ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • ASTROPHYSICS  (1,144)
  • 2010-2014
  • 1980-1984  (1,144)
  • 1950-1954
  • 1981  (578)
  • 1980  (566)
  • 101
    facet.materialart.
    Unknown
    Production of carbon, sulfur, and CS in Comet West (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Results from ultraviolet spectrographic observations of Comet West (1975n) in the 1620-3960 A wavelength range are presented. Objective grating imagery of the comet reveals for the first time emission from sulfur atoms and CS molecules as well as previously observed lines or bands in carbon atoms and CO(+), CO2(+) and OH molecules. Some evidence exists for emission in the C2 Mulliken bands and in the CO Cameron bands. On the basis of the observations, production rates of C (ground state), C(1D), S, and CS are inferred to be 3.8 x 10 to the 29th per sec, 4.4 x 10 to the 29th per sec, 1.7 x 10 to the 28th per sec, and greater than approximately 3.1 x 10 to the 27th per sec, respectively.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 242
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 102
    facet.materialart.
    Unknown
    The diffuse gamma-ray background in the Hoyle-Narlikar cosmology (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The paper analyzes the contributions of QSOs, BL-Lac objects and Seyfert galaxies to the diffuse gamma-ray background within the framework of the Hoyle-Narlikar theory. It is shown that the inconsistency reported in standard theory, namely that the evolutionary function needed to explain the gamma-ray data is very different from the one derived from the optical part of the spectrum, is no longer present. It is also shown that the contribution of a variable gravitational 'constant' to the expression for the diffuse background is the same as that of a density evolution function.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 92; 1-2,; Dec. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 103
    facet.materialart.
    Unknown
    Neutrino, gamma-ray, electron, and positron production in an ultrarelativistic plasma (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Neutrino, gamma-ray, electron and positron production resulting from inelastic proton-proton collisions in a highly relativistic plasma such as may exist in extragalactic radio or gamma-ray burst sources is examined. The source functions of primary (pions, kaons, and neutrons) and secondary (photons, electrons, positrons and neutrinos) products of relativistic nuclear collisions are computed for the cases of power law and Maxwellian relativistic proton distributions. It is shown that in plasma which is optically thin to interactions between the plasma and secondary gamma-rays, electrons and positrons, only a small fraction of the initial energy is emitted in the observable form of neutrinos and gamma rays. In an optically thick plasma on the other hand, most of the energy of the relativistic protons is found to be equally divided between gamma rays and neutrinos, although only the neutrinos may escape freely to be observed.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 241
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 104
    facet.materialart.
    Unknown
    Dust-to-gas ratio in the outer regions of spiral galaxies (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Some spiral galaxies are surrounded by extended clouds of neutral hydrogen; if dust is associated with this gas, the dust should appear as a faint extended reflection nebula illuminated by the light from the entire galaxy. It is suggested that observations of the surface brightness of the outer regions of M83 and M101 could be worthwhile, since these two galaxies are bright and have extended surrounding gas clouds. Such studies would be of interest with regard to the possible presence of faint extended halos of stars around galaxies, the extent of the metallicity gradients in galaxies, and the value of the dust-to-gas ratio in quasar absorption-line systems.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 241
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 105
    facet.materialart.
    Unknown
    X-ray observations of Algol (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The Solid State Spectrometer on Einstein has been used to study Algol. Two observations six months apart were made, both including a primary optical eclipse. No corresponding X-ray eclipses were seen. During the second observation the source was flaring and was on the average a factor of three brighter. The spectrum on both occasions was consistent with a two-component thermal equilibrium model with temperatures of approximately 7.5 and 40 million degrees. Attempts to insert a third component indicate the temperature distribution to be bimodal. Models for the X-ray emission are discussed and it is suggested that it most likely originates from an active corona surrounding the K star.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 239
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 106
    facet.materialart.
    Unknown
    Far-infrared spectra of W51-IRS 2 and W49 NW (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Measurements of the far-infrared spectra of the powerful H II regions W51-IRS 2 and W49 NW from 65 to 345 per cm with about 9 per cm resolution were obtained by using an airborne Michelson interferometer. The most remarkable feature of the far-infrared spectra of the two regions is the smoothness of the continuum; no evidence is found in the spectra for features of H2O ice at 45 and 62 microns. The spectrum of W51 is well fitted by a 70 K blackbody with a diameter of 14 arc sec, but the spectrum of W49 NW is narrower than a blackbody. The implications of the apparently high peak optical depths of these sources are discussed.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 238
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 107
    facet.materialart.
    Unknown
    Stellar winds, supernovae, and the origin of the H I supershells (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: It is shown that the H I shells and supershells, recently reported by Heiles, are a natural by-product of the interaction of the stellar winds and supernovae, originating from stars in typical OB associations, with the surrounding interstellar medium. The validity of this model is supported by its ability to reproduce observed characteristics of the shells such as the shell sizes and shapes as a function of their distances from the galactic center. This process may also be responsible for injecting synthesized elements into the galactic halo.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 238
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 108
    facet.materialart.
    Unknown
    The evolution of the dust shell of Nova Serpentis 1978 (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Photometric measurements of Nova Serpentis 1978 from V to 19.5 microns covering the first 240 days of the nova's development are reported. A free-free expansion phase was followed by the condensation of a dust shell that became optically thick at both visible and infrared wavelengths. Carbon grains grew to radii of approximately 0.3 microns during the condensation period. The grains appeared to sputter or evaporate for a period of approximately 100 days following infrared maximum. It is found that the condensed carbon comprised 2% of the ejected mass, which implies that carbon abundance was enhanced in the nova shell. The angular expansion rate of the shell yields a distance of approximately 5 kpc and a luminosity of approximately 3000 solar luminosities for Nova Serpentis 1978.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 237
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 109
    facet.materialart.
    Unknown
    Cosmological considerations on the diffuse gamma-ray isotropic background (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Bignami et al (1979) have recently studied the problem of the origin of the diffuse gamma-ray isotropic radiation. They have concluded that within standard cosmology with Lambda = 0 and p = 0, BL Lacertae objects and Seyfert galaxies can account for most of the diffuse radiation if they have not evolved in time. For QSOs, an evolutionary factor is allowed by the data. From the study of radio data, however, it is known that strong evolutionary effects are expected. The discrepancy cannot be explained by changing the geometry of the universe. Contrary to the case of standard cosmology, it is found that in order to fit the diffuse gamma-ray background, the evolutionary function required is almost identical to the one previously determined from the study of the log N-log S relation.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 235
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 110
    facet.materialart.
    Unknown
    On stellar wind accretion in widely separated X-ray binaries, and the nature of 4U0115+63 (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Widely separated, eccentric pulsating X-ray binaries are shown to be appropriate systems for studying the basic properties of stellar wind accretion. They are free from the complications encountered in closed binaries, where the optical star nearly fills its critical lobe (Avni, 1977). A framework of four observational tests was set up to study the characteristics of wind accretion, and to distinguish between different models of wind acceleration. The tests are applied to the source 4U0115+63, and the accretion process is discussed in both its quiescent states, and during its transient high luminosity outbursts. For the quiescent steady state, two wind profiles, determined from observational data, are compared (Barlow-Lohen, 1977; Castor et al., 1975). The difficulties encountered during the transient high states with respect to the possibility of stellar wind accretion are discussed.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 102; 1, Se; Sept
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 111
    facet.materialart.
    Unknown
    Cosmology (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The current view of the universe is summarized. The equations used to described it and the means of interpreting the diffuse gamma radiation which might result from phenomena which occurred in the distant past are described. The Friedmann model is described in detail.
    Keywords: ASTROPHYSICS
    Type: Gamma Ray Astrophys.; p 187-201
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 112
    facet.materialart.
    Unknown
    Diffuse radiation (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: A diffuse celestial radiation which is isotropic at least on a course scale were measured from the soft X-ray region to about 150 MeV, at which energy the intensity falls below that of the galactic emission for most galactic latitudes. The spectral shape, the intensity, and the established degree of isotropy of this diffuse radiation already place severe constraints on the possible explanations for this radiation. Among the extragalactic theories, the more promising explanations of the isotropic diffuse emission appear to be radiation from exceptional galaxies from matter antimatter annihilation at the boundaries of superclusters of galaxies of matter and antimatter in baryon symmetric big bang models. Other possible sources for extragalactic diffuse gamma radiation are discussed and include normal galaxies, clusters of galaxies, primordial cosmic rays interacting with intergalactic matter, primordial black holes, and cosmic ray leakage from galaxies.
    Keywords: ASTROPHYSICS
    Type: Gamma Ray Astrophys.; p 203-228
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 113
    facet.materialart.
