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  • ASTROPHYSICS  (2,971)
  • 1980-1984  (2,970)
  • 1960-1964  (1)
  • 1
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    Meteoritics (1964)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Keywords: ASTROPHYSICS
    Type: NASA-TT-F-100 , NAS 1.77:F-100 , AD-A276988
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  • 2
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    The 1979 X-ray outburst of Centaurus X-4 (1980)
    In:  Other Sources
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    Publication Date: 2019-08-28
    Description: X-ray observations of the first major outburst of the classical transient X-ray source Centaurus X-4 since its discovery in 1969 are presented. The observations were obtained in May, 1979, with the all-sky monitor on board Ariel 5. The flare light curve is shown to exhibit many of the characteristics of other transients, including a double-peaked maximum, as well as significant, apparently random, variations and a lower peak flux and shorter duration than the 1969 event. Application of a standard epoch-folding technique to data corrected for linear decay trends indicates a possible source modulation at 0.3415 days (8.2 hours). Comparison of the results with previous other data on Cen X-4 and the characteristics of the soft X-ray transients allows a total X-ray output of approximately 3 x 10 to the 43rd ergs to be estimated, and reveals the duration and decay time of the 1979 Cen X-4 outburst to be the shortest yet observed from soft X-ray transients. The observations are explained in terms of episodic mass exchange from a late-type dwarf onto a neutron star companion in a relatively close binary system.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 241
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  • 3
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    Evaluation of orbits with incomplete knowledge of the mathematical expectancy and the matrix of covariation of errors (1980)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: The problem of selecting the optimal algorithm of filtration and the optimal composition of the measurements is examined assuming that the precise values of the mathematical expectancy and the matrix of covariation of errors are unknown. It is demonstrated that the optimal algorithm of filtration may be utilized for making some parameters more precise (for example, the parameters of the gravitational fields) after preliminary determination of the elements of the orbit by a simpler method of processing (for example, the method of least squares).
    Keywords: ASTROPHYSICS
    Type: NASA-TM-76237
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  • 4
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    Space superbubble 1200 light years across (1980)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Keywords: ASTROPHYSICS
    Type: NASA-NEWS-RELEASE-80-3 , P80-10003
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  • 5
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    Nature of type 1 Supernovae (1980)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: The nature of type 1 supernovae (SN 1) is discussed through a comparison of observational evidence and theoretical perspectives relating to both type 1 and 2 supernovae. In particular two hypotheses relating to SN 1 phenomenon are examined: the first proposing that SN 1 are components of binary systems in which, at a comparatively late stage of evolution, overflow of the mass occurs; the second considers pre-SN 1 to be recently evolved stars with a mass greater than 1.4 solar mass (white dwarfs). In addition, an explanation of the reduced frequency of flares of SN 1 in spiral galaxies as related to that in elliptical galaxies is presented.
    Keywords: ASTROPHYSICS
    Type: NASA-TM-76238 , PR-395
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  • 6
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    The evolution of massive stars (1982)
    In:  Other Sources
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    Publication Date: 2019-08-28
    Description: The hypotheses underlying theoretical studies of the evolution of massive model stars with and without mass loss are summarized. The evolutionary tracks followed by the models across theoretical Hertzsprung-Russell (HR) diagrams are compared with the observed distribution of B stars in an HR diagram. The pulsational properties of models of massive star are also described.
    Keywords: ASTROPHYSICS
    Type: B Stars With and Without Emission Lines, Parts 1 and 2; p 199-229
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  • 7
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    NASA sounding rockets to study eclipse (1980)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Keywords: ASTROPHYSICS
    Type: NASA-NEWS-RELEASE-80-24 , P80-10023
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  • 8
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    Long Periodic Terms in the Solar System (1982)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: The long period variations of the first eight planets in the solar system are studied. First, the Lagrangian solution is calculated and then the long period terms with fourth order eccentricities and inclinations are introduced into the perturbation function. A second approximation was made taking into account the short period terms' contribution, namely the perturbations of first order with respect to the masses. Special attention was paid to the determination of the integration constants. The relative importance of the different contributions is shown. It is useless, for example, to introduce the long period terms of fifth order if no account has been taken of the short period terms. Meanwhile, the terms that have been neglected would not introduce large changes in the integration constants. Even so, the calculation should be repeated with higher order short period terms and fifth order long periods.
    Keywords: ASTROPHYSICS
    Type: NASA-TM-76994 , NAS 1.15:76994
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  • 9
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    Infrared emission from M31 (1984)
    In:  Other Sources
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    Publication Date: 2019-08-28
    Description: Maps of M31 have been obtained at wavelengths of 12, 25, 60, and 100 microns. Emission is detected from the center and from a ring of 50 arcmin radius. The ring is that also seen in H I, in H II, and in radio continuum radiation. The spectrum of the central emission suggests a hotter dust temperature than in the ring. M31 is a weak infrared source, the radiation measured longward of 12 microns being only 3 percent of its total luminosity. The two closest companion galaxies, M32 and NGC 205, have also been detected.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 278; L59-L62
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  • 10
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    Infrared cirrus - New components of the extended infrared emission (1984)
    In:  Other Sources
    Details
    Publication Date: 2019-08-28
    Description: Extended sources of far-infrared emission superposed on the zodiacal and galactic backgrounds are found at high galactic latitudes and near the ecliptic plane. Clouds of interstellar dust at color temperatures as high as 35 K account for much of this complex structure, but the relationship to H I column density is not simple. Other features of the extended emission show the existence of warm structures within the solar system. Three bands of dust clouds at temperatures of 150-200 K appear within 10 deg on both sides of the ecliptic plane. Their ecliptic latitudes and derived distances suggest that they are associated with the main asteroid belt. A third component of the 100-micron cirrus, poorly correlated with H I, may represent cold material in the outer solar system or a new component of the interstellar medium.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 278; L19-L22
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  • 11
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    Observations of active chromosphere stars (1983)
    In:  Other Sources
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    Publication Date: 2019-08-28
    Description: It is pointed out that spectroscopic signatures of stellar chromospheric activity are readily observable. The present study is concerned with new photometric and spectroscopic observations of active-chromosphere RS CVn, BY Dra, and FK Com stars. Attention is given to the first results of a synoptic monitoring program of many active chromosphere stars. During the time from 1980 to 1982, photometric and spectroscopic observations of 10 known or suspected active-chromosphere objects were made. The results regarding the individual stars are discussed. Seven stars observed with the International Ultraviolet Explorer (IUE) are all spectroscopic binaries.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 275; 691-703
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  • 12
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    The states of Cygnus X-1 (1983)
    In:  Other Sources
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    Publication Date: 2019-08-28
    Description: HEAO 3 High Resolution Gamma-Ray Spectrometer observations of Cygnus X-1 in the 48-300 keV range, along with correlated 3-6 keV Ariel 5 data, have led to the identification of a new state for this object with low flux in both the soft and hard X-ray regions. This is followed by a slow increase in the hard X-ray flux to the normal low state of the source, characterized by a low intensity soft X-ray emission and a high intensity hard X-ray emission. The new 'superlow' state is interpreted in terms of the Compton model, where the X-ray emission arises from the scattering of low energy photons and one-billion K hot electrons. The superlow state may be seen as one extreme of a continuum of low state behavior, given that Compton cooling should begin to quench the hot electrons at higher soft X-ray fluxes, giving rise to the softer X-ray spectrum and to the anticorrelation in changes in the soft and hard X-ray fluxes.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 275; 307-315
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  • 13
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    Redshifts of high-temperature emission lines in the far-ultraviolet spectra of late-type stars (1983)
    In:  Other Sources
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    Publication Date: 2019-08-28
    Description: High-dispersion IUE spectra of six late-type stars exhibit small but statistically significant differential redshifts of high-temperature emission lines, like Si IV and C IV, with respect to low-temperature lines like S I and O I. A well-exposed, small-aperture spectrum of the active chromosphere binary Capella (Alpha Aurigae A: G6 II+F9 III) establishes that the high-temperature lines are redshifted in an absolute sense with respect to the accurately determined photospheric velocity of the system at single-line phase 0.50. Several possible explanations for the stellar redshifts are discused, including a warm wind (100,000 K) in which aparent redshifts are produced in optically thick lines by an accelerating outfow, and the downflowing component of a vertical circulation system for which the up-leg portion of the flow is too cool, too hot, or too tenuous to be visible in Si IV and C IV. If the second scenario is true, the stellar redshifts may provide an important phenomenological link to the downflows observed in 100,000 K species over magnetic active regions in the sun.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 274; 801-814
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  • 14
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    Inferences on the Thermodynamic Characteristics of a Star from the Observed Distinctive Radial Sequences of the Distinctive Atmospheric Regions Comprising that Stellar Atmosphere (1983)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: The implications of observational findings on atmospheric and subatmospheric taxonomy, diagnostics, and modeling are explored. The correlations between distinctive radial sequences in stellar atmospheres and the thermodynamic properties of the stars in which they appear are discussed.
