Showing papers in "Annual Review of Astronomy and Astrophysics in 1986"
TL;DR: The modern study of supernovae involves many aspects: presupernova stellar evolution, the physics of the explosions themselves, observations at all wavelengths of the outbursts and their remnants, nuc1eosynthesis and the chemical evolution of galaxies, interaction with the interstellar medium, cosmic-ray acceleration, supernova as distance indicators, and other potentially observable phenomena such as neutrino bursts, gravitational radiation, and the emissions of a white dwarf collapsing directly to a neutron star as mentioned in this paper.
Abstract: The modern study of supernovae involves many aspects: presupernova stellar evolution, the physics of the explosions themselves, observations at all wavelengths of the outbursts and their remnants, nuc1eosynthesis and the chemical evolution of galaxies, interaction with the interstellar medium, cosmic-ray acceleration, supernovae as distance indicators, and other potentially observable phenomena such as neutrino bursts, gravitational radiation, and the emissions of a white dwarf collapsing directly to a neutron star. In this review, although touching on a number of these topics, we are chiefly concerned with the physical processes currently held responsible for the explosion and radiation of Type I and II supernovae and the observable diagnostics of the models: energetics, nucleosynthesis, light curves, and spectra. Discussions of a broader nature appear elsewhere (Trimble 1982, 1983, Rees & Stoneham 1982, Branch 1986a, Helfand & Becker 1984). Here, if for no reasons other than space limitations, we focus on recent developments in our theoretical understanding of how supernovae work, especially insight achieved during the last very fruitful decade (see also Arnett 1978a, Sugimoto & Nomoto 1980, Wheeler 198 1 , 1 982, Weaver & Woosley 1 980a, Woosley & Weaver 1 98 1 , Chevalier 198 1 a, Brown et al. 1982, Imshennik & Nadezhin 1983, Hillebrandt 1984, Nomoto 1 985a, Bethe & Brown 1985), and, perhaps at the expense of
668 citations
TL;DR: In this paper, the authors focus on the amount and nature of information about the image present in the measurements, which has become increasingly relevant with the growth of interferometry, where the data correspond to the Fourier transform of the image.
Abstract: Imaging the two-dimensional intensity distribution of the sky has always been an important part of astronomy. This is particularly true at present, a time when aperture synthesis mapping is firmly established in radio astronomy, charge-coupled devices are revolutionizing optical imaging, and X-ray-imaging cameras are being flown in space. Atmospheric irregularities, instrument aberrations, detector noise, and the diffraction limit all cause the observed image to deviate from the ideal one. Image restoration techniques have therefore had a long history. The field owes much to the classic papers of Bracewell & Roberts ( 12) and Fellgett & Linfoot (35), which focused attention on the amount and nature of information about the image present in the measurements. These ideas have become increasingly relevant with the growth of interferometry, where the data correspond to the Fourier transform of the image. The Michelson stellar interferometer (82) was an early application in optical astronomy. However, it is at radio frequencies where interferometry has proved most fruitful and where astronomers have had to face the problem
405 citations
TL;DR: In this paper, the authors describe the evolution of massive etoiles in the diagramme HR d'etoiles lumineuses with perte-de-menance.
Abstract: Evolution a masse constante. Diagnostic de vents stellaires et parametrisation des taux de perte de masse. Effets de perte de masse sur la structure interne et l'evolution des etoiles massives. Effets de perte de masse sur le diagramme HR d'etoiles lumineuses. Evolution avec depeuplement convectif et perte de masse. Nucleosynthese. Nature des etoiles type Wolf Rayet. Distribution galactique de supergeantes O, bleues et rouges et d'etoiles type WR
365 citations
TL;DR: In this article, the star counts provided bounds for the luminosity function and the color-magnitude diagram and allowed spheroid normalization in a copycat Galaxy model which posits a galaxy with a Population I disk and a Population II spheroroid.
Abstract: Star counts are discussed as an aid in studies of galactic structure. Iterative computations using a method-of-color-bins to match numerical models with observational data are described. The star counts provide bounds for the luminosity function and the color-magnitude diagram and allow spheroid normalization in a copycat Galaxy model which posits a galaxy with a Population I disk and a Population II spheroid. Good agreement has been obtained between star counts predicted by the model and observed distributions, including color and magnitude ranges and direction. Modifications being considered for the model include consideration of the halo, a galactic bulge and a thick disk. Several galactic structural features which have yet to be modeled and which may be tractable to the copycat model corrected with star counts are identified.
197 citations
TL;DR: In this article, the configuration du champ and its implications on the dynamique, evolution, and activite dans galaxies spirales are discussed, as well as les techniques d'observations, les donnees, les methods, and les methods used for obtenir the configuration of the champ dans the galaxies.
Abstract: On presente les techniques d'observations, les donnees d'observations courantes et les methodes utilisees pour obtenir la configuration du champ dans les galaxies spirales. On discute de la configuration du champ et de ses implications sur la dynamique, l'evolution et l'activite dans les galaxies spirales
171 citations
TL;DR: In this article, a discussion de la theorie "classique" de l'evolution des regions H II, on presente les resultats d'etudes recentes de la nature non classique.