    Unknown
    The interstellar medium and galactic structure (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: High energy gamma rays are produced by the interaction of cosmic rays with the interstellar matter in the galaxy. By combining the gamma ray information with radio data, a picture of the galaxy is presented with regard to the general structure and the effects of cosmic ray pressure. The interaction processes and galactic matter distribution are discussed. Galactic cosmic ray distribution and current gamma ray results are reported.
    Keywords: ASTROPHYSICS
    Type: Gamma Ray Astrophys.; p 99-130
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 114
    facet.materialart.
    Unknown
    Gamma ray astronomy in perspective (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: A brief overview of the development of gamma ray astronomy is presented. Gamma ray telescopes and other optical measuring instruments are highlighted. Emphasis is placed on findings that were unobtainable before gamma ray astronomy. Information on evolution of the solar system, the relationship of the solar system to the galaxy, and the composition of interstellar matter is discussed.
    Keywords: ASTROPHYSICS
    Type: Gamma Ray Astrophys.; p 1-14
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 115
    facet.materialart.
    Unknown
    Relativistic astrophysics - The view from Texas in Baltimore /Review/ (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Recent observational and theoretical work presented at the Tenth Texas Symposium on Relativistic Astrophysics held in Baltimore, Maryland from December 15-19, 1980, is outlined. Areas covered include the theoretical foundations of relativistic astrophysics in general relativity, quantum gravitational theory and the association of grand unification with astronomical and cosmological issues, the cosmic microwave, X-ray, gamma-ray, UV, cosmic ray and gravitational wave backgrounds, the current expansion rate and average mass-energy density of the universe, and mechanisms of galaxy formation. Also discussed are the characteristics of active galaxies and clusters emitting in the gamma-ray and X-ray regions, and compact objects formed from supernova explosions, including pulsars, X-ray-emitting neutron stars, Sco X-1 and SS 433, gamma-ray sources, and X-ray and gamma-ray bursters.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Letters; 22; 1, 19; 1981
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 116
    facet.materialart.
    Unknown
    One millimeter continuum observations of high redshift quasars (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Upper limits to the one-millimeter continuum flux densities of the high redshift quasars B2 1225 + 31, Ton 490, and PHL 957 are presented. The upper limit to the power observed from these quasars at 1 mm is, on the average, one half of the observed power in the continuum at L-alpha. These observations are used to constrain the temperature of a hypothetical dust shell which reddens the quasar line and continuum emission by an extinction optical depth sufficient to account for the anomalously low L-alpha/H-alpha emission line ratio observed in each of these quasars. For the quasars studied, dust shell temperatures between 25 K and 50 to 95 K are prohibited by the present data. A dust shell at a temperature within this span reradiating all the power absorbed from the quasar ultraviolet continuum would produce a one-millimeter flux density greater than the measured upper limit. The average radius of the model dust shell cannot be between 70 kpc and 1 Mpc.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Letters; 22; 1, 19; 1981
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 117
    facet.materialart.
    Unknown
    The interstellar medium and the highly ionized species observed in the spectrum of the nearby white dwarf G191-B2B (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: High-resolution spectra of the nearby (48 pc) white dwarf G191-B2B, obtained with the International Ultraviolet Explorer, reveal sharp resonance lines of N V, C IV, and Si IV. The origin of these features is most likely linked to the white dwarf, possibly being formed in an expanding halo around the star. Interstellar lines of C II, N I, Mg II, Si II, and Fe II are also seen in the spectrum. Analysis of these features indicates an average neutral hydrogen number density of 0.064 for this line of sight. In combination with the recent EUV and soft X-ray results, this is interpreted to mean that the interstellar medium in the most immediate solar vicinity is of the normal density n approximately equal to 0.1/cu cm of lower ionization, while just beyond it, at least in some directions, is a hot lower density plasma. These results are apparently in conflict with the model of the interstellar medium by McKee and Ostriker (1977) in its present form.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 248
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 118
    facet.materialart.
    Unknown
    The 1979-1980 eclipse of Zeta Aurigae. I - The circumstellar envelope (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: A model of the K-star wind far from the K star, and its interaction with the B star, has been derived from a study of Mg(+) and C(+++) resonance lines in the spectrum of Zeta Aurigae during 1979 and 1980. A mass loss rate from the K star of 2 x 10 to the -8th solar masses/year is suggested by the data; the rate of accretion of the K supergiant's material by the B star then being such that the matter accreted over a period of ten years is of the order of the total mass of the photosphere of the B star.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 248
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 119
    facet.materialart.
    Unknown
    The chemical composition, gravity, and temperature of Sirius (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Observational data available for Sirius are of poorer quality than those for Vega, with both the angular diameter and absolute fluxes at different wavelengths being less accurately known. While these data yield an effective temperature of 10,000 + or - 250 K, the 13-color photometry of Johnson and Mitchell (1975) suggests that Sirius is about 450 K hotter than Vega's effective temperature of 9650 + or - 200 K. The c(1) color of the uvby system, the 33-52 and 35-52 colors of the 13-color photometry, and the H-alpha, H-beta and H-gamma line profiles all give log g values of about 4.3, which is in agreement with the value deduced from the mass and the radius, the latter being deduced from the angular diameter and the parallax.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 248
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 120
    facet.materialart.
    Unknown
    The nearby interstellar medium (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The high dispersion spectrometer on board the International Ultraviolet Explorer (IUE) satellite was used to observe interstellar absorption lines in Rasalhague (Alpha Oph). This star is located 18 pc from the sun in the direction of the North Polar Spur, a prominent radio continuum feature in the Ophiuchus region of the sky. The satellite results, combined with previous interstellar line data and observations of the 'local interstellar wind' and soft X-ray emission, support earlier suggestions that the sun is immersed in a supernova remnant which may be an extension of the 'Loop I' or 'North Polar Spur' supernova remnant seen in the Scorpius-Ophiuchus region of the sky.
    Keywords: ASTROPHYSICS
    Type: Nature; 293; Oct. 1
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 121
    facet.materialart.
    Unknown
    Detectors for energies less than 10 MeV (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: In the energy domain 100 keV to 10 MeV, both crystal scintillations and semiconductors are widely used for gamma ray detectors in spectrometer systems. These detectors' operation depend on the fact that gamma rays lose energy by ionization in these materials and electrons and holes are produced. In the case of semiconductors, these electrons and holes are collected by an electric field, and they provide an electric signal that is a direct measure of the energy lost by the gamma ray in the material. Scintillation detectors depend on a further conversion of the energy lost in electron hole pair production to the production of photons. A photomultiplier tube measures the intensity of the photon flux, and an electrical pulse proportional to the photon intensity is produced at the photomultiplier output.
    Keywords: ASTROPHYSICS
    Type: Gamma Ray Astrophys.; p 247-303
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 122
    facet.materialart.
    Unknown
    Gamma ray interaction processes (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Gamma ray detection in the energy region above 1 keV involves measurements of the energy exchange or energy loss between the gamma ray and the mass of the detector. In most cases of interest, it is the kinetic energy imparted to charged particles by the gamma ray which is lost in the detector and measured in order to obtain spectral knowledge between the incident gamma ray photon and the direction of the secondary particles contains important energy information. The interaction gamma ray removal processes in matter are considered. This interaction removal process is characterized by the fact that each gamma ray is removed individually from the incident beam. The number of photons removed in this manner is proportional to the thickness of matter traversed.
    Keywords: ASTROPHYSICS
    Type: Gamma Ray Astrophys.; p 229-246
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 123
    facet.materialart.
    Unknown
    Solar observations (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: High energy processes that take place in the Sun's atmosphere and the relationship of these phenomena to the basic problems of solar activity are discussed. Gamma ray emission exhibits characteristics of the conditions in regions where accelerated high energy particles interact. A number of gamma ray production mechanisms are considered. These include: the Compton effect, magnetobremsstrahlung, pi meson production by proton-proton interaction or by proton-antiproton annihilation, fission and neutral of charged particle radiative capture on inelastic scatter.
    Keywords: ASTROPHYSICS
    Type: Gamma Ray Astrophys.; p 67-94
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 124
    facet.materialart.
    Unknown
    Gamma ray observations of the solar system (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Two general categories are discussed concerning the evolution of the solar system: the dualistic view, the planetesimal approach; and the monistic view, the nebular hypothesis. The major points of each view are given and the models that are developed from these views are described. Possible applications of gamma ray astronomical observations to the question of the dynamic evolution of the solar system are discussed.
    Keywords: ASTROPHYSICS
    Type: Gamma Ray Astrophys.; p 19-24
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 125
    facet.materialart.
    Unknown
    Analysis of observational spectra (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The first step in the analysis of gamma ray energy loss spectra is their conversion to differential energy and differential angular photon spectra. This conversion can be carried out if the detector response and the background are both known. Once these parameters are known, there are many techniques that can be used to convert pulse height spectra to photon spectra. These techniques are discussed and background problems are considered. Emphasis is placed on the analysis of energy loss spectra in the lower gamma ray energy domain. Problems of transportations from pulse height to photon space are most complex in this domain and the methods shown illustrate many of the problems which arise in the general analysis of energy loss spectra.