    Keywords: ASTROPHYSICS
    Type: Stellar Atmospheric Struct. Patterns; p 333-349
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  • 15
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    Observed Distinctive Radial Sequences of the Distinctive Atmospheric Regions Comprising Stellar Atmospheres (1983)
    In:  CASI
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    Publication Date: 2019-08-28
    Description: Gross distinctive radial sequences of stellar atmospheric regions are identified and characterized observationally and thermodynamically. Sequences which include quasi-thermal photospheres, ejected shell photospheres, and spherically pulsating photospheres are discussed.
    Keywords: ASTROPHYSICS
    Type: Stellar Atmospheric Struct. Patterns; p 323-331
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  • 16
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    Speculative-theoretical Modeling of the Atmosphere Enveloping a Hypothetical (closed, Thermal) Star (1983)
    In:  CASI
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    Publication Date: 2019-08-28
    Description: The predictions of theoretical stellar atmospheric structural modeling and the theoretical picture of the local stellar environment as derived from the speculation that stars are (closed, thermal) thermodynamic systems, are summarized. The definition and representation of space- and state-fluxes is discussed and both classical (local thermodynamic equilibrium) and neoclassical (non-local thermodynamic equilibrium) thermal models are addressed.
    Keywords: ASTROPHYSICS
    Type: Stellar Atmospheric Struct. Patterns; p 19-113
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  • 17
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    Characteristics of Distinctive Regions Comprising Stellar Atmospheres (1983)
    In:  CASI
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    Publication Date: 2019-08-28
    Description: Empirically identified atmospheric regions whose existence and properties generally have no classical-theoretical basis are discussed. The quasi-thermal photosphere, chromosphere, lower corona, upper corona, non-decelerated post corona, decelerated post corona, and the H sub alpha emission envelope are defined. The observational phenomena, thermodynamic mechanisms, and diagnostic aspects associated with each of the atmospheric layers are described.
    Keywords: ASTROPHYSICS
    Type: Stellar Atmospheric Struct. Patterns; p 279-322
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  • 18
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    Gamma Ray Astrophysics: New insight into the universe (1981)
    In:  CASI
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    Publication Date: 2019-08-28
    Description: Gamma ray observations of the solar system, the galaxy and extragalactic radiation are reported. Topics include: planets, comets, and asteroids; solar observations; interstellar medium and galactic structure; compact objects; cosmology; and diffuse radiation. The instrumentation used in gamma ray astronomy in covered along with techniques for the analysis of observational spectra.
    Keywords: ASTROPHYSICS
    Type: NASA-SP-453 , NAS 1.21:453 , LC-81-600116
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  • 19
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    The A-stars: Problems and perspectives. Monograph series on nonthermal phenomena in stellar atmospheres (1983)
    In:  CASI
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    Publication Date: 2019-08-28
    Description: Normal A type stars, nonradiative heating in A type stars, magnetic Ap stars. The Am stars, the delta Scu stars, A supergiants, peculiar B type stars, and model atmospheres are addressed.
    Keywords: ASTROPHYSICS
    Type: NASA-SP-463 , NAS 1.21:463 , LC-83-061448
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  • 20
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    Radial velocity study of four southern RS CVn candidates and related field stars (1980)
    In:  Other Sources
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    Publication Date: 2019-08-28
    Description: Radial velocity variations are demonstrated for four southern RS CVn candidates: HD 39937, 101379, 155555, and 174429. The period of HD 155555 appears to have decreased by about one part in 100,000 over the past 18 yr. In addition, high-resolution observations of the Ca II H and K profiles and the Mg II 2800-A emission doublet are presented. These enhance the likelihood of these being RS CVn objects. Radial velocity data for 15 other late-type bright field stars are presented. Some of these were observed by Copernicus and may exhibit unusual chromospheres, while the rest lack radial velocity information as tabulated in the Bright Star Catalog. All velocity measures have been corrected to the IAU heliocentric system.
    Keywords: ASTROPHYSICS
    Type: Astronomical Journal; 85; July 198
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  • 21
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    New method for determining the distances to certain extragalactic radio sources (1980)
    In:  CASI
    Details
    Publication Date: 2019-08-28
    Description: The structural evolution of variable radio sources is examined in the Hedgehog model. It is shown that the time evolution of the angular separation of two components is described by the ellipse equation.
    Keywords: ASTROPHYSICS
    Type: NASA-TM-76209 , PR-325
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  • 22
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    Changes in the ultraviolet spectrum of EG Andromedae (1984)
    In:  Other Sources
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    Publication Date: 2019-08-27
    Description: Ultraviolet observations of EG Andromedae, a symbiotic star, are reported which clearly show pronounced eclipse-like effects on the high-temperature far-UV continuum. Continuum and emission-line variations with phase are reported and related to synoptic hydrogen alpha data. System parameters are characterized.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 281; L75-L77
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  • 23
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    Observations of two peculiar emission objects in the Large Magellanic Cloud (1983)
    In:  Other Sources
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    Publication Date: 2019-08-27
    Description: Ultraviolet and visual wavelength spectra were obtained of two peculiar emission objects, Henize S63 and Sanduleak's star in the Large Magellanic Cloud. Previously not observed in the near- or far-ultraviolet, both objects exhibit strong permitted and semiforbidden line emissions. Estimates based on the absolute continuum flux of the hot companion star in Hen S63 indicate that it rivals the luminosity of the carbon star primary. The emission-line profile structure in both objects does not suggest Wolf-Rayet type emission. Carbon in Sanduleak's star (LMC anonymous) is conspicuously absent, while N V, semiforbidden N IV, and semiforbidden N III dominate the UV emission-line spectrum. Nitrogen is overabundant with respect to carbon and oxygen in both objects. The large overabundance of nitrogen in Sanduleak's star suggests evidence for CNO processes material similar to that seen in Nu Car.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 1 (ISSN 0004-637X); 275; 584-591
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  • 24
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    Evidence for a warm wind from the red star in symbiotic binaries (1983)
    In:  Other Sources
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    Publication Date: 2019-08-27
    Description: A systematic redshift of the high ionization resonance emission lines with respect to the intercombination lines is found from an examination of the ultraviolet spectra of symbiotic stars obtained with IUE. After consideration of other possibilities, this is most probably explained by photon scattering in an expanding envelope optically thick to the resonance lines. Line formation in a wind, or at the base of a wind is therefore suggested. Reasons are also given indicating line formation of the most ionized species in a region with an electron temperature of the order of 100,000 K, probably around the cool star. The behavior of the emission line width with ionization energy seems to support this model. The cool components of symbiotic stars appear to differ from normal red giants, which do not have winds of this temperature. An explanation in terms of a higher rotation velocity due to the binary nature of these stars is suggested.
    Keywords: ASTROPHYSICS
    Type: Astronomy and Astrophysics (ISSN 0004-6361); 126; 2, Oc
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  • 25
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    Stellar atmospheric structural patterns (1983)
    In:  CASI
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    Publication Date: 2019-08-27
    Description: The thermodynamics of stellar atmospheres is discussed. Particular attention is given to the relation between theoretical modeling and empirical evidence. The characteristics of distinctive atmospheric regions and their radical structures are discussed.
    Keywords: ASTROPHYSICS
    Type: NASA-SP-471 , NAS 1.21:471 , LC-83-20242
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  • 26
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    Empirical-theoretical Survey of the Variety of Peculiarities and Anomalies in the Atmospheres Enveloping Actual Stars (1983)
    In:  CASI
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    Publication Date: 2019-08-27
    Description: Phenomena observed in actual stellar atmospheres which contradict the speculative, standard thermal atmospheric model are discussed. Examples of stellar variability, emission line peculiarity, symbiotic stars and phenomena, extended atmosphere stars, superionization, and superthermic velocity are examined.
    Keywords: ASTROPHYSICS
    Type: Stellar Atmospheric Struct. Patterns; p 115-264
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  • 27
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    The narrow ultraviolet emission lines of the red dwarf Au Microscopii (dM1.6e) (1983)
    In:  Other Sources
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    Publication Date: 2019-08-27
    Description: It is pointed out that the red dwarfs are the smallest, coolest, faintest, least massive, but most common of normal main-sequence stars. The dMe (H-alpha emission) subclass of the red dwarfs exhibits the largest median soft X-ray to bolometric luminosity ratio of any group of late-type stars. In connection with the present investigation, attention is given to the first high-dispersion spectra of the chromospheric (6000 K) and higher temperature (up to 100,000 K) emissions of a dMe star, AU Microscopii in the far-ultraviolet (1150-2000 A) and middle-ultraviolet (2000-3000 A) bands accessible to the International Ultraviolet Explorer (IUE). AU Mic is one of the most luminous of lower main-sequence stars in C IV and soft X-ray emission.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal, Part 2 - Letters to the Editor (ISSN 0004-637X); 270; July 1
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  • 28
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    International Ultraviolet Explorer observations of amorphous hot galaxies (1984)
    In:  CASI
    Details
    Publication Date: 2019-08-14
    Description: In order to better understand the nature of star formation processes in amorphous galaxies, short wavelength International Ultraviolet Explorer (IUE) spectra of galaxies NGC 1705 and NGC 1800 were obtained. The IUE data for NGC 1705 were of excellent quality while the low signal-to-noise NGC 1800 observation was useful only as a rough guide to the ultraviolet energy distribution. It was found that NGC 1705 contains a normal mix of OB stars, which is consistent with the nearly constant recent star formation rate inferred from new optical data. The NGC 1800 is likely to have similar properties, and blue galaxies with amorphous structures thus do not show evidence for anomalies in stellar mass distributions. The UV spectra of amorphous galaxies and a variety of other hot extragalactic stellar systems have similar characteristics, which suggests OB stellar populations often are homogeneous in their properties.
