Advanced Stages Of Stellar Evolution Research Articles

First 3D radiation-hydrodynamic simulations of Wolf-Rayet winds

Context. Classical Wolf-Rayet (WR) stars are direct supernova progenitors undergoing vigorous mass loss. Understanding the dense and fast outflows of such WR stars is thus crucial for understanding advanced stages of stellar evolution and the dynamical feedback of massive stars on their environments, and for characterizing the distribution of black hole masses. Aims. In this paper, we develop the first time-dependent, multidimensional, radiation-hydrodynamical models of the extended optically thick atmospheres and wind outflows of hydrogen-free classical WR stars. Methods. A flux-limiting radiation hydrodynamics approach is used on a finite volume mesh to model WR outflows. The opacities are described using a combination of tabulated Rosseland mean opacities and the enhanced line opacities expected within a supersonic flow. Results. For high-luminosity models, a radiation-driven, dense, supersonic wind is launched from deep subsurface regions associated with peaks in the Rosseland mean opacity. For a model with lower luminosity, on the other hand, the Rosseland mean opacity is not sufficient to sustain a net-radial outflow in the subsurface regions. Instead, what develops in this case, is a "standard" line-driven wind launched from the optically thin regions above an extended, moderately inflated, and highly turbulent atmosphere. We thus find here a natural transition from optically thick outflows of classical WR stars to optically thin winds of hot, compact subdwarfs; in our simulations, this transition occurs approximately at a luminosity that is ~40% of the Eddington luminosity. Because of the changing character of the wind-launching mechanism, this transition is also accompanied by a large drop (on the low-luminosity end) in the average mass-loss rate. Since the subsurface opacity peaks are further associated with convective instabilities, the flows are highly structured and turbulent, consisting of coexisting regions of outflowing, stagnated, and even pockets of infalling gas. Typical velocity dispersions in our 3D models are high, 100–300 km s−1, but the clumping factors are rather modest, fc1 ≡ 〈ρ2〉/〈ρ〉2 ~ 2. We further find that, while the low-density gas in our simulations is strongly radiation-driven, the overdense structures are, after their initial launch, primarily advected outward by ram-pressure gradients. This inefficient radiative acceleration of dense "clumps" reflects the inverse dependence of line driving on mass density and leads to a general picture wherein high-density gas parcels move significantly slower than the mean and low-density wind material.

Seismic constraints on the internal structure of evolved stars: From high-luminosity RGB to AGB stars

Context. The space-borne missions CoRoT and Kepler opened up a new opportunity for better understanding stellar evolution by probing stellar interiors with unrivalled high-precision photometric data. Kepler has observed stellar oscillation for four years, which gave access to excellent frequency resolution that enables deciphering the oscillation spectrum of evolved red giant branch and asymptotic giant branch stars. Aims. The internal structure of stars in the upper parts of the red and asymptotic giant branches is poorly constrained, which makes the distinction between red and asymptotic giants difficult. We perform a thorough seismic analysis to address the physical conditions inside these stars and to distinguish them. Methods. We took advantage of what we have learnt from less evolved stars. We studied the oscillation mode properties of ∼2.000 evolved giants in a model described by the asymptotic pressure-mode pattern of red giants, which includes the signature of the helium second-ionisation zone. Mode identification was performed with a maximum cross-correlation method. Then, the modes were fitted with Lorentzian functions following a maximum likelihood estimator technique. Results. We derive a large set of seismic parameters of evolved red and asymptotic giants. We extracted the mode properties up to the degree ℓ = 3 and investigated their dependence on stellar mass, metallicity, and evolutionary status. We identify a clear difference in the signature of the helium second-ionisation zone between red and asymptotic giants. We also detect a clear shortage of the energy of ℓ = 1 modes after the core-He-burning phase. Furthermore, we note that the mode damping observed on the asymptotic giant branch is similar to that observed on the red giant branch. Conclusions. We highlight that the signature of the helium second-ionisation zone varies with stellar evolution. This provides us with a physical basis for distinguishing red giant branch stars from asymptotic giants. Here, our investigation of stellar oscillations allows us to constrain the physical processes and the key events that occur during the advanced stages of stellar evolution, with emphasis on the ascent along the asymptotic giant branch, including the asymptotic giant branch bump.