    Keywords: ASTROPHYSICS
    Type: Gamma Ray Astrophys.; p 337-382
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 126
    facet.materialart.
    Unknown
    Detectors for energies greater than 10 MeV (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The detector telescopes used in gamma ray astronomy in general are more similar to particle detectors than to optical devices, since the high frequency of the radiation precludes the use of reflection or diffraction techniques, but the high energy content of each photon does enable them to be detected with scintillators, track imaging chambers, and solid state detectors. Within the gamma ray range, the basic design of the instrument changes as the energy of the gamma ray exceeds 10 to 20 MeV, and therefore, moves from the region where the Compton effect predominates in the absorption of the gamma ray to that where electron pair production is most important. In the energy range from 10 to 20 MeV to several times 10,000 MeV, gamma ray telescopes are usually built so that the electron pair may be seen and the properties of the electrons measured.
    Keywords: ASTROPHYSICS
    Type: Gamma Ray Astrophys.; p 305-336
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 127
    facet.materialart.
    Unknown
    Galaxies (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Normal galaxies, radio galaxies, and Seyfert galaxies are considered. The large magellanic cloud and the great galaxy in Andromedia are highlighted. Quasars and BL lacertae objects are also discussed and a review of the spectral observations of all of these galaxies and celestial objects is presented.
    Keywords: ASTROPHYSICS
    Type: Gamma Ray Astrophys.; p 165-185
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 128
    facet.materialart.
    Unknown
    Rotation of dwarf star chromospheres in the ultraviolet (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Periodic variations in the ultraviolet fluxes of chromospheric emission line multiplets are investigated for F, G and K stars as evidence of rotational modulation. Vacuum ultraviolet spectra were obtained with the IUE spacecraft for six stars as many as 11 times over the period April 23 to December 3, 1980. Variations in the emission fluxes of the hydrogen Lyman-alpha, Si II and Mg II lines are observed with periods up to 47 days. The periodicity, which is identified with rotational modulation, is found to persist over many rotational cycles, although the periods and time dependences of the fluxes from the different ionic species are not identical, probably due to differential rotation and global distributions. The spread of the UV periods is observed to be within 10%, with one or two peaks per cycle and a ratio of modulated to umodulated flux ranging from 1.1 to 3.0, analogous to solar behavior.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 248
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 129
    facet.materialart.
    Unknown
    Scale covariant gravitation. V - Kinetic theory. VI - Stellar structure and evolution (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: A scale covariant kinetic theory for particles and photons is developed. The mathematical framework of the theory is given by the tangent bundle of a Weyl manifold. The Liouville equation is derived, and solutions to corresponding equilibrium distributions are presented and shown to yield thermodynamic results identical to the ones obtained previously. The scale covariant theory is then used to derive results of interest to stellar structure and evolution. A radiative transfer equation is derived that can be used to study stellar evolution with a variable gravitational constant. In addition, it is shown that the sun's absolute luminosity scales as L approximately equal to GM/kappa, where kappa is the stellar opacity. Finally, a formula is derived for the age of globular clusters as a function of the gravitational constant using a previously derived expression for the absolute luminosity.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 248
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 130
    facet.materialart.
    Unknown
    A search for neutral hydrogen in D and cD galaxies (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Recent X-ray spectroscopic results suggest that 2-3 solar masses/yr of cooling gas may be falling into M87 and as much as 300 solar masses/yr into giant galaxies in rich clusters. The eventual fate of the gas in the radiatively accreting flow is an open question. In an attempt to set some bounds on the evolution of the gas, a sensitive search was performed for H I in a sample of eight D and cD galaxies in rich and poor clusters. Null detections in all cases set upper limits of (4-20) x 10 to the 8th solar masses of H I in the giant galaxies. Possible reasons for these nondetections and alternative evolutionary fates for the accreting gas are discussed.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal; 86; Aug. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 131
    facet.materialart.
    Unknown
    Gamma ray bursts - A review of recent high-precision measurements (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: (Previously announced in STAR as N81-30077)
    Keywords: ASTROPHYSICS
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 132
    facet.materialart.
    Unknown
    The X-ray structure of a galaxy cluster at z = 0.54 - Implications for cluster evolution and cosmology (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: High-resolution X-ray observations of the rich cluster 0016+16 at a redshift of 0.541 are presented. The emitting gas in this cluster is hot and extremely luminous, and its structure resembles that seen in the brightest nearby cluster sources. In most of its properties, 0016+16 resembles a richer version of the Coma cluster, and it offers little support to the hypothesis that clusters at z greater than 0.5 differ fundamentally from nearer objects.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 251
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 133
    facet.materialart.
    Unknown
    Statistical equilibrium in cometary C2. III - Triplet-singlet, Phillips, Ballik-Ramsay, and Mulliken bands (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: A new series of vibrational bands is predicted which arises from transitions between the lowest electron states of the triplet and singlet states of homonuclear C2. The predictions are useful for C2 identifications and for disentangling congested low resolution spectra that characterize new observations. Predictions are also made for Mulliken, Phillips, and Ballik-Ramsay band sequences, and all calculations are made with the assumed molecular constants and computational methods of KSO-II.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 251
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 134
    facet.materialart.
    Unknown
    Orbital stability constraints on the nature of planetary systems (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: A fully self-consistent, N-body computer code is used to study conditions under which model planetary systems, each consisting of a star and two 'planetary' companions, become orbitally unstable as a result of gravitational interactions between the companions. A formula describing a necessary condition for orbital stability is given. It is found that giant gaseous protoplanets of the type postulated by Cameron (1978) to be precursors of the present-day solar system planets could have stable orbits for at least 10,000 years, the time required for significant core formation in a typical giant gaseous protoplanet.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 251
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 135
    facet.materialart.
    Unknown
    Model for the circumstellar gas around alpha Orionis (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Models are presented to explain the physical conditions in the circumstellar envelope surrounding the red supergiant Alpha Orionis. The models of the CO density and neutral atomic potassium density are calculated for the outer shell to reproduce simultaneously both the radio detection of CO and optical measurements of the amount of scattering by neutral potassium around Alpha Ori. CO and potassium loss rates of 7 x 10 to the 39th/sec and 8 x 10 to the 37th/sec are obtained, which imply a potassium to carbon ratio greater than that of the sun by about a factor of 25. The low carbon abundance may be attributed to extensive CNO processing, and, together with the potassium abundance, indicates a total mass loss rate of 0.000015 solar masses/year. The mass loss, mass and abundance properties of Alpha Ori suggest it to be the progenitor of a Type II supernova such as Cas A.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 251
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 136
    facet.materialart.
    Unknown
    On the variation of G and scale invariant gravitation - A reply (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: In 1977 Canuto et al. proposed a formalism to deal with the possible difference between gravitational and atomic clocks (or times). The formalism was incomplete since the authors only dealt with the gravitational Lagrangian LG, leaving the specific form of the matter Lagrangian Lm for a later study. Kembhavi and Pollock (1981) have proposed a matter Lagrangian which they define as 'the only possible one' or 'the inescapable form of Lm'. Adding this Lm to Lg, they claim that the theory does not allow for a variable G. The present paper gives a mathematical proof that the proposed matter Lagrangian, far from being 'the only one' or 'the inescapable form', is actually a very special case which already contains imprinted all the conclusions Kembhavi and Pollock claim to have discovered. Their results are therefore erroneous.
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society; vol. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 137
    facet.materialart.
    Unknown
    The resonance line of B II in IUE spectra of chemically peculiar stars (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: A description is presented of high-dispersion spectroscopic observations of eight chemically peculiar stars including Kappa Cnc and Mu Lep, and of one normal comparison star, Nu Cap, in the vicinity of 1362 A. The reported data were obtained with the International Ultraviolet Explorer during the first 15 months of its operation. The initial reduction of the data, which were originally described in a qualitative summary by Leckrone (1980), was affected by a serious error in the calibration of the instrument's intensity transfer function. This error has been corrected in the currently presented data. The results of spectrum syntheses of the 1362 A feature are also described for several of the stars.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 250
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 138
    facet.materialart.
    Unknown
    New observational constraints on the M87 jet (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: New observations at 1.6-3.45 microns confirm the presence of a dramatic (change in spectral index of approximately 1) break between radio-IR wavelengths and 6,000 A in the spectrum of the M87 jet. These data, in combination with data taken in other spectral regions, show that the individual knots in the M87 jet have nearly the same spectral indices and nearly the same large (change in spectral index of approximately 1) spectral break. This large spectral break and the constancy of spectral properties between the knots pose serious constraints for models of the M87 jet.
    Keywords: ASTROPHYSICS
    Type: Nature; 294; Nov. 26
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 139
    facet.materialart.