    Keywords: ASTROPHYSICS
    Type: NASA-CR-174354 , NAS 1.26:174354 , IAP-84-22
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  • 29
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    The cosmos today and tomorrow (1980)
    In:  CASI
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    Publication Date: 2019-08-13
    Description: The book ""Tested on Oneself'' is summarized and reviewed. Topics in the field of space flight and aerospace medicine are addressed.
    Keywords: ASTROPHYSICS
    Type: NASA-TM-75736
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  • 30
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    High resolution observations of magnesium II 2800 A in Alpha Centauri A - The density of interstellar magnesium II and the stellar chromospheric profiles (1982)
    In:  Other Sources
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    Publication Date: 2019-08-13
    Description: The profiles are virtually identical with the solar profiles except for the presence of an absorption feature near line center in the h and k lines of Alpha Centauri A. It is found that this absorption feature can be explained by interstellar absorption of Mg II along the line of sight. The average density of Mg II is found to be 2.75 plus or minus 0.7 x 10 to the -7th/cu cm, in good agreement with the previously determined values in the solar vicinity in the direction of Alpha CMa and Alpha Lyr.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 252
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  • 31
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    Mercury in a thin layer in HgMn stars - A test of a diffusion model (1980)
    In:  Other Sources
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    Publication Date: 2019-08-13
    Description: Lines of the first three states of ionization of mercury have been observed in Mu Leporis and Chi Lupi using the Copernicus satellite. Lines of Hg II and Hg III have been observed in Alpha Andromedae. There appears to be an absorption feature at every wavelength where there is expected to be a mercury line. The presence of all three states of ionization is likely in Mu Lep and Chi Lup. The relative equivalent widths of the lines of the various states of ionization do not depend on the effective temperature of the stars, in contradiction to what is expected if mercury were uniformly distributed in the atmosphere. It is, however, expected if mercury has been concentrated, by diffusion, in a thin layer, where the radiative forces just equal the gravitational forces on mercury. That mercury should be so concentrated is also required by the explanation of the mercury isotope anomaly proposed by Michaud, Reeves, and Charland.
    Keywords: ASTROPHYSICS
    Type: Astrophysical Journal; vol. 239
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  • 32
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    Observations of Local Interstellar Mg I and Mg II (1984)
    In:  CASI
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    Publication Date: 2019-08-13
    Description: Copernicus and IUE observations of 5 stars within 50 pc of the Sun were combined to study the ionization of magnesium in the local interstellar medium (LISM). The high resolution Copernicus spectrometer was used to detect interstellar MG I 2852 in the spectra of alpha Gru, alpha Eri, and alpha Lyr, while placing upper limits on Mg I in the spectra of alpha CMa and alpha PsA. Observations of Mg II 2795, 2802 for these stars were also obtained with IUE and Copernicus. The column densities of Mg I and Mg II are used to place constraints on the temperature of the LISM.
    Keywords: ASTROPHYSICS
    Type: Local Interstellar Medium, No. 81; p 64-66
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  • 33
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    An X-ray survey of supernova remnants in the Large Magellanic Cloud (1982)
    In:  Other Sources
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    Publication Date: 2019-07-27
    Description: Preliminary observation results for SNRs in the LMC are presented, and the current status of programs investigating these observational data is assessed. High Resolution Imager maps indicate that the remnant diameters used in early rate calculations were systematically underestimated. A preliminary SN rate of 1/110-350 years is derived upon reconsideration of these data. It is noted that most of the remnants detected in the LMC have very soft spectra, and would be undetectable as X-ray sources at distances of 5-10 kpc in the galactic plane.
    Keywords: ASTROPHYSICS
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    An optimist's guide to supernovae (1982)
    In:  Other Sources
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    Publication Date: 2019-07-27
    Description: There are some hints that a satisfactory agreement between observations and models is developing in several areas of supernova research. The light curves and spectra of Type I supernovae look so much like the models that they may well have their origin in the synthesis of Ni-56 in the explosion of a compact star. Type II supernovae are found where massive stars form, have light curves that correspond to 10 to the 51st ergs suddenly deposited inside a red supergiant, and may in fact be the explosions of massive stars. Some young supernova remnants, such as Cas A, show abundance patterns that bear a striking resemblance to those seen deep inside models of massive stars on the verge of destruction. Observations of old supernova remnants provide energy estimate of 10 to the 51st ergs - just the amount needed for the models of the outbursts.
    Keywords: ASTROPHYSICS
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    Supernovae and the formation of galaxies (1982)
    In:  Other Sources
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    Publication Date: 2019-07-27
    Description: Attention is given to the cumulative effect of many SNs in a galaxy, especially a young galaxy, as well as the effect of the blast wave resulting from the combination of all individual SNs on the intergalactic medium (IGM). It is suggested that the IGM can be shock-heated by this process, so that in the late stages of an individual expanding galaxy's shock a shell may form whose mass is many times greater than that of the seed galaxy. If this shell fragments, due to gravitational instability, it will give rise to a new generation of galaxies. SN explosions may thereby provide a hydrodynamic amplifier of some significance in the process of galaxy formation.
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    X-ray spectroscopy and imagery of supernova remnants with the Einstein Observatory (1982)
    In:  Other Sources
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    Publication Date: 2019-07-27
    Description: The two complementary spectroscopic instruments of the Einsten Observatory make possible X-ray spectroscopy of SNRs with considerably increased sensitivity and spectral resolution. The Solid State Spectrometer is a cryogenically cooled detector with 160 eV resolution, which suffices not only for the separation of lines due to different elements, but also the resolution of H-like, He-like and neutral lines from the same element for Si and above. The Focal Plane Crystal Spectrometer uses Bragg crystals to achieve excellent spectral resolution, but at the expense of sensitivity. Both instruments operate over most of the 0.2-4 keV energy band of the Einstein telescope, and are able to detect most of the important X-ray lines except the K lines of Fe and Ni.
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  • 37
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    Supernovae and the origin of the solar system (1982)
    In:  Other Sources
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    Publication Date: 2019-07-27
    Description: A review is presented of the astrophysical reasoning that links supernovae to the origin of the solar system. Topics examined concerning the supernova connections include the abundances of the nuclides at the time the solar system formed, the collapse of a solar cloud by supernova triggering, the origins of isotopic anomalies in solar system samples, and the sputtering of interstellar dust with the attendant chemical and isotopic evolution of the interstellar medium. The controversies surrounding each of these topics are critically examined, focusing on the issues arising from the discovery of the isotopic anomalies in meteorites.
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  • 38
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    The origin of the Crab Nebula and electron capture supernova of 8-10 solar-mass stars (1982)
    In:  Other Sources
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    Publication Date: 2019-07-27
    Description: (Previously announced in STAR as N81-32097)
    Keywords: ASTROPHYSICS
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  • 39
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    X-rays from Wolf-Rayet stars observed by the Einstein Observatory (1982)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Preliminary results of three X-ray surveys are presented. Out of a sample of 20 stars, X-rays were detected from four Wolf-Rayet stars and two O8f(+) stars. The detected stars have about the same mean value as O stars for the X-ray to total luminosity ratio, L(x)/L = 10 to the -7th, but exhibit a much larger variation about the mean. The spectral energy distributions are also found to be like that of O stars in that they do not exhibit large attenuation of X-rays softer than 1 keV. This indicates that for both the O stars and WR stars much of the X-ray emission is coming from hot wisps or shocks in the outer regions of the winds and not from a thin source at the base of the wind. The general spectral shape and flux level place severe restrictions on models that attribute the lack of hydrogen emission lines to extremely high temperatures of the gas in the wind.
    Keywords: ASTROPHYSICS
    Type: In: Wolf-Rayet stars: Observations, physics, evolution; Sep 18, 1981 - Sep 22, 1981; Cozumel; Mexico
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  • 40
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    Chemical composition of Wolf-Rayet stars - Abundant evidence for anomalies (1982)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Keywords: ASTROPHYSICS
    Type: In: Wolf-Rayet stars: Observations, physics, evolution; Sep 18, 1981 - Sep 22, 1981; Cozumel; Mexico
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  • 41
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    Hot mantles, moderate photospheres for Wolf-Rayet stars (1982)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: The amount of continuous energy from Wolf-Rayet stars and the shape of the continuous spectrum from the ultraviolet to the near infrared correspond to effective temperatures in the range 25,000 to 30,000 K. The value of log g is of the order of 4.0 + or - 0.5. Thus the photospheres of Wolf-Rayet stars correspond to those of moderately hot stars. The line spectra of Wolf-Rayet stars, however, indicate that electron temperatures greater than 30,000 K occur in the outer atmospheres or mantles of these stars. Here outflow is important.