Abstract: L'introduction presente les relations avec l'evolution stellaire et la structure du milieu interstellaire. On presente ensuite les equations a resoudre et les approximations possibles. Apres une discussion de la theorie «classique» de l'evolution des regions H II, on presente les resultats d'etudes recentes de la nature non classique. On compare la theorie aux resultats d'observations
144 citations
TL;DR: In this article, relativistic corrections are defined for adjusting for differences between the pulsar motion in its spacetime coordinate system relative to the terrestrial coordinate system, the earth's motion, and the gravitational potentials of solar system bodies.
Abstract: Techniques are described for accounting for relativistic effects in the analysis of pulsar signals. Design features of instrumentation used to achieve millisecond accuracy in the signal measurements are discussed. The accuracy of the data permits modeling the pulsar physical characteristics from the natural glitches in the emissions. Relativistic corrections are defined for adjusting for differences between the pulsar motion in its spacetime coordinate system relative to the terrestrial coordinate system, the earth's motion, and the gravitational potentials of solar system bodies. Modifications of the model to allow for a binary pulsar system are outlined, including treatment of the system as a point mass. Finally, a quadrupole model is presented for gravitational radiation and techniques are defined for using pulsars in the search for gravitational waves.
135 citations
TL;DR: In this article, the authors summarized recent progress in the characterization of the interstellar medium (ISM) by means of optical and UV spectral data, focusing on background stars whose spectra can be accurately modeled to provide the light source for the absorption-line scans.
Abstract: Recent progress in the characterization of the interstellar medium (ISM) by means of optical and UV spectral data is summarized. The gas is studied by focusing on background stars whose spectra can be accurately modeled to provide the light source for the absorption-line scans. The capabilities of earth- and space-based instruments which have been and are used for the surveys are delineated. The distributions of diffuse gas densities and characteristics of the cold, warm and hot gas in the Galaxy are described in terms of the elemental abundances, kinetics and distributions of the gas. Particular note is taken of gas in the solar neighborhood and around SNR, and of absorption-line data of cosmological significance.
122 citations
TL;DR: In this article, les donnees d'observations concerned with the structure and le champ des vitesses du gaz ionise contenu dans les noyaux galactiques actifs.
Abstract: On presente les donnees d'observations qui concernent la structure et le champ des vitesses du gaz ionise contenu dans les noyaux galactiques actifs. On examine deux interpretations theoriques pour la region a raies larges puis on presente plusieurs modeles theoriques recents concernant la region a raies etroites
122 citations
TL;DR: In this paper, a general picture of mass loss from cool stars is developed and related to chromospheric and coronal emissions measured by IUE and the HEAO-2 Obgervatory.
Abstract: Recently obtained spectroscopic observations indicating mass loss in cool stars are reviewed with analogies to the solar atmosphere. Spectral diagnostics of mass loss are discussed with new theoretical calculations of chromospheric line profiles. A general picture of mass loss from cool stars is developed and related to chromospheric and coronal emissions measured by IUE and the HEAO-2 Obgervatory. These winds range in characteristics from the hot (106 K) and fast wind with low mass loss found in the dwarf stars to the warm (~ 10-5 K), moderate speed winds present in hybrid luminous supergiants, and the coolest massive winds emerging from the latest type supergiants exhibiting lowest thermal velocities and circumstellar shells. Evidence for stellar surface inhomogeneity and variability of outflow is briefly discussed.
95 citations
TL;DR: Evolution de la recherche sur les pulsars durant les 18 dernieres annees is described in this article, where the evolution of the pulsars is discussed.
Abstract: Evolution de la recherche sur les pulsars durant les 18 dernieres annees. Connaissances actuelles
TL;DR: In this paper, the authors present le developpements historiques du concept de population and s'interroge sur l'impact qu'a eu ce concept, sur la comprehension du diagramme HR en tant qu'outil permettant de cartographier la galaxie, couche par couche, en fonction de l'âge.
Abstract: Dans une premiere partie, on presente les developpements historiques du concept de population. Dans la seconde partie, on s'interroge sur l'impact qu'a eu ce concept, sur la comprehension du diagramme HR en tant qu'outil permettant de cartographier la galaxie, couche par couche, en fonction de l'âge. L'idee dominante est ici la correlation des mouvements spaciaux avec [Fe/H] pour les divers sous-groupes de population dans le diagramme HR
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TL;DR: Thermochimie dans les atmospheres stellaires, abondance et proprietes des molecules observees. Opacite moleculaire et structures atmospheriques as discussed by the authors.
Abstract: Thermochimie dans les atmospheres stellaires, abondance et proprietes des molecules observees. Opacite moleculaire et structures atmospheriques
TL;DR: In this article, the authors summarized the results of recent studies (in the UV) of the structure and dynamics of the quiet solar transition region and its role in the mass and energy balance of the outer layers of the solar atmosphere.
Abstract: The results of recent studies (in the UV) of the structure and dynamics of the quiet solar transition region and its role in the mass and energy balance of the outer layers of the solar atmosphere are summarized. The region is one in which temperature increases from 25,000 K to about 1 million K and the matter density, fed by the outward flowing wind and the inward streaming plasma, increases by a factor of 40. The morphology of the region is described, along with the theoretical models being applied to the observed nonthermal line broadening, Doppler wavelength shifts, temporal fluctuations, and fine structure. Deficiencies in existing simple models of the region are discussed.