    Unknown
    The high energy X-ray spectrum of 4U 0900-40 observed from OSO 8 (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The X-ray source 4U 0900-40 (= Vela XR-1) was observed with the high-energy X-ray spectrometer on OSO 8 for one week in 1976 and three weeks in 1978. Spectra of the source are presented above 16 keV. No systematic difference exists between the X-ray eclipse centers and the eclipse centers predicted from optical ephermerides. Short period intrinsic variability in the system's X-ray intensity may be related to changes in the Compton scattering optical depth in the system and does not require sporadic mass transfer via Roche lobe overflow. The 282 s modulation in the source's X-ray flux above 21 keV consists of two essentially similar pulses per period, most easily interpreted as arising from the two different magnetic poles of a rotating neutron star. The secondary appears to be a spherically accreting, magnetic neutron star.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 250
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 140
    facet.materialart.
    Unknown
    The visual surface brightness relation and the absolute magnitudes of RR Lyrae stars. I - Theory (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: A theoretical relation analogous to the Barnes-Evans relation between stellar surface brightness and V-R color is derived which is applicable to the temperatures and gravities appropriate to RR Lyrae stars. Values of the visual surface brightness and V-R colors are calculated for model stellar atmospheres with effective temperatures between 6000 and 8000 K, log surface gravities from 2.2 to 3.5, and A/H anbundance ratios from -0.5 to -3.0. The resulting relation is found to be in reasonable agreement with the empirical relation of Barnes, Evans and Moffet (1978), with, however, small sensitivities to gravity and metal abundance. The relation may be used to derive stellar angular diameters from (V,R) photometry and to derive radii, distances, and absolute magnitudes for variable stars when combined with a radial velocity curve. The accuracies of the radii and distances (within 10%) and absolute magnitudes (within 0.25 magnitudes) compare favorably with those of the Baade-Wesselink method currently in use.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 250
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 141
    facet.materialart.
    Unknown
    Matter-antimatter separation in the early universe by rotating black holes (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Consideration of the effect of rotating black holes evaporating early in the universe shows that they would have produced oppositely directed neutrino and antineutrino currents, which push matter and antimatter apart. This separation mechanism is, however, too feeble to account for a present baryon-to-photon ratio of 10 to the -9th, and has no significant observational consequences.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 249
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 142
    facet.materialart.
    Unknown
    Effect of long-term intensity variations on pulsar searches and the pulsar luminosity function (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Long-term intensity data for five pulsars are used to obtain the probability density distribution of intensities for each pulsar, and it is found that they are described satisfactorily by chi-squared distributions. Based on these distributions, the number of new pulsars expected to be found on repeatedly searching the same region of the sky with the same sensitivity is given. Nearly 25 percent more new pulsars are expected to be found on the first repeat search. It is also shown that the luminosity function deduced from either a single survey or surveys with very different sensitivities is not affected by the omission of flux density variations in the calculation of selection effects. Finally, a method is proposed for deriving the luminosity function by combining the different searches of a given area on the basis of a probabilistic approach to the evaluation of selection effects.
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society; vol. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 143
    facet.materialart.
    Unknown
    Annihilation radiation from a hot e/+/-e/-/ plasma (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The radiation from electron-positron annihilations in a plasma of temperature above 10 to the 8th K is investigated as a possible source of the emission line at energies between 400 and 460 keV frequently seen in gamma-ray bursts. The annihilation rate and luminosity of an optically thin electron-positron plasma and the energy distribution of the resulting annihilation radiation are calculated by the use of a Monte Carlo technique as functions of temperature. Results indicate the annihilation spectrum to be peaked at an energy of 0.511 MeV plus a temperature-dependent blueshift, and the annihilation line to be significantly temperature-broadened. The widths of the observed burst emission lines set an upper limit of 3 x 10 to the 8th K on the temperature of any pair annihilation region in burst sources, which is considerably lower than the typical kinetic temperatures of the radiating particles. It is thus inferred that either the annihilation region is nonthermal, or spatially distinct from the burst site.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 250
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 144
    facet.materialart.
    Unknown
    4-8 micron spectrophotometry of OH 0739-14 (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Spectrophotometry of the dust-embedded late-type star OH 0739-14 shows an absorption feature at 6.0 microns characteristic of H2O ice at temperatures significantly lower than 150 K, confirming the identification of H2O ice in the circumstellar shell in this source. The differences in the infrared spectra of HO 0739-14 and embedded molecular cloud sources are attributed to the different cloud lifetimes and temperature regimes in which the molecules are formed. A lower limit to the mass loss rate of 0.0001 solar mass per year is derived, based on the column density of ice and the size and the expansion velocity of the circumstellar cloud.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 250
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 145
    facet.materialart.
    Unknown
    The circumstellar envelopes of F- and G-type supergiants in the Large Magellanic Cloud (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The outer atmospheres of four F- and G-type supergiants in the LMC are compared with those of their Milky Way counterparts by means of 2.5 and 5.1 A/mm high dispersion Echelle spectra. Na I D line doubling indicates extensive circumstellar envelopes, mass loss rates greater than 0.00001 solar masses/year, and outflow velocities of 10-60 km/sec. The Ca II H and K lines yield new data on extragalactic star chromospheres.
    Keywords: ASTROPHYSICS
    Type: (ISSN 0185-1101)
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 146
    facet.materialart.
    Unknown
    Low-frequency radio observations of poor clusters of galaxies (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Observations have been made at the Clark Lake Radio Observatory of 16 poor clusters of galaxies at 34.3 MHz. Four of the poor clusters were detected at flux densities greater than 20 Jy. The spectra of the four detected clusters are all rather steep. Two of the detected clusters, AWM 4 and AWM 5, are also known to be X-ray sources. The possibility that the X-ray-emitting gas is heated by Coulomb interactions with the relativistic electrons responsible for the radio emission is investigated, and it is found that the observed X-ray luminosities can be accounted for if the electron energy spectrum extends to very low energies (gamma approximately 1-10). Collective plasma effects may increase the heating efficiency and eliminate the need to extrapolate the electron energy spectrum to such low values.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal; 86; June 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 147
    facet.materialart.
    Unknown
    The abundance and excitation of the carbon chains in interstellar molecular clouds (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Emission lines from the carbon chains HC3N, HC5N, HC7N and HC9N were observed at 3 mm, 7 mm, and 1.4 cm in a number of dark clouds, Orion A and IRC(plus)10216. Non-LTE models were constructed to describe excitation and column densities. Component models for the Taurus dark cloud TMC-1 suggested that relative molecular abundances do not vary substantially along the cloud ridge, whereas the H2 density does by a factor of three. Data available for other dark clouds showed that the decrease in abundance with length from one carbon chain to the next is nearly constant, being close to 2.3. The decline in carbon chain abundance with length is steeper in Orion KL than in dark clouds by a factor of approximately four. Abundance ratios derived for the carbon star IRC(plus)10216 are uncertain, due to difficulties in modeling excitation rates in this environment.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 99; 2, Ju; June 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 148
    facet.materialart.
    Unknown
    Interstellar extinction by small-coated or uncoated graphite grains (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Calculations have been made on the theoretical extinction of spherical graphite particles from 130 to 3500 nm. It is found that graphite particles of radius near 20 nm can have small (0.5 nm) coatings and still be responsible for the 220 nm peak in the interstellar extinction curve. New calculations also show that the effect of finite particle size is relatively unimportant in determining the extinction of graphite spheres at 220 nm.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 246
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 149
    facet.materialart.
    Unknown
    Molecular hydrogen ion /H2+/ absorption in planetary nebulae (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Several IUE spectra of planetary nebulae show an absorption feature shortward of 1500 A which is believed to be due to H2(+). The nebulae are excited by stars of spectral type O3-O7 or continuum, and all but one have double-shell structure.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal; 86; June 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 150
    facet.materialart.
    Unknown
    Interplanetary Alfvenic fluctuations - A stochastic model (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The concept of minimum variance is investigated for nonplanar interplanetary Alfvenic fluctuations in which the field direction varies randomly. The theory of the random wandering of a vector of constant length is developed as a representation of the magnetic field, and it is found that the minimum variance tends to coincide with the mean field directions over the correlation time of the fluctuations. The Fokker-Planck limit of the theory is then developed and used to analyze the statistic distribution of field directions with and without a reflecting barrier. Results suggest that the tendency of the Alfvenic fluctuations to have a direction of minimum variance statistically aligned with the mean magnetic field may be purely a consequence of the randomness of the fluctuation and not imply that the fluctuations are necessarily plane waves. Extensive statistical studies of the observed directional variations of the interplanetary magnetic field are necessary to test this hypothesis.
    Keywords: ASTROPHYSICS
    Type: Journal of Geophysical Research; 86; Sept. 1
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 151
    facet.materialart.