Testing tidal theory for evolved stars by using red giant binaries observed by Kepler

Abstract Tidal interaction governs the redistribution of angular momentum in close binary stars and planetary systems and determines the systems evolution towards the possible equilibrium state. Turbulent friction acting on the equilibrium tide in the convective envelope of low-mass stars is known to have a strong impact on this exchange of angular momentum in binaries. Moreover, theoretical modelling in recent literature as well as presented in this paper suggests that the dissipation of the dynamical tide, constituted of tidal inertial waves propagating in the convective envelope, is weak compared to the dissipation of the equilibrium tide during the red giant phase. This prediction is confirmed when we apply the equilibrium-tide formalism developed by Zahn, Verbunt & Phinney, and Remus, Mathis & Zahn on to the sample of all known red giant binaries observed by the NASA Kepler mission. Moreover, the observations are adequately explained by only invoking the equilibrium tide dissipation. Such ensemble analysis also benefits from the seismic characterization of the oscillating components and surface rotation rates. Through asteroseismology, previous claims of the eccentricity as an evolutionary state diagnostic are discarded. This result is important for our understanding of the evolution of multiple star and planetary systems during advanced stages of stellar evolution.

Posters also presented at the Symposium

I am reporting on our team's progress in investigating fundamental properties of convective shells in the deep stellar interior during advanced stages of stellar evolution. We have performed a series of 3D hydrodynamic simulations of convection in conditions similar to those in the O-shell burning phase of massive stars. We focus on characterizing the convective boundary and the mixing of material across this boundary. Results from 7683 and 15363 grids are encouragingly similar (typically within 20%). Several global quantities, including the rate of mass entrainment at the convective boundary and the driving luminosity, are related by scaling laws. We investigate the effect of several of our assumptions, including the treatment of the nuclear burning driving the convection or that of neutrino cooling. The burning of the entrained material from above the convection zone could have important implications for pre-supernova nucleosynthesis.

THE PROPAGATION OF UNCERTAINTIES IN STELLAR POPULATION SYNTHESIS MODELING. II. THE CHALLENGE OF COMPARING GALAXY EVOLUTION MODELS TO OBSERVATIONS

Models for the formation and evolution of galaxies readily predict physical properties such as the star formation rates, metal enrichment histories, and, increasingly, gas and dust content of synthetic galaxies. Such predictions are frequently compared to the spectral energy distributions of observed galaxies via the stellar population synthesis (SPS) technique. Substantial uncertainties in SPS exist, and yet their relevance to the task of comparing galaxy evolution models to observations has received little attention. In the present work we begin to address this issue by investigating the importance of uncertainties in stellar evolution, the initial stellar mass function (IMF), and dust and interstellar medium (ISM) properties on the translation from models to observations. We demonstrate that these uncertainties translate into substantial uncertainties in the ultraviolet, optical, and near-infrared colors of synthetic galaxies. Aspects that carry significant uncertainties include the logarithmic slope of the IMF above 1 Msun, dust attenuation law, molecular cloud disruption timescale, clumpiness of the ISM, fraction of unobscured starlight, and treatment of advanced stages of stellar evolution including blue stragglers, the horizontal branch, and the thermally-pulsating asymptotic giant branch. The interpretation of the resulting uncertainties in the derived colors is highly non-trivial because many of the uncertainties are likely systematic, and possibly correlated with the physical properties of galaxies. We therefore urge caution when comparing models to observations.

BINARY ORBIT, PHYSICAL PROPERTIES, AND EVOLUTIONARY STATE OF CAPELLA (α AURIGAE)

