Populations of massive stars in galaxies, implications for the stellar evolution theory

The study of the stars that explode as supernovae used to be a forensic study, working backwards from the remnants of the star. This changed in 1987 when the first progenitor star was identified in pre-explosion images. Currently, there are eight detected progenitors with another 21 non-detections, for which only a limit on the pre-explosion luminosity can be placed. This new avenue of supernova research has led to many interesting conclusions, most importantly that the progenitors of the most common supernovae, type IIP, are red supergiants, as theory has long predicted. However, no progenitors have been detected thus far for the hydrogen-free type Ib/c supernovae, which, given the expected progenitors, is an unlikely result. Also, observations have begun to show evidence that luminous blue variables, which are among the most massive stars, may directly explode as supernovae. These results contradict the current stellar evolution theory. This suggests that we may need to update our understanding.

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New prescriptions of turbulent transport from local numerical simulations

Proceedings of the International Astronomical Union ◽

10.1017/s1743921314006292 ◽

2014 ◽

Vol 9 (S307) ◽

pp. 70-75

Author(s):

V. Prat ◽

F. Lignières ◽

G. Lesur

Keyword(s):

Numerical Simulations ◽

Stellar Evolution ◽

Turbulent Mixing ◽

Massive Stars ◽

Turbulent Transport ◽

Strong Impact ◽

Evolution Theory ◽

Transport Models ◽

Chemical Stratification ◽

The Impact

AbstractMassive stars often experience fast rotation, which is known to induce turbulent mixing with a strong impact on the evolution of these stars. Local direct numerical simulations of turbulent transport in stellar radiative zones are a promising way to constrain phenomenological transport models currently used in many stellar evolution codes. We present here the results of such simulations of stably-stratified sheared turbulence taking notably into account the effects of thermal diffusion and chemical stratification. We also discuss the impact of theses results on stellar evolution theory.

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The effect of rotation on RGB surface abundances

Symposium - International Astronomical Union ◽

10.1017/s0074180900116870 ◽

1997 ◽

Vol 189 ◽

pp. 349-354

Author(s):

C. Charbonnel

Keyword(s):

Stellar Evolution ◽

Globular Cluster ◽

Massive Stars ◽

Observational Evidence ◽

Evolution Theory ◽

Mixing Processes ◽

Giant Stars ◽

The Subject ◽

Abundance Anomalies ◽

Chemical Anomalies

Pop II field and globular cluster giant stars (and, to a less extent, Pop I giants) exhibit chemical anomalies which are not predicted by standard stellar evolution theory. Two hypotheses have been proposed to explain these abundance variations, namely the primordial and the evolutionary explanations. A primordial origin for intracluster abundance anomalies (see e.g. Cottrel & Da Costa 1981) would be related to inhomogeneities in the cluster material due to pollution by a prior generation of massive stars. In the evolutionary hypothesis, abundance variations would be due to nuclear and mixing processes internal to the giant stars themselves. Many good reviews exist on the subject (see e.g. Briley et al. 1994a, Kraft 1994), in which observational evidence supporting both hypotheses are presented. In this conference, Da Costa recalls the most recent observational data, and some excellent poster contributions bring essential clues to the subject.

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Common envelope evolution of massive stars

Proceedings of the International Astronomical Union ◽

10.1017/s1743921318007433 ◽

2018 ◽

Vol 14 (S346) ◽

pp. 449-454 ◽

Cited By ~ 1

Author(s):

Paul M. Ricker ◽

Frank X. Timmes ◽

Ronald E. Taam ◽

Ronald F. Webbink

Keyword(s):

Black Hole ◽

Stellar Evolution ◽

Massive Stars ◽

Evolution Theory ◽

Helium Burning ◽

Massive Black Hole ◽

Common Envelope ◽

Binary Black Hole ◽

Low Metallicity ◽

The Common

AbstractThe discovery via gravitational waves of binary black hole systems with total masses greater than 60Mʘ has raised interesting questions for stellar evolution theory. Among the most promising formation channels for these systems is one involving a common envelope binary containing a low metallicity, core helium burning star with mass ⁓30 – 40Mʘ and a black hole with mass ⁓30 – 40Mʘ. For this channel to be viable, the common envelope binary must eject more than half the giant star’s mass and reduce its orbital separation by as much as a factor of 80. We discuss issues faced in numerically simulating the common envelope evolution of such systems and present a 3D AMR simulation of the dynamical inspiral of a low-metallicity red supergiant with a massive black hole companion.