    Unknown
    Numerical three dimensional calculations of tidally induced binary protostar formation (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The manner in which interstellar clouds fragment into subcondensations capable of becoming stars is still unknown. A variety of mechanisms may be responsible for cloud fragmentation. The considered investigation is concerned with a mechanism which is based on tidal forces due to a companion cloud. A 3D code is used to study the tidal effects of point sources of various masses located in the equatorial plane of an initially uniform density, uniformly rotating, isothermal gas cloud. It is found that tidal forces can be quite effective at inducing fragmentation in an initially uniform cloud, although the effects are most pronounced for low thermal energy clouds, perturbed by perhaps unreasonably large tidal forces. It is also seen that tidal forces may be much less efficient at preventing the collapse of a cloud than has previously been supposed.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 246
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 152
    facet.materialart.
    Unknown
    Semi-empirical estimates of gravitational wave generation by stellar collapse (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The problems of the generation and detection of gravitational waves and the difficulty of detecting the burst of gravitational radiation produced by a stellar collapse in our Galaxy, or in neighbouring clusters of galaxies where such collapses are expected to occur frequently, have been reviewed elsewhere. As stellar collapses, explosions, or supernovae are poorly understood, the values of the strength of these sources depend on uncertain assumptions. However, it is possible to make some independent estimates on semi-empirical grounds, using observed facts concerning the remnants of stellar evolution. These estimates, reported here, have serious weaknesses. They must involve oversimplified models and very crude standard calculations of the collapse and radiation processes. Also, because they are based on observed properties of stellar remnants, they say nothing about collapses which do not produce observable remnants. Although this selection may introduce a strong bias, these estimates deserve consideration because they are tied to real data.
    Keywords: ASTROPHYSICS
    Type: Nature; 283; Feb. 7
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 153
    facet.materialart.
    Unknown
    Galaxies and far-infrared emission (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The far-infrared luminosities of the central few hundred parsecs of many galaxies may exceed by more than an order of magnitude the amount expected from late-type stars. However, for the M82, NGC 253, NGC 1068 and several other galaxies studied in the present paper, the inferred mass-to-luminosity ratios are within the limits expected for stellar distributions containing early-type stars.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 235
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 154
    facet.materialart.
    Unknown
    Relativistic jets and the continuum emission in QSOs (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The radio through optical, and possibly X-ray, emission of QSOs and active galactic nuclei is analytically interpreted in terms of a relativistic jet containing high-energy particles and a magnetic field. Parallel to the jet axis, a strong, compact radio source and strongly polarized radiation are detected, while larger viewing angles relative to the jet axis result in spectral dominance by the central region containing the 'energy machine' which drives the energy flux in the jet. It is shown that the relativistic jet model can explain the association of OVVs with strong, variable radio sources, strong optical polarization, and continuity of the radio to optical spectra.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 235
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 155
    facet.materialart.
    Unknown
    HEAO 1 spectra of X-ray emitting Seyfert 1 galaxies (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The paper presents the 2-50-keV X-ray spectra and time variability information on seven Seyfert 1 galaxies NGC 3783, NGC 4151, NGC 5548, NGC 6814, MK 509, MCG 8-11-11, and ESO 141-G55, obtained with the A2(2) experiment on HEAO 1. It is concluded that the spectra of Seyfert 1 galaxies can be well represented by flat power laws of high-temperature thermal breamsstrahlung models with relatively low column densities.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 235
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 156
    facet.materialart.
    Unknown
    X-ray line emission from the Tycho supernova remnant (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The A-2 experiment onboard HEAO 1 has observed the X-ray spectrum of the Tycho supernova remnant in the energy range 0.5-20 keV. The spectrum reveals four significant line features: the K(alpha) lines of silicon, sulfur, and iron; and the L lines of iron. Comparisons between the silicon and sulfur equivalent widths and K(alpha) iron line energies of Tycho and Cas A suggest that the X-ray emitting plasma in Tycho is further from collisional ionization equilibrium than that in Cas A.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 235
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 157
    facet.materialart.
    Unknown
    Asymptotic freedom in the early big bang and the isotropy of the cosmic microwave background (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: It is suggested that a superunified field theory incorporating gravity and possessing asymptotic freedom could provide a solution to the problem of the isotropy of the universal 3 K background radiation. Thermal equilibrium could be established in this context through interactions occurring in a temporally indefinite pre-Planckian era.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 235
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 158
    facet.materialart.
    Unknown
    Elemental abundances in a Type I supernova remnant (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The solid-state spectrometer (SSS) on the HEAO 2 (Einstein) X-ray observatory observed the X-ray spectrum of Tycho's SNR. The observations show a relative excess of line emission from Si, S, and Ar by not less than 6 compared to that expected from a plasma of solar composition in collisional equilibrium and by a factor of not less than 3 compared to Cas A. Similar excesses are not found for line emission from Mg and Fe. The data suggest that the SN observed by Tycho in 1572 produced significant amounts of Si group elements but did not eject large amounts of Fe as predicted by some models of Type I SN events.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 235
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 159
    facet.materialart.
    Unknown
    Comparison of predicted and observed spectral energy distribution of K and M stars. I - Alpha Bootis (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The K2 IIIp star Alpha Bootis has been observed from the ground at 0.536 to 1.070 microns, and from an airplane at 1.21 to 3.90 microns. In the present paper, an absolute flux curve, constructed from these observations with an overall precision greater than + or - 2% in F-lambda, is compared with previous photometry and spectrometry.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 235
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 160
    facet.materialart.
    Unknown
    Origin of large interstellar grains toward Rho Ophiuchi (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The paper considers why the interstellar grains toward Rho Oph are unusually large. Because the visual opacity per gram is lower than average toward Rho Oph, it is concluded that the simplest interpretation of the observations is that grain coagulation has occurred. This result may be important for understanding the evolution of interstellar clouds and may provide insight into the initial stages of the formation of large solid bodies such as planets.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 235
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 161
    facet.materialart.
    Unknown
    150 GHz observations of three radio galaxies (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Radio galaxies were observed for the first time at 150 GHz. The central sources in Cyg A and 3C 111 were detected, as were the two radio lobes of Cyg A. No emission was found from the central source in 3C 236. The millimeter-wavelength emission from the central sources in Cyg A and 3C 111 is probably due in each case to a compact component that is optically thin to synchrotron radiation above about 35 GHz. These components are similar, although the compact component in 3C 111 is more luminous at both radio and X-ray wavelengths than the one in Cyg A. The 3C 111 central source was much weaker than anticipated on the basis of prior observations at 90 GHz, perhaps due to variability. Even at 150 GHz, there is no evidence of a high-frequency cutoff in the spectrum of the central source in Cyg A, and variability of this source also is expected. The flux densities of the Cyg A lobes are consistent with the power laws derived at lower frequencies, indicating that no steepening occurs in their spectra out to at least 150 GHz. There is no evidence for a compact, optically thick component in 3C 236.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 235
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 162
    facet.materialart.
    Unknown
    On the enhancement of the IMF magnitude during 1978-1979 (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The magnitude of the interplanetary magnetic field (IMF) exhibits an enhancement during 1978-1979 relative to all years back to 1963. It is shown that IMF magnitude variations over the 1966-1979 period represent the combined effect of variations in both the radial flux density of the IMF and the degree of spiraling of the IMF, consistent with the theoretical model of Parker. The 1978-1979 IMF magnitude enhancement is due to an enhancement of radial flux which was in turn related to an increase of magnetic flux leaving solar active regions. It is also shown that during the corotating stream dominated years 1973-1976, the IMF was less wound up than it was during other years, and that 1973-1974 were years of enhanced radial flux.
    Keywords: ASTROPHYSICS
    Type: Journal of Geophysical Research; 86; June 1
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 163
    facet.materialart.
    Unknown
    1548C27 - An interesting new cometary nebula (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The object 1548C27, a faint cometary nebula of classical form, discovered by an examination of early Near Infrared Photographic Sky Survey (NIPSS) data (1979) is presented. Direct imaging and polarimetric, photometric, and spectroscopic observations are reported. Early survey test photographs show that the object lies at R.A. 19h40m48s, Decl. +23 deg 17 arcmin 09 arc sec (1950) in the Vulpecula constellation in the immediate vicinity of the complex H II region and galactic cluster NGC 6820/6823. From the photographs, the nebula was estimated to be 15 m visual and of color class one. The object was observed spectroscopically in the region 5700-6800 A using an Image Dissector Scanner with a 1.8 m reflector, and the spectral scan, obtained on November 4, 1978, is presented. New information on cometary nebulae may further illuminate the evolutionary importance of the objects.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal; 86; May 1981
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 164
    facet.materialart.