We report extensive radial velocity measurements of the two giant components of the detached, 104 day period binary system of Capella. Our highly accurate three-dimensional orbital solution based on all existing spectroscopic and astrometric observations including our own yields much improved masses for the primary and secondary of 2.466 {+-} 0.018 M {sub sun} and 2.443 {+-} 0.013 M {sub sun}, with relative errors of only 0.7% and 0.5%, respectively. The mass ratio is considerably closer to unity than previously believed, which has an impact on assessing the evolutionary state of the system. Improved values are presented also for the radii (11.87 {+-} 0.56 R {sub sun} and 8.75 {+-} 0.32 R {sub sun}), effective temperatures (4920 {+-} 70 K and 5680 {+-} 70 K), and luminosities (79.5 {+-} 4.8 L {sub sun} and 72.1 {+-} 3.6 L {sub sun}). The distance is determined to be 13.042 {+-} 0.028 pc, based on the accurate orbital parallax. The projected rotational velocities and individual rotation periods are also known. Capella is unique among evolved stars in that, in addition to all of the above, the chemical composition is known as well. This includes the overall metallicity [m/H], the carbon isotope ratio {supmore » 12}C/{sup 13}C for the primary, and the lithium abundance and C-to-N ratios for both components. We present new or revised values for some of these. The latter three quantities are sensitive diagnostics of evolution, and change drastically for giants as a result of the deepening of the convective envelope during the first dredge-up. The secondary is crossing the Hertzprung gap, while the primary is believed to be in the longer-lived core helium-burning phase. Previous studies using only the masses, temperatures, and luminosities have found good agreement with stellar evolution models placing the primary in the clump. Here, we compare all of the constraints simultaneously against three sets of current models. We find that they are unable to match all of the observations for both components at the same time, and at a single age, for any evolutionary state of the primary. This shows the great importance of chemical information for assessing the evolutionary state of giant stars. A comparison with models of tidal evolution yields similarly disappointing results, when tested against the fact that the orbit is circular, the primary is rotating synchronously, the secondary {approx}12 times faster than synchronous, and the spin axes are apparently aligned with the axis of the orbit. When confronted in detail, our understanding of the advanced stages of stellar evolution is thus still very incomplete.« less

Asteroseismology of white dwarf and sdB stars

A brief description of the various types of variable stars occuring in the advanced stages of stellar evolution is given. This includes the Planetary Nebulae Nuclei variables (PNNV), the PG 1159 variables, the sdB pulsators and the DB and DA white dwarf pulsators. In this review, the emphasis is put on the importance of diffusion for either the excitation mechanism or the properties of the oscillations.

Ernst Öpik's fundamental ideas on the structure of red giants

As early as in 1923, the Estonian astronomer Ernst Opik indicated in a pioneering investigation that the only source of stellar radiative energy capable of sustaining the observed stellar luminosities for billions of years must be the process of nuclear fusion in stellar cores, transforming hydrogen into helium, carbon and so forth up to iron. He was the first to introduce in 1938 the so-called compound unmixed stellar models with a helium stellar convective core and a hydrogen envelope in radiative equilibrium lying on the top of it. Contrary to the universally adopted view of Eddington who firmly believed that rotationally induced convection would inevitably lead to a full mixing of the stellar matter, calculations of Opik confirmed the validity of compound models and indicated that upon the exhaustion of hydrogen the core will start contracting whereas the hydrogen envelope will expand. The structural differences between giant and main sequence stars were interpreted in this way, and stellar evolution along the H-R diagram explained in broad features. Opik was ahead of Fred Hoyle and Martin Schwarzschild who reached similar conclusions only 15 years later. Here we analyze various implications of Opik's research dedicated to the internal structure of red giants for the treatment of the advanced stages of stellar evolution. It took almost half a century before the priority of this discovery by the Estonian astrophysicist found a deserved recognition.

Multielectron SEFs for nuclear reactions involved in advanced stages of stellar evolution

Multielectron screening effects encountered in laboratory astrophysical reactions are investigated by considering the reactants Thomas–Fermi atoms. By means of that model, previous studies are extended to derive the corresponding screening enhancement factor (SEF), so that it takes into account ionization, thermal, exchange and relativistic effects. The present study, by imposing a very satisfactory constraint on the possible values of the screening energies and the respective SEFs, corrects the current (and the future) experimental values of the astrophysical factors associated with nuclear reactions involved in advanced stages of stellar evolution.

