation.
    Schlagwort(e): ASTRONAUTICS (GENERAL)
    Materialart: 2nd Symp. on Space Industrialization; p 362-367
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  • 91
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    Space commercialization: Analysis of R and D investments with long time horizons (1984)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: By following a single hypothetical example through a series of variations, the way different potential investors might look at the opportunity to participate in space commercialization is described. The example itself is fairly typical of commercial opportunities in space. The chief characteristics are a steadily increasing requirement for capital infusion over an 8 year period, followed by a very generous stream of profits running another decade or more beyond. There is a decision point at 3 years, at the conclusion of laboratory R&D; and another at 6 years, following 2 initial space flights.
    Schlagwort(e): ASTRONAUTICS (GENERAL)
    Materialart: NASA. Marshall Space Flight Center 2nd Symp. on Space Industrialization; p 350-361
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  • 92
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    Commercializing the transfer orbit stage (1984)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: Key milestones necessary to establish the transfer orbit stage are examined. The selection of the project concept and synthesis of the company are described followed by an analysis venture capability support and the selection of a major aerospace company as prime contractor. A landmark agreement with NASA sanctioned the commercial TOS concept and provided the critical support necessary to raise the next round of venture capital. Project management and customer commitments are also discussed.
    Schlagwort(e): ASTRONAUTICS (GENERAL)
    Materialart: NASA. Marshall Space Flight Center 2nd Symp. on Space Industrialization; p 342-347
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  • 93
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    Critical point wetting drop tower experiment (1984)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: Preliminary results for the Critical Point Wetting CPW Drop Tower Experiment are produced with immiscible systems. Much of the observed phenomena conformed to the anticipated behavior. More drops will be needed to test the CPW theory with these immiscible systems.
    Schlagwort(e): ASTRONAUTICS (GENERAL)
    Materialart: NASA. Marshall Space Flight Center 2nd Symp. on Space Industrialization; p 306-319
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  • 94
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    Developing commercial users of space (1984)
    In:  Other Sources
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    Publikationsdatum: 2016-06-07
    Beschreibung: The use of low gravity in the development of new products is examined. Low gravity fundaments are presented clearly and simply. A display of past low gravity experiments highlights some of these precepts which are followed by a description of where and how the commercial user can fly his experiment or process.
    Schlagwort(e): ASTRONAUTICS (GENERAL)
    Materialart: NASA. Marshall Space Flight Center 2nd Symp. on Space Industrialization; p 305
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  • 95
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    Purification of biomaterials by phase partitioning (1984)
    In:  Other Sources
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    Publikationsdatum: 2016-06-07
    Beschreibung: A technique which is particularly suited to microgravity environments and which is potentially more powerful than electrophoresis is phase partitioning. Phase partitioning is purification by partitioning between the two immiscible aqueous layers formed by solution of the polymers poly(ethylene glycol) and dextran in water. This technique proved to be very useful for separations in one-g but is limited for cells because the cells are more dense than the phase solutions thus tend to sediment to the bottom of the container before reaching equilibrium with the preferred phase. There are three phases to work in this area: synthesis of new polymers for affinity phase partitioning; development of automated apparatus for ground-based separations; and design of apparatus for performing simple phase partitioning space experiments, including examination of mechanisms for separating phases in the absence of gravity.
    Schlagwort(e): ASTRONAUTICS (GENERAL)
    Materialart: NASA. Marshall Space Flight Center 2nd Symp. on Space Industrialization; p 304
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  • 96
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    Project Explorer (1984)
    In:  Other Sources
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    Publikationsdatum: 2016-06-07
    Beschreibung: PROJECT EXPLORER is a program that will fly student-developed experiments onboard the Space Shuttle in NASA's Get-Away Special (GAS) containers. The program is co-sponsored by the Alabama Space and Rocket Center, the Alabama-Mississippi Section of the American Institute of Aeronautics and Astronautics, Alabama A&M University and requires extensive support by the University of Alabama in Huntsville. A unique feature of this project will demonstrate transmissions to ground stations on amateur radio frequencies in English language. Experiments Nos. 1, 2, and 3 use the microgravity of space flight to study the solidification of lead-antimony and aluminum-copper alloys, the growth of potassium-tetracyanoplatinate hydrate crystals in an aqueous solution, and the germination of radish seeds. Flight results will be compared with Earth-based data. Experiment No. 4 features radio transmission and will also provide timing for the start of all other experiments. A microprocessor will obtain real-time data from all experiments as well as temperature and pressure measurements taken inside the canister. These data will be transmitted on previously announced amateur radio frequencies after they have been converted into the English language by a digitalker for general reception.