    Keywords: ASTROPHYSICS
    Type: In: Wolf-Rayet stars: Observations, physics, evolution; Sep 18, 1981 - Sep 22, 1981; Cozumel; Mexico
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  • 42
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    Subluminous Wolf-Rayet stars - Observations (1982)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Even though the loss of the outer, H-rich envelope may be a necessary condition for forming WR stars, it is clearly not a sufficient one. This is because the majority of planetary nuclei do not have a WR-type spectrum. The question why some central stars are WR stars while others are, say, O stars is addressed here. The question is approached by ascertaining how the properties of WR-type central stars differ from those of O-type stars. The study therefore begins with the classification and calibration of WR spectra. It is found that whereas the WR phenomenon may occur in stars of any mass, it is limited to stars that have been stripped (or mixed) down to their cores. The fact of prior envelope loss, however, is not sufficient to predict which stars will develop WR characteristics. Instead, a comprehensive description of envelope loss, including a detailed accounting of interior conditions and processes at the core envelope interface, will be required to explain the onset of WR characteristics.
    Keywords: ASTROPHYSICS
    Type: In: Wolf-Rayet stars: Observations, physics, evolution; Sep 18, 1981 - Sep 22, 1981; Cozumel; Mexico
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  • 43
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    Wolf-Rayet phenomena (1982)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: An outline is presented of what is currently known about the properties of stars showing Wolf-Rayet (W-R) phenomena, taking into account also the directions in which future work is leading. W-R spectra are found to be primarily an emission line spectrum superimposed on a 'hot' continuous spectrum. P Cygni absorption components are observed for some lines in some stars. A fact not realized when Thomas (1968) discussed W-R spectra is that a very few W-R stars have intrinsic absorption lines. On the basis of the spectroscopic observations, it could now be inferred that an optically thick stellar wind is involved. Many of the WN subtypes do contain some carbon. The WC subtypes contain little or no nitrogen. Attention is given to absolute visual magnitudes of W-R stars, the heterogeneity of W-R spectra, transition W-R spectra, mass loss rates, very luminous W-R objects, theoretical aspects of stellar structure and stellar winds, and evolutionary scenarios.
    Keywords: ASTROPHYSICS
    Type: In: Wolf-Rayet stars: Observations, physics, evolution; Sep 18, 1981 - Sep 22, 1981; Cozumel; Mexico
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    The very unusual ultraviolet spectra of R Arae (1982)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: The high resolution ultraviolet spectra of the 4.4-day period binary R Arae, observed in 1980 with the International Ultraviolet Explorer, show that its continuum flux level varied outside the eclipse by more than a factor of two in ten days, and by over 50 percent within the same orbital cycle. The flux level varied nonmonotonically at different wavelengths. The resonance lines of Mg II and Si IV exhibited shortward-shifted absorption components near phase 0.4, indicating the presence of a gas stream toward the observer at a velocity of some -450 to -500 km/s. The observations of R Arae with the Einstein satellite show it to be an X-ray source.
    Keywords: ASTROPHYSICS
    Type: Binary and multiple stars as tracers of stellar evolution; Aug 31, 1981 - Sep 03, 1981; Bamberg
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  • 45
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    Mass flow due to heating in a binary system - Application to U Cephei (1982)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: The possibility of mass flow due to the heating of the cooler component in a close binary system has been investigated. The heating may be caused by irradiation from the hotter companion or by other mechanisms such as the spacial coincidence of non-linear 'g-mode' oscillations in the cooler star. The 2.4-day period binary U Cep, in which gas streaming has been observed, has been chosen for model calculations. Preliminary results show that such a heating of the lower atmosphere of the cooler star could lead to mass flow at an average rate of 10 to the -9th - 10 to the -7th solar mass per year without the star necessarily filling its critical Roche surface.
    Keywords: ASTROPHYSICS
    Type: Binary and multiple stars as tracers of stellar evolution; Aug 31, 1981 - Sep 03, 1981; Bamberg
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  • 46
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    Ultraviolet light curves of U Geminorum and VW Hydri (1982)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: (Previously announced in STAR as N82-21117)
    Keywords: ASTROPHYSICS
    Type: Binary and multiple stars as tracers of stellar evolution; Aug 31, 1981 - Sep 03, 1981; Bamberg
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    The evolutionary state of zeta Aurigae (1982)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Ultraviolet studies, originally undertaken to ascertain the state of the atmosphere of the K-supergiant component of the zeta Aurigae system, have been sidetracked by the discovery of significant accretion effects. An analysis of the phase dependence of the profiles of resonance lines in Mg II and C IV has led to a qualitative model of the wind flow from the K star. At the position of the B star the flow velocity is about 100 km/sec and the density is 0.000003 per cu cm, leading to a mass loss rate of 2 x 10 to the -8th solar masses per year. This wind interacts with the B star in a shock, which will be described, leading to accretion on the B star at a rate of 4 x 10 to the -10th solar masses per year.
    Keywords: ASTROPHYSICS
    Type: Binary and multiple stars as tracers of stellar evolution; Aug 31, 1981 - Sep 03, 1981; Bamberg
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  • 48
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    BL Lac objects and their associated galaxies (1982)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: CCD photometry of five BL Lac objects indicates that at least three, and possibly four, are located at the centers of giant elliptical galaxies. The redshift for one of these objects, 1218+304, is estimated. A lower limit is placed on the redshift of 1219+28, for which no associated galaxy has been detected. Separation of the galaxy emission from the total observed flux makes possible comparison of the optical - far red flux from the point source alone with radio and X-ray data. This comparison suggests the emission from 1727+50 and 1218+304 can be interpreted as due to direct synchrotron emission. Observations of a small group of galaxies associated with the BL Lac object 1400+162 are also discussed.
    Keywords: ASTROPHYSICS
    Type: Extragalactic radio sources; Aug 03, 1981 - Aug 07, 1981; Albuquerque, NM
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    A search for HI in elliptical galaxies with nuclear radio sources (1982)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Keywords: ASTROPHYSICS
    Type: Extragalactic radio sources; Aug 03, 1981 - Aug 07, 1981; Albuquerque, NM
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  • 50
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    Supercritical accretion and its possible relation to quasars and radio sources (1982)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Keywords: ASTROPHYSICS
    Type: Extragalactic radio sources; Aug 03, 1981 - Aug 07, 1981; Albuquerque, NM
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  • 51
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    Superluminal motion in NRAO 140 and a possible future method for constraining H/0/ and q/0/ (1982)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: In order to test the prediction that the compact components in NRAO 140 should appear to separate at a speed exceeding about 4c, further VLBI observations of NRAO 140 at 2.8 cm were obtained in February 1981 and June 1981. The correlated flux densities and closure phases show clear, systematic changes compared with April 1980 data that are modeled very well by an increase in the separation of the compact components corresponding to velocities of separation ranging from 6.7c to 12c for cosmological distances and H(0) = 50 and q(0) = 0. When H(0) = 100 and q(0) = 1, the range is 2.1c to 3.7c. From these results, a prescription for the determination of upper limits to the cosmological parameters H(0) and q(0) is outlined.
    Keywords: ASTROPHYSICS
    Type: Extragalactic radio sources; Aug 03, 1981 - Aug 07, 1981; Albuquerque, NM
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    VLBI observations of M87 (1982)
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    Publication Date: 2019-07-13
    Description: Results of VLBI observations of the nucleus and jet of M87 at 1666.6 MHz in right circular polarization are presented. A hybrid map of the nucleus was made revealing the presence of a one-sided jet, whose position angle is 290.5 (+ or - 1) deg. Assuming that no counter-jet exists because of the effects of relativistic beaming, limits can be placed on the flow velocity of the jet, and the resulting ratio of the observed intensities of the jet to the counter-jet explains the absence of the counter-jet. Another explanation is that jets are intrinsically one-sided, or that counter-jet observed emissions are delayed. Finally, the possibility of existing small wiggles is considered, but further observations are required to verify their existence in M87.
    Keywords: ASTROPHYSICS
    Type: Extragalactic radio sources; Aug 03, 1981 - Aug 07, 1981; Albuquerque, NM
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  • 53
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    SS433 - Periodic changes in the radio structure of scale size 10 to the 16th cm (1982)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Keywords: ASTROPHYSICS
    Type: Extragalactic radio sources; Aug 03, 1981 - Aug 07, 1981; Albuquerque, NM
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  • 54
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    VLBI observations of the nucleus of Centaurus A (1982)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Keywords: ASTROPHYSICS
    Type: Extragalactic radio sources; Aug 03, 1981 - Aug 07, 1981; Albuquerque, NM
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  • 55
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    Radio and X-ray structure of Centaurus A (1982)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Recent studies of the nearby radio galaxy Centaurus A with the Very Large Array and the Einstein X-Ray Observatory reveal complex radio and X-ray structures. A prominent one-sided jet comprised of resolved knots located 0.2-6 kpc from the nucleus is seen in both radio and X-rays. The X-ray emission is probably synchrotron, requiring in situ reacceleration up to about ten million. Inverse Compton emission is not a likely explanation though a thermal model in which the nucleus ejects dense 100,000 solar mass clouds cannot be excluded. An elongated X-ray region is also found near the 'middle' radio lobe and optical HII regions about 30 kpc NE of the nucleus. Conditions around the active nucleus, the absence of X-rays from the inner radio lobes, and X-ray evidence for a hot interstellar medium are briefly discussed
    Keywords: ASTROPHYSICS
    Type: Extragalactic radio sources; Aug 03, 1981 - Aug 07, 1981; Albuquerque, NM
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    A morphological classification of clusters of galaxies from Einstein images (1982)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: The earliest Uhuru observations showed that cluster X-ray sources were not associated with single individual galaxies but were extended sources. It has only been with the advent of the Einstein X-ray imaging observatory that a first look at cluster X-ray morphology and classification has been possible. The proposed classification system divides clusters into two families, including those with and those without X-ray dominant galaxies. Within each family, the dynamical indicators display a full range of values. One subgroup of clusters is those whose X-ray emission is not regular and which do not contain an X-ray dominant galaxy. One of the brighter, nearer and best studied members of this class is Al367. From the X-ray imaging observations, four clusters have been discovered to have double structure in their surface brightness distributions. The Coma cluster is the archtype of an evolved, fully relaxed cluster. Ellipticals in the Virgo core include M87, M86, and M84. It is concluded that the cluster images are useful in determining the cluster family and the cluster's dynamical state.