Solar neutrinos: Sensitivity to pre-main-sequence evolution and to the depth of the convective zone

view Abstract Citations (10) References (24) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Solar Neutrinos: Sensitivity to Pre--Main-Sequence Evolution and to the Depth of the Convective Zone Bahcall, John N. ; Glasner, Ami Abstract Predicted rates for solar neutrino experiments that are obtained with a modified stellar evolution code originally developed to study the advanced stages of stellar evolution are shown to be in agreement with other recently-calculated precise solar models to about 2% (0.2 SNU for the chlorine experiment). Different scenarios for pre-main sequence evolution are explored and are found to change the predicted rates for solar neutrino experiments by less than or of order 1%. The influence of the depth of the solar convective zone on the predicted solar neutrino fluxes is established by direct calculation. It is shown that a change in the calculated depth of the convective zone that is five times larger than the quoted helioseismological measurement uncertainty determined by Christensen-Dalsgaard, Gough, & Thompson causes a change in the predicted $^8$B neutrino flux of less than 7% and a change in the $^7$Be neutrino flux of less than 4%. Additionally, it is shown that the radiative opacities near the depth of the convective zone cannot differ from the standard OPAL values by more than about 12% without causing the calculated and measured depths of the convective zone to differ by more than five times the helioseismological measurement uncertainty. Publication: The Astrophysical Journal Pub Date: December 1994 DOI: 10.1086/175012 arXiv: arXiv:astro-ph/9406039 Bibcode: 1994ApJ...437..485B Keywords: Pre-Main Sequence Stars; Solar Convection (Astronomy); Solar Interior; Solar Neutrinos; Solar Oscillations; Stellar Evolution; Stellar Models; Computerized Simulation; Helioseismology; Mathematical Models; Solar Physics; CONVECTION; ELEMENTARY PARTICLES; STARS: EVOLUTION; STARS: PRE--MAIN-SEQUENCE; SUN: INTERIOR; SUN: OSCILLATIONS; Astrophysics E-Print: 28 pages. Postscript file including figures full text sources arXiv | ADS |

A review of stellar flares and their characteristics

We review the flaring activity of stars across the HR-diagram. Brightenings have been reported along the entire Main Sequence and in many stars off the Main Sequence. Some stars are decidedly young, others are in advanced stages of stellar evolution. Flares are common on stars with outer convection zones and outbursts have been reported also on other types of stars, although confirmations are needed for some of them. Analyses of flare occurrence sometimes find flares to be randomly distributed in time, and sometimes indicate a tendency for flares to come in groups. Preferred active longitudes have been suggested. Recent solar results, where the occurrence rate for flares is found to exhibit a periodicity of 152 days, suggest that stellar flare data should be reanalyzed over long time baselines to see if the present confusing situation can be resolved. The radiation from stellar flares is dominated by continuum emission and about equal amounts of energy have been recorded in the optical, UV, and X-ray regions of the spectrum. In solar flares strong continuum emission is rarely recorded and a large collection of bright emission lines takes prominence. Small flares occur more frequently than large ones and the latter have longer time-scales. Flare energies can exceed 1037 erg. The most productive flare stars are those where the convective envelopes occupy large volumes. Slow stellar rotation rates are believed to reduce the level when the star has been braked significantly from its young rotation rate.

A Review of Stellar Flares and Their Characteristics

AbstractWe review the flaring activity of stars across the HR-diagram. Brightenings have been reported along the entire Main Sequence and in many stars off the Main Sequence. Some stars are decidedly young, others are in advanced stages of stellar evolution. Flares are common on stars with outer convection zones and outbursts have been reported also on other types of stars, although confirmations are needed for some of them.Analyses of flare occurrence sometimes find flares to be randomly distributed in time, and sometimes indicate a tendency for flares to come in groups. Preferred active longitudes have been suggested. Recent solar results, where the occurrence rate for flares is found to exhibit a periodicity of 152 days, suggest that stellar flare data should be reanalyzed over long time baselines to see if the present confusing situation can be resolved.The radiation from stellar flares is dominated by continuum emission and about equal amounts of energy have been recorded in the optical, UV, and X-ray regions of the spectrum. In solar flares strong continuum emission is rarely recorded and a large collection of bright emission lines takes prominence. Small flares occur more frequently than large ones and the latter have longer time-scales. Flare energies can exceed 1037 erg. The most productive flare stars are those where the convective envelopes occupy large volumes. Slow stellar rotation rates are believed to reduce the level when the star has been braked significantly from its young rotation rate.