    Unknown
    VLBI observations of the nucleus of the radio galaxy Cygnus A (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The central component of the radio galaxy Cygnus A has been observed in several (very long baseline interferometry) experiments between 1975 and 1979, and the results have been combined to derive a model for the brightness distribution. Some 65% of the nuclear emission appears to come from a compact core. The remaining flux density comes from a more extended region (or regions) up to 4 or 5 mas away lying along a position angle near 100 deg, which is close to that of the extended lobes. Evidence that compact central components reflect the collimation and transport of energy to the outer lobes of radio galaxies is discussed, and several interpretations of the observed asymmetries are considered.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 97; 1, Ap; Apr. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 165
    facet.materialart.
    Unknown
    Globular cluster winds with central accretion by a massive compact object or subcluster (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Steady-state isothermal wind flows are computed with accretion by a central mass concentration in spherically symmetric systems of gas-losing stars. Solutions are uniquely determined by two dimensionless parameters lambda and m, where lambda is approximately equal to the square of the ratio of the central escape velocity to the sound speed and m is approximately equal to the ratio of the central point mass to the cluster core mass. The models are applied to globular clusters for two types of central mass concentration - a single massive black hole and a subcluster of massive stars. A hard (greater than a keV) X-ray source due to a central black hole fed by clusterwide inflow does not provide a consistent model for globular cluster X-ray sources. However, in the case of hot (T being greater than or approximately equal to 2 x 10 to the 5th K) winds, gas trapping by a central subcluster of neutron stars or of binaries containing white dwarfs could explain recent UV and H-alpha observations. Similar applications to elliptical galaxies are discussed.
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society; vol. 195
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 166
    facet.materialart.
    Unknown
    Production spectrum of gamma rays in interstellar space through neutral pion decay (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: A simple representation is obtained of the observed invariant cross section for the production of neutral pions in proton-proton collisions. Using this representation, the differential and integral production spectra of gamma rays in the galaxy are calculated from interactions of cosmic ray nuclei with interstellar gas. It is shown that the uncertainties in deducing interstellar proton spectrum by demodulating the observed spectrum have only a limited effect on the gamma ray spectrum. Also determined is the gamma ray production spectrum through bremsstrahlung process for a typical interstellar electron spectrum derived from the radio spectrum in the galaxy.
    Keywords: ASTROPHYSICS
    Type: Astrophysics and Space Science; 76; 1, Ma; May 1981
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 167
    facet.materialart.
    Unknown
    Type II Cepheids - A comparison of theory with observations (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 244
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 168
    facet.materialart.
    Unknown
    On the fragmentation of rotating interstellar clouds (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Simple physical arguments are used to estimate the time scale for fragmentation of a collapsing, rotating, isothermal, interstellar cloud. This time scale is compared with a similarly estimated time scale for the collapse upon itself of a transitory ring structure. It is shown to be plausible for a cloud with a given ratio of rotational to gravitational energy (beta) that as the ratio of thermal to gravitational energy (alpha) is varied, there is an intermediate range of alpha where a ring forms and collapses on itself, prior to fragmentation. For higher or lower alpha, however, the cloud fragments prior to ring self-collapse. The analysis is compared with the results of numerical multidimensional, gravitational, hydrodynamical collapse and shown to be in good agreement with them.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 244
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 169
    facet.materialart.
    Unknown
    Radio emission in the directions of cD and related galaxies in poor clusters. III - VLA observations at 20 cm (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: VLA radio maps and optical identifications of a sample of sources in the directions of 21 Yerkes poor cluster fields are presented. The majority of the cluster radio sources are associated with the dominant D or cD galaxies (approximately 70 percent). Our analysis of dominant galaxies in rich and poor clusters indicates that these giant galaxies are much more often radio emitters (approximately 25 percent of cD's are radio active in the poor clusters), have steeper radio spectra, and have simpler radio morphologies (i.e., double or other linear structure) than other less bright ellipticals. A strong continuum of radio properties in cD galaxies is seen from rich to poor clusters. It is speculated that the location of these dominant galaxies at the cluster centers (i.e., at the bottom of a deep, isolated gravitational potential well) is the crucial factor in explaining their multifrequency activity. Galaxy cannibalism and gas infall models as fueling mechanisms for the observed radio and X-ray emission are discussed
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal; 86; Jan. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 170
    facet.materialart.
    Unknown
    Magnetohydrodynamic perturbations of Robertson-Walker universes and of anisotropic Bianchi type-I universes (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Magnetohydrodynamic (MHD) perturbations in flat Robertson-Walker universes were analyzed, emphasizing their effects on galaxy formation. The Newtonian approximation is used. There is no increase in the growth rates beyond those of the usual perturbed Robertson-Walker models; the MHD modes extract as much energy as they contribute. Some global properties of fully MHD Bianchi I relativistic models are analyzed including vorticity, fluid accelerations, and dissipative effects. The time dependence of perturbations of a fully MHD diagonal Bianchi I cosmology is studied, with an enhanced growth rate of the density contrast of t found which is still not exponential Jeans-type growth. This indicates that a more detailed analysis is needed if a solution to the galaxy formation problem in MHD cosmologies is to be found.
    Keywords: ASTROPHYSICS
    Type: Nuovo Cimento B; vol. 60B
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 171
    facet.materialart.
    Unknown
    Spectral evolution of the 5 March 1979 gamma burst (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The spectral development of the intense gamma-ray burst observed on March 5, 1979 by nine spacecraft spaced on an interplanetary scale is discussed. As observed by the Pioneer Venus Orbiter detector, the hardness ratio of the burst, defined as the ratio between counts in the 100-1000 keV channels to those in the 50-100 keV channel, decreases during the very fast rise and subsequent 75 msec of the burst, consistent with a decrease in black-body temperature from 30 to 26 keV, and then increases during the shoulder on the gamma-ray burst light curve. Following the burst, the source was observed to exhibit many of the characteristics of a hard X-ray pulsar with a period of 8.0 sec and a hardness ratio varying in phase with the intensity. The observed characteristics of the pulsations are interpreted in terms of hot spots at the magnetic poles of a rotating neutron star, although it is shown that the simple cooling of residual hot spots does not completely explain the pulsations. Alternative explanations for the pulsation include accretion or an effect of beam geometry.
    Keywords: ASTROPHYSICS
    Type: Nature; 289; Jan. 8
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 172
    facet.materialart.
    Unknown
    Dynamics of the universe and spontaneous symmetry breaking (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: It is shown that the presence of a phase transition early in the history of the universe, associated with spontaneous symmetry breaking (believed to take place at very high temperatures at which the various fundamental interactions unify), significantly modifies its dynamics and evolution. This is due to the energy 'pumping' during the phase transition from the vacuum to the substance, rather than the gravitating effects of the vacuum. The expansion law of the universe then differs substantially from the relation considered so far for the very early time expansion. In particular it is shown that under certain conditions this expansion law is exponential. It is further argued that under reasonable assumptions for the mass of the associated Higgs boson this expansion stage could last long enough to potentially account for the observed isotropy of the universe.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 241
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 173
    facet.materialart.
    Unknown
    Interplanetary gas. XXV - A solar wind and interplanetary magnetic field interpretation of cometary light outbursts (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Possible relationships of cometary brightness outbursts with the solar wind and interplanetary magnetic field are examined. Two types of outburst are distinguished: those which involve a significant brightening of both the head and the tail in a comet with a conspicuous plasma tail (Class I), and those involving the brightening of the central condensation of a previously faint comet with no detectable plasma tail (Class II). Class I bursts, as exemplified by Comet Morehouse 1908c, are attributed to the generation in the head of enhanced amounts of ions and their injection into the tail shortly before it disconnects, with ionization provided by sector boundary crossings. Class II events, as exhibited by Comet P/Tuttle-Giacobini-Kresak 1973b, are interpreted as the result of the bombardment of the nucleus by disturbed solar wind near corotated high-speed streams and sector boundaries, leading to highly exothermic chemical reactions.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 241
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 174
    facet.materialart.
    Unknown
    Electron densities for six planetary nebulae and HM Sagittae derived from the semiforbidden C III lambda 1907/1909 ratio (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 241
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 175
    facet.materialart.
    Unknown
    IUE observations of a luminous M supergiant that exhibits emission continuum in the far ultraviolet (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: IUE observations of the late-type M supergiant star TV Gem which reveal an intense continuum in the far ultraviolet are discussed. TV Gem was observed in low dispersion in November 1979 and in high and low dispersion in January 1980 by the short and long wavelength cameras of the IUE spectrometer. An essentially featureless UV continuum was obtained, with the exception of a number of broad absorption features in the short wavelength region. A comparison with ground-based observations indicates that at wavelengths greater than 3200 A the continuum emission is essentially due to the M1 supergiant, while at shorter wavelengths the continuum is dominated by a hot companion. The UV continuum can be explained by a B9 or A1 III-IV early companion approximately 2 to 3 magnitudes fainter than the M1 supergiant, or by an accretion disk formed by mass transfer from the extended envelope of the M1 primary onto the surface of a highly condensed secondary. Soft X-ray observations from HEAO 2 are suggested as a means to investigate these interpretations.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 241
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 176
    facet.materialart.