    Keywords: ASTROPHYSICS
    Type: Extragalactic radio sources; Aug 03, 1981 - Aug 07, 1981; Albuquerque, NM
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    A new view of baryon symmetric cosmology based on grand unified theories (1982)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: (Previously announced in STAR as N82-10969)
    Keywords: ASTROPHYSICS
    Type: In: Progress in cosmology; Sep 14, 1981 - Sep 18, 1981; Oxford
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  • 58
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    The symbiotics as binary stars (1982)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: According to the original definition, symbiotic stars have combination spectra, in which the high-excitation emission lines regularly found in planetary nebulae are superposed on a low-temperature absorption spectrum. In connection with this investigation, the coexistence of a He II emission with the TiO absorption bands is also postulated. Attention is given to a summary of observed properties of symbiotics, binaries with a late-type giant component, possible models for the symbiotics, models with an accreting main-sequence star (Algol symbiotics), T Coronae borealis as a possible cataclysmic Algol-type symbiotic, binaries with rejuvenated degenerate dwarfs (novalike symbiotics), questions regarding the existence of PN symbiotics or subdwarfs unpowered by accretion, and related binary systems which are not symbiotics.
    Keywords: ASTROPHYSICS
    Type: In: The nature of symbiotic stars; Aug 26, 1981 - Aug 28, 1981; Alpes-de-Haute-Provence; France
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    AR Pavonis - The Rosetta Stone of the symbiotics (1982)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: AR Pav is considered with respect to the early history and observations, the light curve, spectroscopic properties, and recent observations. It is suggested that recent observations tend to confirm the validity of the binary model proposed for AR Pav by Thackeray and Hutchings (1974). The secondary appears as an M3 giant showing normal infrared properties. The nature of the hot primary, however, remains uncertain as it appears obscured by an accretion 'shell' both during and outside of eclipse.
    Keywords: ASTROPHYSICS
    Type: In: The nature of symbiotic stars; Aug 26, 1981 - Aug 28, 1981; Alpes-de-Haute-Provence; France
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  • 60
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    The peculiar star RX Puppis (1982)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: The first high dispersion observations of RX Puppis in the wavelength region 1200-3200 A were obtained with the International Ultraviolet Explorer. The anomalies observed in lines such as He II, semiforbidden C III, C IV, semiforbidden N III, semiforbidden N IV, semiforbidden O III, and semiforbidden Si III, which show split line profiles and Doppler displaced components, suggest dynamic activity in circumstellar material that probably has the form of rings and/or gas streamers between the cool giant and the hot companion. The Mg II lines show P-Cygni structure arising in the Mira primary. The continuum cannot be due to a star earlier than AO II and it may arise in an accretion disk around the hot secondary. Moreover, the line emission requires photoionization either from a hot subdwarf or the inner accretion disk.
    Keywords: ASTROPHYSICS
    Type: In: The nature of symbiotic stars; Aug 26, 1981 - Aug 28, 1981; Alpes-de-Haute-Provence; France
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  • 61
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    UV time-dependent emission in SY Muscae (1982)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: IUE ultraviolet spectra of SY Mus for September 20, 1980 and June 11, 1981 indicate a substantial enhancement of UV emission over a nine-month period. The general UV flux level appears to have increased by about one order of magnitude between the two observing epochs. The strong UV continuum evident throughout the entire IUE spectral range 1200-3200 A on June 11, 1981 is closely approximated by a star with an effective temperature of 40,000 K. On September 20, 1980, however, the continuum distribution manifested a more complex structure, which is possibly explained by a combination of thermal emission from an early type main sequence star and nebular recombination emission.
    Keywords: ASTROPHYSICS
    Type: In: The nature of symbiotic stars; Aug 26, 1981 - Aug 28, 1981; Alpes-de-Haute-Provence; France
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  • 62
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    Constraints on neutrinos and axions from cosmology (1981)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: A review is made of the astrophysical arguments with regard to neutrino properties. It is shown that the best fit to the present baryon density and He-4 abundance is obtained with three neutrino species. It is also shown that astrophysical constraints on neutrino and axion lifetime-mass combinations rule out weakly interacting particles with lifetimes between 1/1000 to 10 to the 23rd sec for M up to 10 MeV. There is an allowed astrophysical window for neutrinos with M up to 10 MeV and tau less than 1000 sec. The possible role of massive neutrinos in the dark mass of galaxies is discussed. It is shown that the baryon density in the universe is comparable to the density obtained from the dynamics of binary galaxies. Therefore, massive neutrinos are only required if the cosmological mass density is greater than that implied by binaries and small groups of galaxies. The only objects which might imply such high densities are large clusters. For neutrinos to cluster with these large clusters requires a neutrino mass of at least 3 eV.
    Keywords: ASTROPHYSICS
    Type: Cosmology and particles; Mar 15, 1981 - Mar 21, 1981; Savoie; France
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  • 63
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    Fundamental tests of galaxy formation theory (1982)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: The structure of the universe as an environment where traces exist of the seed fluctuations from which galaxies formed is studied. The evolution of the density fluctuation modes that led to the eventual formation of matter inhomogeneities is reviewed, How the resulting clumps developed into galaxies and galaxy clusters acquiring characteristic masses, velocity dispersions, and metallicities, is discussed. Tests are described that utilize the large scale structure of the universe, including the dynamics of the local supercluster, the large scale matter distribution, and the anisotropy of the cosmic background radiation, to probe the earliest accessible stages of evolution. Finally, the role of particle physics is described with regard to its observable implications for galaxy formation.
    Keywords: ASTROPHYSICS
    Type: Astrophysical cosmology; Sep 28, 1981 - Oct 02, 1981; Vatican City State
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    The evolution of galaxies (1982)
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    Publication Date: 2019-07-13
    Description: The recent observational evidence on the evolution of galaxies is reviewed and related to the framework of current ideas for galaxy formation from primordial density fluctuations. Recent strong evidence for the evolution of the stellar population in ellipticals is presented, as well as evidence that not all ellipticals behave as predicted by any simple theory. The status of counts of faint galaxies and the implications for the evolution of spirals is discussed, together with a discussion of recent work on the redshift distribution of galaxies at faint magnitudes and a spectroscopic investigation of the Butcher-Oemler blue cluster galaxies. Finally a new picture for the formation and evolution of disk galaxies which may explain most of the features of the Hubble sequence is outlined.
    Keywords: ASTROPHYSICS
    Type: Astrophysical cosmology; Sep 28, 1981 - Oct 02, 1981; Vatican City State
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    H0, q0 and the local velocity field (1982)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: An attempt is made to find a systematic deviation from linearity for distances that are under the control of the Virgo cluster, and to determine the value of the mean random motion about the systematic flow, in order to improve the measurement of the Hubble and the deceleration constants. The velocity-distance relation for large and intermediate distances is studied, and type I supernovae are calibrated relatively as distance indicators and absolutely to obtain a new value for the Hubble constant. Methods of determining the deceleration constant are assessed, including determination from direct measurement, mean luminosity density, virgocentric motion, and the time scale test. The very local velocity field is investigated, and a solution is preferred with a random peculiar radial velocity of very nearby field galaxies of 90-100 km/s, and a Virgocentric motion of the local group of 220 km/s, leading to an underlying expansion rate of 55, in satisfactory agreement with the global value.
    Keywords: ASTROPHYSICS
    Type: Astrophysical cosmology; Sep 28, 1981 - Oct 02, 1981; Vatican City State
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    Models for Type I supernovae (1980)
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    Publication Date: 2019-07-13
    Description: Two somewhat disjoint scenarios for Type I supernovae are presented. One scenario is based on mass accretion by a white dwarf in a binary system, while the other involves a star of 8 to 10 solar masses which may or may not be a solitary star. In spite of the apparent dissimilarities of the two models, it may be that each occurs to some extent in nature, for they both share the possibility of producing substantial quantities of Ni-56 and explosions in stars devoid of hydrogen envelopes. It is concluded that these are two properties that must be shared by any viable Type I model.