Images in the rocket ultraviolet - The initial helium abundance and distance modulus of the globular cluster M5 from photometry of horizontal-branch stars

A natural laboratory for the study of postmain-sequence evolution of low-mass (less than one solar mass) metal-poor stars is provided by globular clusters. These clusters are, therefore, a critical aid for developing an understanding of advanced stages of stellar evolution and of the chemical evolution of the Galaxy. Bohlin et al. (1983) have described a study of the postasymptotic branch star near the center of M5. The present investigation is concerned with the fainter horizontal-branch stars. The observations were made with the aid of a rocket-borne 38 cm f/9.0 Ritchey-Chretien telescope. Attention is given to payload and flight data, preflight bandpass calibration, the reduction of flight data, star selection, position measurement, photometry, the minimum observed horizontal-branch mass and inferences on mass loss, and individual UV-bright stars.

THE BARIUM STARS.

ABSTRACT The barium stars are Population I G-K giants that have enhanced abundances of carbon and s-process elements, and are probably related in their peculiarities to several other carbon enhanced red-giant types such as CH, R, N, and S stars. Since the abundance anomalies in the barium stars are likely the result of mixing of processed material from deep within a stellar interior, and since they are numerous with many bright examples suitable for detailed observations, these stars provide very valuable information on nucleosynthesis, and the advanced stages of stellar evolution. A clue to the origin of the anomalous abundances in the barium stars is the recent discovery that they are likely all members of binary systems.

The remarkable ultraviolet spectrum of the planetary nebula Abell 30

view Abstract Citations (39) References (18) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The remarkable ultraviolet spectrum of the planetary nebula Abell 30. Harrington, J. P. ; Feibelman, W. A. Abstract Abell 30 has been identified as a planetary nebula in which the nucleus has experienced a final helium shell flash after ejection of the original, outer envelope. Around the central star of the nebula, four knots of material are observed. In view of the importance of the chemical composition of the ejected material for studies of advanced stages of stellar evolution, clarification of the physical conditions in the knots is vital. Data obtained of Abell 30 with the aid of the International Ultraviolet Explorer (IUE) satellite are discussed along with aspects of extinction, the He II flux, ionic abundances, the C II lambda 4267 line, questions regarding the existence of a carbon-rich core in the knot, the heating of the nebular gas, the central star, and heating by suprathermal particles from the stellar wind. The UV spectrum of the inner nebulosity of Abell 30 indicates that an extraordinary amount of energy is being deposited in the gas. Publication: The Astrophysical Journal Pub Date: February 1984 DOI: 10.1086/161743 Bibcode: 1984ApJ...277..716H Keywords: Astronomical Spectroscopy; Planetary Nebulae; Stellar Evolution; Stellar Mass Ejection; Ultraviolet Spectra; Abundance; Chemical Composition; Coulomb Collisions; Electron Scattering; Gas Heating; Iue; Line Spectra; Radiant Flux Density; Stellar Winds; Astrophysics full text sources ADS | data products SIMBAD (1) MAST (1) INES (1)

The thermonuclear model for X-ray transients

view Abstract Citations (116) References (50) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The thermonuclear model for X-ray transients Wallace, R. K. ; Woosley, S. E. ; Weaver, T. A. Abstract One-dimensional numerical models for the accretion of nuclear material on the surface of neutron stars and subsequent thermonuclear ignition resulting in detectable hard gamma ray bursts are examined. The models were developed using the KEPLER computer code for advanced stages of stellar evolution. Nuclear energy generation on the surface of the star was taken to comprise a 19-isotope nuclear reaction network with full coupling for nuclei spanning the range H to Ni-56. Models for time-dependent convection and an equation of state incorporating leptonic contributions of relativity and degeneracy were employed for a reference 1.41 solar mass neutron star with a radius of 14.3 km. The star was assumed to accrete from 1/10 to the 10th or 11th solar masses per year, a rate which is shown to possibly stabilize. He ignition can occur once 10 to the 23rd to 25th g accumulates, resulting in super-Eddington luminosities and a radiatively driven wind observed as a gamma-ray burst. Publication: The Astrophysical Journal Pub Date: July 1982 DOI: 10.1086/160119 Bibcode: 1982ApJ...258..696W Keywords: Binary Stars; Neutron Stars; Red Giant Stars; Stellar Mass Accretion; Stellar Models; Thermonuclear Reactions; X Ray Sources; Eddington Approximation; Stellar Envelopes; Stellar Evolution; Stellar Luminosity; Stellar Mass Ejection; Stellar Temperature; Astrophysics full text sources ADS | Related Materials (1) Erratum: 1983ApJ...264..746W