    Unknown
    B2 1141 + 37 - A giant radio galaxy with remarkable radio and optical properties (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Observations of the giant radio galaxy B2 1141+37, which has a widely separated two-component radio structure and is optically identified with a tight chain of galaxies, are reported. The source was observed at 4900 MHz with the VLA at an effective integration time of 17 min. The map obtained shows two radio lobes with maxima coinciding with those in a previous 1415 MHz map and intensities about 1.5 times smaller than those obtained by extrapolating the spectrum defined by the flux density at 408 and 1415 MHz. Measurements of the redshifts of the two brightest galaxies identified with the radio source with an image intensified dissector scanner result in values of 0.1145 and 0.1155, which imply, with a Hubble constant of 50 km/sec per Mpc, a distance of 687 Mpc to the radio source and a separation of 1.0 Mpc between the lobes making it one of the largest radio sources known.
    Keywords: ASTROPHYSICS
    Type: Nature; 288; Dec. 4
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 177
    facet.materialart.
    Unknown
    A very rapid turning of the plasma-tail axis of comet Bradfield 19791 on 1980 February 6 (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Schmidt camera photographs of comet Bradfield 19791 obtained at the Joint Observatory for Cometary Research (JOCR) indicate that a rapid change took place in the comet's plasma tail on 1980 February 6. On that date, a sequence of photographs spanning 27.5 minutes shows a 10 deg shift occurring in the plasma-tail axis between the first and last exposures. The speed of this tail-turning event greatly exceeds that of any other known event and even exceeds turning rates for individual tail streamers. An interpretation based on the windsock theory of plasma tails is that the comet entered a region of rapidly changing solar-wind flow direction. While the search for an associated solar-wind event from near-earth spacecraft observations is a future activity, the present analysis shows that a 50 km/s change in the polar component of the solar-wind velocity, from about 30 km/s northward to about 20 km/s southward, would have produced the 10 deg shift in the tail axis.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 241
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 178
    facet.materialart.
    Unknown
    X-ray spectral constraints on the broad-line cloud geometry of NGC 4151 (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: X-ray spectral data from NGC 4151 taken with the Einstein Solid-State Spectrometer (SSS) and the HEAO 1 A-2 experiment cannot be simply reconciled with absorption from a uniform column of cold gas. The SSS data can, however, be explained in terms of a clumped absorber with approximately 10% uncovered fraction and factor-of-two overabundances in Z equal to or greater than 14 elements relative to solar oxygen. It is shown that these and previously reported spectral and variability data can be quantitatively reconciled with absorption arising in the cold clouds responsible for the broad optical line emission if the cloud dimensions are small compared to the central source size. It is suggested that the lack of significant X-ray absorption observed from much higher luminosity Seyferts and quasars is a natural consequence of the proposed picture for NGC 4151.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 241
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 179
    facet.materialart.
    Unknown
    A search for interstellar pyrrole - Evidence that rings are less abundant than chains (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Searches for three transitions of pyrrole (C4H5N) give maximum column density = 3-10 x 10 to the 13th per sq cm in Sgr B2. This limit is more than 10 times lower than previous ring molecule limits, and is slightly lower than column densities of known interstellar molecules with from four to six heavy atoms.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 241
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 180
    facet.materialart.
    Unknown
    Circular polarization from scattering by circumstellar grains (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: It is suggested that observations of circular polarization can be a valuable tool for the study of circumstellar nebulae. A simple model is presented to predict the percentage of circular polarization produced by scattering from the dust contained within such nebulae; it was found that a significant component of circular polarization can be produced in nebulae which have a net linear polarization. Possible observations of the red supergiants mu Cep and alpha Ori are given as examples.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal; 85; Nov. 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 181
    facet.materialart.
    Unknown
    A suggestion concerning the generation of the physical state of stellar mantles (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The physical state of the winds of B supergiants varies from one of a high level of ionization and rapid outflow to one of relatively low ionization and a moderate rate of outflow as one goes from type B0 to type A0. It is proposed here that this is the result of magnetodynamic energy being released in the mantles of these stars, much as occurs in the sun. Data are presented to show that this idea is plausible. It is noted that the release of magnetodynamic energy as the result of interaction between magnetic fields and differential motion in an inhomogeneous structure is probably the cause of the heating in all outer stellar atmospheres (mantles). In the late-type stars, the material in the mantle must first be ionized by the deposition of energy from acoustic waves; in the early-type stars, the material is already ionized at least once in the photosphere, as a result of the normal transfer of radiative energy, so no priming process is necessary for these stars.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 240
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 182
    facet.materialart.
    Unknown
    Influence of a stellar wind on the evolution of a star of 30 solar masses (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: A coarse grid of theoretical evolutionary tracks was calculated for a 30 solar mass star to determine the role of mass loss in the evolution of the star during core He burning. The Cox-Stewart opacities were applied, and the rate of mass loss, criterion for convection, and initial chemical composition were taken into consideration. Using the Schwarzschild criterion, the star undergoes little mass loss during core He burning and remains a blue supergiant separated from main sequence stars on the H-R diagram. The stellar remnant consists of the original He core and may appear bluer than equally luminous main sequence stars; a variety of possible evolutionary tracks can be obtained for an initial solar mass of 30 with proper choices of free parameters.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 240
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 183
    facet.materialart.
    Unknown
    Theoretical profiles for the 1-0 S/1/ H2 line in carbon stars (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The spectra of carbon stars have been synthesized from the models of Querci, Querci, and Tsuji and Querci and Querci in the region of the 1-0 S(1) vibration-rotation quadrupole line of H2. The line is shown to be sufficiently strong to be seen against the numerous lines of the CN red system for models with effective temperatures less than about 2700 K. The usefulness of the line as a diagnostic of the atmosphere is discussed, and a comparison with the measured spectra of UU Aur and S Cep is made. It is concluded that the outer atmospheric layers of carbon stars are significantly warmer than the models predict. An additional opacity source in the outer layers is required.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 240
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 184
    facet.materialart.
    Unknown
    The X-ray spectrum of QSO 0241 + 622 (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The X-ray spectrum of QSO 0241 + 622 in the range 2-50 keV measured with the Goddard Space Flight Center proportional counters on OSO 8 is presented. The quasar is similar to 3C 273 in the proportion of energy emitted in various bands, excluding the radio, if reported radiation above 50 keV from its direction is indeed associated with QSO 0241 + 622. Comparisons are made between the two quasars in a discussion of possible energy generation scenarios. Implications concerning quasar contributions to the diffuse background are discussed.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 240
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 185
    facet.materialart.
    Unknown
    The Penrose Photoproduction Scenario for NGC 4151 /PCS-SSC/ - A black hole gamma-ray emission mechanism for active galactic nuclei and Seyfert galaxies (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: On the basis of general arguments, it has been suggested (Bignami et al., 1979) that a steepening of the spectrum between X-ray and gamma-ray energies may be a general, gamma-ray characteristic of Seyfert galaxies, if the diffuse gamma-ray spectrum is considered to be a superposition of unresolved contributions, from one or more classes of extragalactic objects. It is shown that the above suggestion can be given a consistent theoretical interpretation in the context of the Penrose Photoproduction Scenario (PCS-SSC). Specifically in the case of NGC 4151, the dominant process will be shown to be Penrose Compton Scattering PCS in the ergosphere of a massive, central, rapidly spinning Kerr black hole, assumed in its nucleus. It is assumed that PCS gamma-ray induced electron-position, Synchrotron-Self-Compton processes 'evolve' as the dominant source of nonthermal X-rays.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 89; 3, Se; Sept
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 186
    facet.materialart.
    Unknown
    Coronal heating (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Theoretical arguments for coronal heating that take into account coronal structure are reviewed. Heating by the dissipation of electrical currents and heating by dissipation of waves are discussed. Loop structures in the solar corona are described.
    Keywords: ASTROPHYSICS
    Type: NASA. Goddard Space Flight Center The Sun as a Star; p 331-353
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 187
    facet.materialart.
    Unknown
    Global circulation and the solar dynamo (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The Sun is apparently rather typical of stars in its spectral class, with a convection zone of substantial depth and a modest rotation rate. These two factors are apparently enough to generate a substantial global circulation, seen so far principally as a differental rotation, as well as a nearly cyclic magnetohydrodynamic dynamo, seen principally as the 22 year "solar cycle". It would be expected therefore that many stars would have such dynamical characteristics. Recent observations of very large scale velocity fields of small velocity amplitude were reviewed.
    Keywords: ASTROPHYSICS
    Type: NASA. Goddard Space Flight Center The Sun as a Star; p 231-252
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 188
    facet.materialart.