    Keywords: ASTROPHYSICS
    Type: In: Type I supernovae; Mar 17, 1980 - Mar 19, 1980; Austin, TX
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  • 67
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    Thermonuclear processes on accreting neutron stars (1981)
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    Publication Date: 2019-07-13
    Description: Theoretical models for X-ray burst sources that invoke thermonuclear flashes on the surface layers of an accreting neutron star are discussed. The historical development of X-ray burst observation is summarized, and a physical picture of a neutron star undergoing accretion is drawn. Detailed numerical computations of the evolution of the surface layers of such a star are reviewed. The need for general relativistic corrections to the model is pointed out. Finally, comparisons are made with observations of X-ray bursts, the rapid burster, fast X-ray transients, X-ray pulsars, and gamma-ray burst sources.
    Keywords: ASTROPHYSICS
    Type: Fundamental problems in the theory of stellar evolution; Jul 22, 1980 - Jul 25, 1980; Kyoto; Japan
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  • 68
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    Mass loss from interacting close binary systems (1981)
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    Publication Date: 2019-07-13
    Description: The three well-defined classes of evolved binary systems that show evidence of present and/or past mass loss are the cataclysmic variables, the Algols, and Wolf-Rayet stars. It is thought that the transformation of supergiant binary systems into the very short-period cataclysmic variables must have been a complex process. The new evidence that has recently been obtained from the far ultraviolet spectra that a certain subclass of the Algols (the Serpentids) are undergoing fairly rapid evolution is discussed. It is thought probable that the remarkable mass outflow observed in them is connected with a strong wind powered by accretion. The origin of the circumbinary clouds or flat disks that probably surround many strongly interacting binaries is not clear. Attention is also given to binary systems with hot white dwarf or subdwarf components, such as the symbiotic objects and the BQ stars; it is noted that in them both components may be prone to an enhanced stellar wind.
    Keywords: ASTROPHYSICS
    Type: Effects of mass loss on stellar evolution; Sep 15, 1980 - Sep 19, 1980; Trieste; Italy
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  • 69
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    Observations of stellar winds in early type stars (1981)
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    Publication Date: 2019-07-13
    Description: The presented review is mainly concerned with the massive population I stars of spectral type OB and the Wolf-Rayet (WR) class. It is pointed out that stellar winds are a ubiquitous phenomenon among the early type stars. Methods to determine the mass loss rate are discussed, taking into account the UV method, the optical method, the infrared method, and the radio method. Current beliefs about early type stars are considered. It is thought that all have stellar winds. The winds are primarily driven by radiation pressure from the UV lines, but other, as yet unknown factors, may determine the density and hence the rates. The stellar winds are highly ionized, more so than would be inferred from their continuum radiation temperatures. The ionization equilibrium in the winds is affected by local X rays which have been detected by the Einstein satellite. Unresolved issues are also pointed out.
    Keywords: ASTROPHYSICS
    Type: Effects of mass loss on stellar evolution; Sep 15, 1980 - Sep 19, 1980; Trieste; Italy
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  • 70
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    Theoretical models of X-ray emission from rich clusters of galaxies (1981)
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    Publication Date: 2019-07-13
    Description: After assessing the theory of cluster gas with polytropic equations of state, and discussing the prediction of local polytropic indices in the gas distribution, attention is given to the consequences of modifying the equation of state by thermal cooling in the central regions of the cluster. It is suggested that, if the equation of state can be understood locally, an attempt may be made at (1) predicting the X-ray luminosities of the clusters at distant cosmological epochs and (2) measuring the evolution of the cluster's potential, through observation of the evolution of X-ray luminosity and surface brightness.
    Keywords: ASTROPHYSICS
    Type: In: X-ray astronomy with the Einstein satellite; Jan 28, 1980 - Jan 30, 1980; Cambridge, MA
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  • 71
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    X-ray spectra of clusters of galaxies (1981)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Out of the many individual cases of clusters with spectral complexity reported in the literature, attention is given to the spectral complexity of the most recent data obtained by the Einstein Observatory and an attempt is made to explain at least a portion of the data in terms of models of radiatively-regulated accretion in the central parts of the clusters and/or onto massive galaxies. After a review of the range of models proposed, with emphasis on predicted temperature distribution, it is noted that all accretion models have temperatures which decrease toward the center, and that several authors have explored the consequences of radiative cooling of the gas in the dense central regions of a cluster or of a cluster plus a central galaxy.
    Keywords: ASTROPHYSICS
    Type: In: X-ray astronomy with the Einstein satellite; Jan 28, 1980 - Jan 30, 1980; Cambridge, MA
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  • 72
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    X-ray sources in globular clusters (1981)
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    Publication Date: 2019-07-13
    Description: The Einstein X-ray Observatory globular cluster observation program has completed a survey of 30 clusters, using the HRI detector. Preliminary results are reported for a more sensitive survey being conducted with the imaging proportional counter (IPC) of the satellite, which has found four possible new sources in the first 32 clusters observed. Also described are detailed studies of several luminous, globular cluster sources, including the X-ray burst from Terzan 2, and an effort is made to locate the X-ray sources with respect to cluster centers. Sources of systematic error, required optical studies of globular cluster structure, and the implications of the plausible binary systems for cluster core evolution are discussed.
    Keywords: ASTROPHYSICS
    Type: In: X-ray astronomy with the Einstein satellite; Jan 28, 1980 - Jan 30, 1980; Cambridge, MA
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  • 73
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    Outer atmospheres of late-type stars (1981)
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    Publication Date: 2019-07-13
    Description: Recent observational results concerning chromospheres and coronae in late-type stars are described. In particular, it is indicated where in the cool half of the HR diagram chromospheres, transition regions, coronae, and large mass loss occur and what the important parameters determining the energy balance of these layers are. The chromospheric modelling process is summarized and models of the late-type supergiants Beta Dra, Epsilon Gem, and Alpha Ori recently computed by Basri and Linsky (1980) are detailed.
    Keywords: ASTROPHYSICS
    Type: PB81-249021 , Physical processes in red giants; Sep 03, 1980 - Sep 13, 1980; Erice; Italy
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  • 74
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    Infrared sources in dense molecular clouds (1981)
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    Publication Date: 2019-07-13
    Description: Recent accomplishments in the infrared study of dense molecular clouds are reviewed, and the outstanding problems in the area are discussed. Such questions as whether clouds are collapsing, how they can be classified, and whether star formation is occurring on the edges of clouds are analyzed. Problems of determining size, energy distribution and luminosity, spectral features, evolutionary state, and energetics of infrared sources are discussed.
    Keywords: ASTROPHYSICS
    Type: Infrared astronomy; Jun 23, 1980 - Jun 27, 1980; Kona, HI
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  • 75
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    X-ray observations and the cosmic distance scale (1981)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: The physics of hot gas in the cores of distant clusters of galaxies can be studied in considerable detail through a specific combination of X-ray, microwave and optical observations. In principle, the X-ray luminosity of the gas can be calculated from these data, providing a measure of the cluster distance. These ideas and their application to Abell 2218, the only cluster for which even marginally suitable data yet exist are examined.
    Keywords: ASTROPHYSICS
    Type: In: X-ray astronomy with the Einstein satellite; Jan 28, 1980 - Jan 30, 1980; Cambridge, MA
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  • 76
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    Spectroscopy of compact extragalactic X-ray sources (1981)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: (Previously announced in STAR as N80-33332)
    Keywords: ASTROPHYSICS
    Type: In: X-ray astronomy with the Einstein satellite; Jan 28, 1980 - Jan 30, 1980; Cambridge, MA
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  • 77
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    The Einstein/CFA stellar survey - Overview of the data and interpretation of results (1981)
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    Publication Date: 2019-07-13
    Description: Results are presented from an extensive survey of stellar X-ray emission, using the Einstein Observatory. Over 140 stars have been detected to date, throughout the H-R diagram, thus showing that soft X-ray emission is the norm rather than the exception for stars in general. This finding is strongly at odds with pre-Einstein expectations based on standard acoustic theories of coronal heating. Typical examples of stellar X-ray detections and an overview of the survey data are presented. In combination with recent results from solar X-ray observations, the new Einstein data argue for the general applicability of magnetic field-related coronal heating mechanisms.
    Keywords: ASTROPHYSICS
    Type: In: X-ray astronomy with the Einstein satellite; Jan 28, 1980 - Jan 30, 1980; Cambridge, MA
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  • 78
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    Theory of stellar coronae - An interpretation of X-ray emission from non-degenerate stellar sources (1981)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: It is shown that the acoustic wave heating theory of stellar coronae explains neither Einstein Observatory coronae data nor previous UV and X-ray observations of the sun and other stars, on the evidence of data implying that magnetic fields, stellar rotation rates and convection zone parameters figure in the determination of coronal heating. Einstein Observatory results suggest that O-type star coronae are heated by the interaction of turbulent stellar winds with slowly-decaying primordial magnetic fields or by radiative instabilities in the flow. The apparent absence of coronae in Ap stars is due to the stability of atmospheres in which even weak convection is suppressed by the strong field. Dynamo action is implicated in some normal A-type stars and in F- and later-type dwarfs. Coronal characteristics of dMe and dM stars, close binaries, and K- and M-type giants are also considered.