Astrophysical implications of new light Higgs bosons

We explore the consequences of the existence of a new light pseudoscalar particle, such as the axion. Thermal energy can be converted into axions through annihilation (${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}\ensuremath{\gamma}h$), photoproduction ($\ensuremath{\gamma}e\ensuremath{\rightarrow}\mathrm{he}$), and plasma decay (${\ensuremath{\gamma}}_{p}\ensuremath{\rightarrow}\ensuremath{\gamma}h$). Explicit expressions for the cross sections and decay lifetimes are given. We conclude that axion production can occur in advanced stages of stellar evolution and in the big-bang creation of the universe. The most dramatic effect, however, is expected during gravitational collapse of massive stars where axions may help trigger a supernova explosion.

The infrared spectra of CRL 618 and HD 44179 /CRL 915/

view Abstract Citations (107) References (17) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The infrared spectra of CRL 618 and HD 44179 (CRL 915). Russell, R. W. ; Soifer, B. T. ; Willner, S. P. Abstract Spectrophotometry from 4 to 8 m is reported for the infrared sources CRL 618 and HD 44179 (CRL 915). In addition, 2-4 m spectrophotometry of CRL 618 is reported. Except for marginal detection of emission lines at 2.1 and 2.45 m, the spectrum of CRL 618 is featureless, consistent with graphite being the major constituent of the circumstellar dust cloud. Strong emission bands at 6.2 m and 7.7 m are found in the spectrum of HD 44179. These bands have been observed previously in NGC 7027 and M82. No positive identification of these bands is made. While both objects probably represent advanced stages of stellar evolution, the substantial differences between CRL 618 and HD 44179 suggest that they are members of different evolutionary sequences. Subject headings: infrared: sources - infrared: spectra - stars: individual Publication: The Astrophysical Journal Pub Date: March 1978 DOI: 10.1086/155937 Bibcode: 1978ApJ...220..568R Keywords: Infrared Spectra; Interstellar Matter; Stellar Evolution; Stellar Spectra; Abundance; Cosmic Dust; Emission Spectra; Stellar Spectrophotometry; Astronomy; Infrared Sources:Infrared Spectra full text sources ADS | data products SIMBAD (3)

Lithium and the s-PROCESS in Red-Giant Stars

view Abstract Citations (581) References (19) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Lithium and the s-PROCESS in Red-Giant Stars Cameron, A. G. W. ; Fowler, W. A. Abstract Some consequences are discussed of the possibility that helium-burning shell flashes in advanced stages of stellar evolution occasionally induce complete convection of the outer envelope down to the helium-burning shell. If the hydrogen mixing is relatively small for the first t0 seconds the result may be the production of large amounts of heavy elements by the s-process. When complete mixing commences, the 3He in the envelope will he converted to 7Be, and the subsequent delayed electron capture to form 7Li may allow enough lithium to remain near the surface to account for the very large lithium abundances in some S and carbon red-giant stars. On this basis the 7Li/6Li ratio in these stars should be quite large (>100). Publication: The Astrophysical Journal Pub Date: February 1971 DOI: 10.1086/150821 Bibcode: 1971ApJ...164..111C full text sources ADS | data products SIMBAD (5)

Supernova Light Curves and Presupernova Models

view Abstract Citations (20) References (25) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Supernova Light Curves and Presupernova Models Arnett, W. David Abstract Recent numerical models due to Grasberg and Nadexhin and to Morrison and Sartori of the light curve of supernovae of Types II and I are examined for their implications regarding presupernova evolutio and the nature of the supernova process. In these models an extremely extended envelope (radius r 1015 cm instead of r tO' cm considered by Colgate and \Vhite) for the presupernova is required. Suc] a structure is suggested by theoretical investigations of advanced stages of stellar evolution. Som hitherto inexplicable properties of supernovae of Types I and II can be explained. It is predicted tha presupernovae will be infrared sources of high luminosity, and that several may currently exist in th Galaxy. Publication: The Astrophysical Journal Pub Date: January 1971 DOI: 10.1086/150742 Bibcode: 1971ApJ...163...11A full text sources ADS |