    Schlagwort(e): ASTRONAUTICS (GENERAL)
    Materialart: NASA. Marshall Space Flight Center 2nd Symp. on Space Industrialization; p 292
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  • 97
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    Commercial space services (1984)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: An overview of space service opportunities as identified by a Wyle Laboratories' research team is given. Through the use of a baseline space scenario, a variety of space hardware, services, and commercial activities are identified and related on a time-phased basis. A model is presented to relate the potential functions of government and the private sector in a commercialized space environment during the period 1984 to 2004. Barriers, incentives and key issues are likewise identified and addressed to aid in the implementation of private sector activities for spacerelated programs. Broader awareness, legislative actions, incentive development and benefit analyses are considered in the presentation. The time-phased plan provides a useful planning and management tool, allows broader communication, and supports overall space commercialization program assessment.
    Schlagwort(e): ASTRONAUTICS (GENERAL)
    Materialart: NASA. Marshall Space Flight Center 2nd Symp. on Space Industrialization; p 272-274
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  • 98
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    Microgravity containerless processing in long drop tubes (1984)
    In:  CASI
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    Publikationsdatum: 2016-06-07
    Beschreibung: Extensive experience in utilizing long drop tubes for studying effects of microgravity on the solidification of alloys was obtained. While some modifications are necessary to improve versatility, the facility proved to be most useful. Both an electron beam furnace and an electromagnetic levitation furnace can be used. The electron beam furnace is used with vacuum environments (0.00001 torr), whereas the levitation furnace is presently used only in inert gas environments (above 100 torr). Experiments are best applied to refractory alloys because of the sensitivity of the detectors now being used to observe solidification. Processing of lower melting point metals and alloys simply cannot be recorded. On the other hand, expected improvements in detector sensitivity will allow experimentation with relatively low melting alloys. In such cases, solidification will occur in flight only if higher inert gas pressure is used (100 to 760 torr) to increase heat loss by convection. Under these conditions microgravity conditions no longer apply. However, as shown by results to date, it is not microgravity as such that is important in drop tube solidification. Instead it is the containerless nature of the process that is significant, leading to large degrees of undercooling before solidification and therefore to unique alloys.
    Schlagwort(e): ASTRONAUTICS (GENERAL)
    Materialart: 2nd Symp. on Space Industrialization; p 243-259
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  • 99
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    A versatile structure for GAS payloads (1984)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: A strong, square cross-section, central column to which experimental and accessory compartments are attached is described. The attachment may be by direct bolting or through vibration and/or thermal isolators, as needed. Structural and thermal characteristics are evaluated.
    Schlagwort(e): ASTRONAUTICS (GENERAL)
    Materialart: NASA. Goddard Space Flight Center Get Away Spec. Expt. Symp.; p 127-134
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  • 100
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    Ultralight reactive metal foams produced as structural shapes in space: System design (1984)
    In:  CASI
    Details
    Publikationsdatum: 2016-06-07
    Beschreibung: This autonomous experiment for foaming metals in space involved: (1) payload support structure; (2) furnace and foaming apparatus; (3) electronic controls; (4) battery power; and (5) metallurgy. Emphasis was laid on a modular design which was easily modifiable and which offered maximum durability, safety, and failure tolerance.
    Schlagwort(e): ASTRONAUTICS (GENERAL)
    Materialart: NASA. Goddard Space Flight Center Get Away Spec. Expt. Symp.; p 143-150
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