    Keywords: ASTROPHYSICS
    Type: In: X-ray astronomy with the Einstein satellite; Jan 28, 1980 - Jan 30, 1980; Cambridge, MA
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  • 79
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    Tests of general relativity using Starprobe radio metric tracking data (1982)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: The potential of a proposed spacecraft mission, called Starprobe, for testing general relativity and providing information on the interior structure and dynamics of the sun is investigated. Parametric, gravitational perturbation terms are derived which represent relativistic effects and effects due to spatial and temporal variations in the solar potential at a given radial distance. A covariance analysis based on Kalman filtering theory predicts the accuracies with which the free parameters in the perturbation terms can be estimated with radio metric tracking data through the process of trajectory reconstruction. It is concluded that Starprobe can contribute significant information on both the nature of gravitation and the structure and dynamics of the solar interior.
    Keywords: ASTROPHYSICS
    Type: AIAA PAPER 82-0205 , Aerospace Sciences Meeting; Jan 11, 1982 - Jan 14, 1982; Orlando, FL
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  • 80
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    Nuclear and particle physics in the early universe (1981)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Basic principles and implications of Big Bang cosmology are reviewed, noting the physical evidence of a previous universe temperature of 10,000 K and theoretical arguments such as grand unification decoupling indicating a primal temperature of 10 to the 15th eV. The Planck time of 10 to the -43rd sec after the Big Bang is set as the limit before which gravity was quantized and nothing is known. Gauge theories of elementary particle physics are reviewed for successful predictions of similarity in weak and electromagnetic interactions and quantum chromodynamic predictions for strong interactions. The large number of photons in the universe relative to the baryons is considered and the grand unified theories are cited as showing the existence of baryon nonconservation as an explanation. Further attention is given to quark-hadron phase transition, the decoupling for the weak interaction and relic neutrinos, and Big Bang nucleosynthesis.
    Keywords: ASTROPHYSICS
    Type: Nuclear astrophysics; Mar 25, 1980 - Apr 06, 1980; Erice; Italy
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  • 81
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    The influence of co-rotating interaction regions on relativistic cosmic rays and geomagnetic activity (1981)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: It is established that the nucleonic intensity recorded at the polar stations Thule and McMurdo decreases as the streams associated with co-rotating interaction regions (CIR) overtake the earth. The modulation, however, is limited to only those CIR-streams in which a neutral sheet is imbedded. In contrast to this, all CIR-streams produce geomagnetic storms.
    Keywords: ASTROPHYSICS
    Type: International Cosmic Ray Conference; Jul 13, 1981 - Jul 25, 1981; Paris; France
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  • 82
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    Determination of magnetic helicity in the solar wind and implications for cosmic ray propagation (1981)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Magnetic helicity (Hm) is the mean value of the correlation between a turbulent magnetic field and the magnetic vector potential. A technique is described for determining Hm and its 'reduced' spectrum from the two point magnetic correlation matrix. The application of the derived formalism to solar wind magnetic fluctuations is discussed, taking into account cases for which only single point measurements are available. The application procedure employs the usual 'frozen in approximation' approach. The considered method is applied to an analysis of several periods of Voyager 2 interplanetary magnetometer data near 2.8 AU. During these periods the correlation length, or energy containing length, was found to be approximately 3 x 10 to the 11th cm
    Keywords: ASTROPHYSICS
    Type: International Cosmic Ray Conference; Jul 13, 1981 - Jul 25, 1981; Paris; France
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  • 83
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    The role of magnetic helicity in cosmic ray transport theory (1981)
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    Publication Date: 2019-07-13
    Description: It has been found that the computed values of the mean free path for pitch angle scattering of low rigidity cosmic rays computed from weak turbulence theory are systematically larger than the values inferred from analyses of solar particle events. Reasons for this discrepancy are considered, taking into account components of the spectral tensor of the magnetic field fluctuations which can contribute to pitch angle scattering. The contributions of the additional terms can be estimated from the interplanetary magnetic field. It is shown that these additional contributions can be significant. A description is given of a formalism which includes the possibility that the field magnitude is constant. The formalism provides a formal basis for the heuristic arguments made by Goldstein (1980).
    Keywords: ASTROPHYSICS
    Type: International Cosmic Ray Conference; Jul 13, 1981 - Jul 25, 1981; Paris; France
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  • 84
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    Origins of the low energy relativistic interplanetary electrons (1981)
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    Publication Date: 2019-07-13
    Description: Electron measurements in the energy range 2-25 MeV on the Pioneer 10 spacecraft are studied from 1 to 21.5 AU. It is found that in this radial range, interplanetary low energy electron fluxes are of Jovian origin, based on the decreasing electron intensity from about 6 to 21.5 AU, a negative gradient from about 11 to 21.5 AU, and the constant spectral index observed from 1 to 21.5 AU. The upper limit of the galactic flux is estimated at 12 MeV and standard assumptions are applied to solar modulation. It is found that at 1 AU, the expected flux of galactic origin is a factor 300 or more below the observed quiet time flux, and the extrapolated interstellar flux level is consistent with estimates based on galactic diffuse radio and gamma-ray emissions.
    Keywords: ASTROPHYSICS
    Type: International Cosmic Ray Conference; Jul 13, 1981 - Jul 25, 1981; Paris; France
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  • 85
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    Observations of interplanetary energetic charged particles from gamma-ray line solar flares (1981)
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    Publication Date: 2019-07-13
    Description: Results from ISEE-3 experiments on interplanetary energetic charged particles on June 7, June 21, and July 1, 1980 dealing with gamma ray producing solar flares are reported. The data were gathered by the Ultra Low Energy Wide Angle Telescope, which comprises a thin window, flow through proportional counter/solid-state detector composition telescope. Evidence of a specified time delay from an observed flare and the recording of 0.44-1.3 MeV electrons on ISEE-3 combined with quiescent periods of at least two hours before the observations and recording provides a link between the events. The data indicates interplanetary energetic particle enhancement, and a second, similar set of occurrences was also observed. Protons were accelerated up to 10-20 MeV. No enrichment of either He-3 or Fe was found.
    Keywords: ASTROPHYSICS
    Type: International Cosmic Ray Conference; Jul 13, 1981 - Jul 25, 1981; Paris; France
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  • 86
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    Interplanetary particle observations associated with solar flare gamma-ray line emission (1981)
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    Publication Date: 2019-07-13
    Description: Observations of particle emissions during three solar flares which were observed to emit 2.22 MeV gamma rays as recorded by the Solar Maximum Mission are discussed. The 2.22 MeV line is produced by neutron capture by hydrogen, and additional attention is given to a 4.4 MeV emission line of June 7, 1980, with estimates made of the particle density 1 AU from the sun assuming a good magnetic connection between the earth and the sun. The measurements were made from the ISEE-3 and HELIOS-1 spacecraft. The connectedness of the earth and the sun in a magnetic field leads to conclusions that few particles actually escaped into interplanetary space.
    Keywords: ASTROPHYSICS
    Type: International Cosmic Ray Conference; Jul 13, 1981 - Jul 25, 1981; Paris; France
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  • 87
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    Precursor active galaxies, active galaxies and the X-ray and gamma-ray background (1981)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: A description is presented of a model in which the X-ray and gamma-ray background can result from the superposition of radiation from active galaxies in different stages of their evolutionary history. This scheme is based on the generalization of a black-hole model developed for gamma-ray production in active galaxies by Leiter (1980). Both thermal and nonthermal accretion disk processes around massive rotating Kerr black holes are considered. Attention is given to cosmological conditions leading to precursor active galaxies (PAG), PAG as origin of the cosmic X-ray background, and the evolution of PAG into Seyfert galaxies as origin of the gamma-ray background. It is found that after spin-up of the central black hole an active galactic nucleus can generate nonthermal radiation very efficiently up to a few MeV.
    Keywords: ASTROPHYSICS
    Type: International Cosmic Ray Conference; Jul 13, 1981 - Jul 25, 1981; Paris; France
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  • 88
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    A high resolution measurement of hard X-ray features in the spectrum of Hercules X-1 (1981)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Keywords: ASTROPHYSICS
    Type: International Cosmic Ray Conference; Jul 13, 1981 - Jul 25, 1981; Paris; France
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  • 89
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    Scaling from Jupiter to pulsar and the acceleration of cosmic ray particles by pulsars (1981)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: The total energy output per second from the 73 known pulsars is estimated. By following the principle of similitude (Rayleigh, 1915), an expression is derived for the energy generated by a rotating magnetized celestial body, and the dipole moment of the body is related linearly with its angular momentum. The scaling constant of the two equations combined is determined, and then checked by comparing the deduced masses of the 73 pulsars with the theoretical limits for neutron stars. By using the scaling constant and deduced pulsar masses, the rates of acceleration of high-energy particles by pulsars, thence the energy output from pulsars, can be estimated. Results show that the Crab pulsar outshines all the others combined.