    Unknown
    The Sun as a star (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The ways in which solar astrophysics serves to improve the methodology for the interpretation of stellar observations and the construction of stellar atmospheric models are summarized. The astrophysical processes highlighted are: stellar mass; stellar rotation; stellar magnetism; stellar composition; stellar companions; and evolutionary history.
    Keywords: ASTROPHYSICS
    Type: NASA. Goddard Space Flight Center The Sun as a Star; p 473-512
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 189
    facet.materialart.
    Unknown
    The solar corona and the solar wind (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: A stellar corona is an extended atmospheric region that is maintained at a significantly higher temperature than that of the stellar photosphere by nonthermal energy input. The solar corona stands as a prototype for all stellar coronas and is a prime example of a stellar atmosphere in which nonthermal processes predominate. Nonthermal processes are those in which the local flux of energy bears no direct relation to the internal energy of the gas or the quality of the radiation the gas emits and absorbs. Observations of the solar corona and the solar wind were surveyed and are presented.
    Keywords: ASTROPHYSICS
    Type: NASA. Goddard Space Flight Center The Sun as a Star; p 135-162
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 190
    facet.materialart.
    Unknown
    Dynamics of the solar photosphere (1981)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: Current knowledge of photospheric velocity fields is summarized. A model of the solar atmosphere is described along with the methods used in solar velocity field observations. The inferences drawn from integrated Sun observations, the velocity fields of the quiet Sun, sunspots, and other magnetic structures are discussed.
    Keywords: ASTROPHYSICS
    Type: NASA. Goddard Space Flight Center The Sun as a Star; p 11-64
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 191
    facet.materialart.
    Unknown
    Hydromagnetics and period changes in RR Lyrae stars (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Balazs-Detre and Detre have drawn an interesting parallel between the observed time scales of variability in the sun and in RR Lyrae stars. Additional information is presented here to support their conjecture that an analog of the solar magnetic cycle is operating in RR Lyrae stars. Rough considerations of the expected changes of photospheric radius and of magnetic energy content during a magnetic cycle suggest that the pulsation periods of these stars should also change in time. Within the large observational and theoretical uncertainties, the predicted period changes are compatible with those observed.
    Keywords: ASTROPHYSICS
    Type: Astronomical Society of the Pacific; vol. 92
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 192
    facet.materialart.
    Unknown
    Far-infrared survey of the galactic plane (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The galactic plane has been mapped from L = 352 deg to 45 deg in the band 100-300 microns with beam size of 30 arcmin. Latitudinal and longitudinal distribution of diffuse far-infrared (FIR) emission are given in addition to identifications of the prominent discrete sources with H II and CO emission. FIR luminosities are calculated for the nucleus and the surrounding disk.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 239
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 193
    facet.materialart.
    Unknown
    Primordial nucleosynthesis and Dirac's large numbers hypothesis (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Consideration is given to the analysis of Falik (1979) which attempted to show that the cosmological model proposed by Canuto and Hsieh (1978) in which the gravitational constant varies with time contradicts observations of primordial helium. It is shown that the analysis was based on the assumptions that (1) the energy density of radiation in local thermodynamic equilibrium is approximately equal to the fourth power of the equilibrium temperature, where the product of the equilibrium temperature with the scale factor of the Robertson-Walker metric is constant, and (2) the gravitational constant is approximately equal to the inverse of the time even at early cosmological epochs. These assumptions are demonstrated to be invalid in the scale covariant theory of gravitation used to develop the model, thus negating the conclusion that the Canuto and Hsieh model excludes the primordial synthesis of helium.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 239
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 194
    facet.materialart.
    Unknown
    Molecular clouds and galactic spiral structure (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Two large-scale 2.6 mm CO surveys of the galactic plane, one in the first quadrant (l = 12 to 60 deg, b = -1 to +1 deg), the other in the second (l = 105 to 139 deg, b = -3 to +3 deg), have provided evidence that, contrary to previous findings, molecular clouds constitute a highly specific tracer of spiral structure. Molecular counterparts of five of the classical 21-cm spiral arms have been identified: the Perseus arm, the local arm (including Lindblad's local expanding ring), the Sagittarius arm, the Scutum arm, and the 4-kpc arm. The region between the local arm and the Perseus arm is apparently devoid of molecular clouds, and the interarm regions of the inner Galaxy appear largely so. CO spiral structure implies that the mean lifetime of molecular clouds cannot be greater than 100 million years, the time required for interstellar matter to cross a spiral arm. Conservation of mass then sets a limit on the fraction of the interstellar medium in the form of molecular clouds: it cannot exceed one-half at any distance from the galactic center in the range 4-12 kpc.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 239
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 195
    facet.materialart.
    Unknown
    A search for FeH in M and S giants (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The strongest lines of FeH in the visible spectrum fall in the domain of TiO and ZrO bands. Analysis exists for TiO, but nothing is yet available for the weak but important ZrO lines. Using plate measurements and microphotometer tracings, high dispersion spectra of the following cool stars have been searched for FeH lines: Beta Peg, Mu UMa, Alpha Her, Omicron Cet, Chi Cyg, HR 105, HR 8714, R And, R Cyg, R Cam, T Sgr, R CMi, Cy Cyg, and RU Cam. The strongest FeH lines are unimpressive in R Cyg, where the strong infrared bands of FeH have already been identified. Identification of the blue-green FeH lines in other spectra must be considered inconclusive until a rotational analysis of the FeH spectrum is available.
    Keywords: ASTROPHYSICS
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 196
    facet.materialart.
    Unknown
    A galactic component of the diffuse X-ray flux in the range 2-7 keV (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: An analysis of the spatial distribution of the 2-7 keV X-ray background measured by Uhuru and reported by Schwartz (1979) is presented. The latitude distribution above 10 deg is consistent with a uniform isotropic component comprising the bulk of the radiation plus a galactic part varying from 3% at /b/ = 20 deg to 1% at /b/ = 90 deg. An analysis was made of the residual background based on the work of Warwick, Pye, and Fabian, in terms of a directional anisotropy as indicated by the Compton-Getting effect; the symmetrical galactic contribution was subtracted in the computations. It was shown that the results are consistent with the solar system moving through the 2-7 keV X-ray sea in the same manner as it appears to move with respect to the 2.7 K radiation.
    Keywords: ASTROPHYSICS
    Type: Royal Astronomical Society; vol. 192
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 197
    facet.materialart.
    Unknown
    Radiatively driven winds for different power law spectra (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The analytic solutions for radiatively driven winds are given for the case in which the winds are driven by absorption of line and continuum radiation. The wind solutions are analytically estimated for different parameters of the central source and for different power law spectra. For flat spectra, three sonic points can exist; it is shown, however, that only one of these sonic points is physically realistic. Parameters of the central source are given which generate winds of further interest for explaining the narrow and broad absorption lines in quasars. For the quasar model presented here, winds which could give rise to the narrow absorption lines are generated by central sources with parameters which are not realistic for quasars.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 86; 1-2,; June 198
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 198
    facet.materialart.
    Unknown
    X-ray spectrum of Kepler's supernova remnant (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Observations made with the Solid State Spectrometer (SSS) aboard the Einstein Observatory confirm Kepler's SNR as an X-ray source with an intensity between 1 and 3 keV of 7.2 x 10 to the -11th ergs/sq cm s. The X-ray spectrum is similar to those of Cas A and Tycho, with strong line emission from the helium-like species of Si, S, and Ar. Direct comparisons to Tycho's SNR suggest a distance to Kepler's SNR of not less than 5 kpc.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 237
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 199
    facet.materialart.
    Unknown
    X-ray and ultraviolet spectroscopy of Cygnus X-1 = HDE 226868 (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Observations of Cygnus X-1 with the solid-state spectrometer on the Einstein Observatory are presented. The X-ray spectra of two intensity dips viewed near superior conjunction did not exhibit increased photoelectric absorption. Rather, the data support a model in which an increase in the electron-scattering optical depth modifies both the observed spectrum and the intensity. The characteristic temperature of the intervening material is greater than about 50 million K. These measurements were in part simultaneous with observations by IUE. The ultraviolet spectrum and intensity remained relatively constant during an X-ray intensity dip.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 237
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 200
    facet.materialart.
    Unknown
    Collisions between grains in a turbulent gas (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Turbulent gas motions will induce random velocities of small dust grains that are imbedded in the gas. Within large eddies the friction forces from the gas lead to strongly correlated velocities for neighboring grains, whereas small eddies cause uncorrelated grain motions. The nonlinear response of a grain to eddy motion is calculated. This leads to a turbulent pressure within the dust component as well as to collisions between pairs of grains. The results are evaluated numerically for a Kolmogoroff spectrum and turbulent collision rates are calculated for molecular clouds and protostellar environments. Whereas grain-grain collisions should not modify the initial size distribution in molecular clouds to a significant extent, they will lead to an entirely different grain population in protostars.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics; 85; 3, Ma; May 1980
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...