    Keywords: ASTROPHYSICS
    Type: International Cosmic Ray Conference; Jul 13, 1981 - Jul 25, 1981; Paris; France
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  • 90
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    Solar-ion penetration in the early solar nebula (1980)
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    Publication Date: 2019-07-13
    Description: A model for the early solar nebula is presented, along with the use of available ion range-energy relationships to determine when the irradiation of meteoritic grains occurred. Ions are assumed to travel on rectilinear paths with an energy change due solely to passage through absorbing materials, and consideration is given to the chances of energetic ions penetrating the nebular cloud to a distance of 3 AU. Cases of no absorbing gas, no absorbing dust, and the presence of both gas and dust are discussed, and model calculations are presented for protons and Fe nuclei ions. Penetration is found to decrease with the increase of the total amount of dust, a step function results when the size of the particles decreases, a fixed dust mass yields a penetration probability tending toward zero as the radius of the particles decreases, the fraction of the total dust mass required for penetration at 3 AU is small, and penetration to 3 AU readily occurs under present conditions.
    Keywords: ASTROPHYSICS
    Type: Lunar and Planetary Science Conference; Mar 17, 1980 - Mar 21, 1980; Houston, TX
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  • 91
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    Interplanetary dust collected in the earth's stratosphere - The question of solar flare tracks (1980)
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    Publication Date: 2019-07-13
    Description: The negative result of a transmission electron microscope (TEM) search for solar flare tracks in 10 micron interplanetary dust particles (Flynn et al., 1978) which have been collected in the earth's stratosphere with a program of sampling initiated by Brownlee et al. (1976) has been reported previously. In this paper, it is shown that silicates in the particles record laboratory iron-ion tracks which are detectable in the TEM. The absence of tracks in the silicates could be due to track annealing on atmospheric entry, and may indicate a particle emissivity below 0.3, or that many of the particles broke up on encounter with the atmosphere. Alternatively, the lifetime of 10 micron dust particles at 1 AU could be shorter than that given by previous estimates.
    Keywords: ASTROPHYSICS
    Type: Lunar and Planetary Science Conference; Mar 17, 1980 - Mar 21, 1980; Houston, TX
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  • 92
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    Molecules in interstellar clouds (1981)
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    Publication Date: 2019-07-13
    Description: The physical conditions and chemical compositions of the gas in interstellar clouds are reviewed in light of the importance of interstellar clouds for star formation and the origin of life. The Orion A region is discussed as an example of a giant molecular cloud where massive stars are being formed, and it is pointed out that conditions in the core of the cloud, with a kinetic temperature of about 75 K and a density of 100,000-1,000,000 molecules/cu cm, may support gas phase ion-molecule chemistry. The Taurus Molecular Clouds are then considered as examples of cold, dark, relatively dense interstellar clouds which may be the birthplaces of solar-type stars and which have been found to contain the heaviest interstellar molecules yet discovered. The molecular species identified in each of these regions are tabulated, including such building blocks of biological monomers as H2O, NH3, H2CO, CO, H2S, CH3CN and H2, and more complex species such as HCOOCH3 and CH3CH2CN.
    Keywords: ASTROPHYSICS
    Type: Origin of life; Jun 22, 1980 - Jun 27, 1980; Jerusalem; Israel
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  • 93
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    Ultraviolet spectroscopy of comets (1981)
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    Publication Date: 2019-07-13
    Description: Results of observations of comets in the ultraviolet are reviewed in relation to their significance for the chemistry and physics of the cometary coma and the composition of the cometary ice. Ultraviolet cometary observations began in 1970, when a hydrogen envelope was discovered extending millions of kilometers from the nucleus of comet Bennett, and continued with the discovery of oxygen and carbon in comet Kohoutek and the acquisition of comprehensive UV spectra from comets West (1976 VI), Seargent (1978 XV) and Bradfield (1979 X). The available cometary spectra are remarkably similar, indicative of a common composition and origin for comets and the insignificance of chemical reactions in the inner coma to species abundances. Ultraviolet spectroscopy has also allowed the determination of gas production rates from either the surface brightness or the total luminosity in a given spectral line. IUE observations of comet Bradfield reveal the water production rate to vary as the -3.7 power of heliocentric distance from 0.71 to 1.55 AU, incompatible with solar energy input as the controlling influence on water vaporization.
    Keywords: ASTROPHYSICS
    Type: Comets and the origin of life; Oct 29, 1980 - Oct 31, 1980; College Park, MD
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  • 94
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    Light scattering calculations for the nephelometer experiment on the 1981/1982 Jupiter Orbiter-Probe mission (1982)
    In:  CASI
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    Publication Date: 2019-07-13
    Description: A variety of studies were carried out to help establish the accuracy of quantities describing physical characteristics of cloud particles (such as size, shape, and composition) that are to be inferred from light scattering data obtained with the nephelameter experiment on the Galileo spacecraft. The objectives were to provide data for validating and testing procedures for analyzing the Galileo nephelameter data with light scattering observations in a variety of on-going laboratory and field measurement programs for which simultaneous observations of the physical characteristics of the scattering particles were available.
    Keywords: ASTROPHYSICS
    Type: NASA-CR-169418 , NAS 1.26:169418
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  • 95
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    Fundamental studies in X-ray astrophysics (1982)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: An analytical model calculation of the ionization structure of matter accreting onto a degenerate dwarf was carried out. Self-consistent values of the various parameters are used. The possibility of nuclear burning of the accreting matter is included. We find the blackbody radiation emitted from the stellar surface keeps hydrogen and helium ionized out to distances much larger than a typical binary separation. Except for low mass stars or high accretion rates, the assumption of complete ionization of the elements heavier than helium is a good first approximation. For low mass stars or high accretion rates the validity of assuming complete ionization depends sensitivity on the distribution of matter in the binary system.
    Keywords: ASTROPHYSICS
    Type: NASA-CR-168840 , NAS 1.26:168840 , PR-1
    Format: application/pdf
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  • 96
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    Energetic particles flux experiment for ISEE mother/daughter spacecraft (1981)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The history of the energetic particle experiments on the International Sun Earth Explorer 1 and 2 spacecraft is outlined, and descriptions of the instruments are given. The inflight performance and data analysis are summarized. The research is completed and ongoing are described and a bibliography is included.
    Keywords: ASTROPHYSICS
    Type: NASA-CR-166761
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  • 97
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    A new view of Baryon symmetric cosmology based on grand unified theories (1981)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Within the framework of grand unified theories, it is shown how spontaneous CP violation leads to a domain structure in the universe with the domains evolving into separate regions of matter and antimatter excesses. Subsequent to exponential horizon growth, this can result in a universe of matter galaxies and antimatter galaxies. Various astrophysical data appear to favor this form of big bang cosmology. Future direct tests for cosmologically significant antimatter are discussed.
    Keywords: ASTROPHYSICS
    Type: NASA-TM-83828 , Oxford Intern. Symp. on Progress in Cosmology,; Sep 01, 1981; Oxford
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  • 98
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    Evidence for ice meteoroids beyond 2 AU (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Processes controlling the population of particles of mass greater than 2 x 10 to the -9th g as observed by the Pioneer 10 meteoroid penetration data between 2 and 5 AU are discussed as evidence for the presence of ice meteoroids. Consideration is given to particle collisional lifetimes, Poynting-Robertson drag and the influence of Jupiter in controlling particle orbits, and it is noted that none of these mechanisms may be capable of accounting for the observed constant, or possibly increasing, particle density between 2 and 5 AU. It is shown, however, that ice particles with radii of about 15 microns and varying amounts of impurities could account for the observed distribution with thermal sublimation or solar wind sputtering possible mechanisms of particle destruction. It is concluded that meteoroids made of ice are probably responsible for most of the penetrations of the Pioneer 10 meteoroid penetration sensor beyond 2 AU.
    Keywords: ASTROPHYSICS
    Type: Symposium on Solid particles in the solar system; Aug 27, 1979 - Aug 30, 1979; Ottawa; Canada
    Format: text
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  • 99
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    Analysis of interplanetary dust collections (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Interplanetary dust particles collected in the form of micrometeorites in the stratosphere and meteor ablation spherules in deep sea sediments are possibly a relatively unbiased sample of the micrometeoroid complex near 1 AU. Detailed laboratory analysis of the particles has provided information on physical properties which may be useful in modeling a variety of aspects of interplanetary dust.
    Keywords: ASTROPHYSICS
    Type: Symposium on Solid particles in the solar system; Aug 27, 1979 - Aug 30, 1979; Ottawa; Canada
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  • 100
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    On the particle-size distribution function of cometary dust (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The characterization of the particle size distribution in cometary tails is considered. The particle-size related distribution function of the acceleration exerted on the cometary particle by solar radiation pressure used by Finson and Probstein (1968) is introduced, and distribution functions observed for the comets Arend-Roland 1957 III, Bennett 1970 II and Seki-Lines 1962 III are illustrated. It is pointed out that although the distribution functions have features in common, the rate of decrease of the distribution towards zero acceleration (large particles) is not well determined. An approximation for the size distribution in this range obtained from a photometric study of anomalous cometary tails is presented, and used to formulate an a priori distribution law which can be used to approximate all types of expected distributions by varying three key parameters.
    Keywords: ASTROPHYSICS
    Type: Symposium on Solid particles in the solar system; Aug 27, 1979 - Aug 30, 1979; Ottawa; Canada
    Format: text
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