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Synthetic HR Diagrams for Luminous Stars: A Test of Stellar Evolution Theory

Symposium - International Astronomical Union ◽

10.1017/s0074180900148806 ◽

1986 ◽

Vol 116 ◽

pp. 121-122

Author(s):

Emma Nasi

Keyword(s):

Stellar Evolution ◽

Star Formation Rate ◽

Massive Stars ◽

Formation Rate ◽

Theoretical Models ◽

Mass Function ◽

Initial Mass Function ◽

The Sun ◽

Evolution Theory ◽

Hr Diagram

The composite HR diagram for luminous stars in our galaxy by Humphreys and McElroy(1984) is the only source which provides enough data for the comparison with the results of massive stars theoretical models. The luminosity limit for completeness of Humphreys' and McElroy's catalog(l984) is about MBol=−8 mag, when restricted to 3 Kpc from the Sun. Inside these limits there are 378 luminous stars in galactic associations and clusters, whose distances are known with sufficient reliability. The correspondent observational HR diagram is reproduced in Fig. 1. Synthetic HR diagrams for massive stars were constructed with the aim of reproducing the observed features for galactic luminous stars. By means of a Montecarlo technique, stars were randomly distributed in the MBol−Log Teff plane, weighted on the Salpeter's initial mass function and with a constant star formation rate.

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Populations of OB-type stars in galaxies

Proceedings of the International Astronomical Union ◽

10.1017/s1743921311010477 ◽

2010 ◽

Vol 6 (S272) ◽

pp. 233-241

Author(s):

Christopher J. Evans

Keyword(s):

Stellar Evolution ◽

Massive Stars ◽

Spectral Synthesis ◽

High Redshift ◽

Young Star ◽

Magellanic Clouds ◽

Star Forming ◽

The Galaxy ◽

External Galaxies

AbstractOne of the challenges for stellar astrophysics is to reach the point at which we can undertake reliable spectral synthesis of unresolved populations in young, star-forming galaxies at high redshift. Here I summarise recent studies of massive stars in the Galaxy and Magellanic Clouds, which span a range of metallicities commensurate with those in high-redshift systems, thus providing an excellent laboratory in which to study the role of environment on stellar evolution. I also give an overview of observations of luminous supergiants in external galaxies out to a remarkable 6.7 Mpc, in which we can exploit our understanding of stellar evolution to study the chemistry and dynamics of the host systems.

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A hot and fast ultra-stripped supernova that likely formed a compact neutron star binary

Science ◽

10.1126/science.aas8693 ◽

2018 ◽

Vol 362 (6411) ◽

pp. 201-206 ◽

Cited By ~ 33

Author(s):

K. De ◽

M. M. Kasliwal ◽

E. O. Ofek ◽

T. J. Moriya ◽

J. Burke ◽

...

Keyword(s):

Neutron Star ◽

Kinetic Energy ◽

Light Curve ◽

Stellar Evolution ◽

Binary Systems ◽

Massive Stars ◽

Compact Binary ◽

Compact Binary Systems ◽

Supernova Explosions ◽

Star Binary

Compact neutron star binary systems are produced from binary massive stars through stellar evolution involving up to two supernova explosions. The final stages in the formation of these systems have not been directly observed. We report the discovery of iPTF 14gqr (SN 2014ft), a type Ic supernova with a fast-evolving light curve indicating an extremely low ejecta mass (≈0.2 solar masses) and low kinetic energy (≈2 × 1050ergs). Early photometry and spectroscopy reveal evidence of shock cooling of an extended helium-rich envelope, likely ejected in an intense pre-explosion mass-loss episode of the progenitor. Taken together, we interpret iPTF 14gqr as evidence for ultra-stripped supernovae that form neutron stars in compact binary systems.

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Bimodal regime in young massive clusters leading to subsequent stellar generations

Proceedings of the International Astronomical Union ◽

10.1017/s1743921315009023 ◽

2015 ◽

Vol 12 (S316) ◽

pp. 294-301

Author(s):

Richard Wünsch ◽

Jan Palouš ◽

Guillermo Tenorio-Tagle ◽

Casiana Muñoz-Tuñón ◽

Soňa Ehlerová

Keyword(s):

Stellar Evolution ◽

Column Density ◽

First Generation ◽

Massive Stars ◽

Ionising Radiation ◽

Cluster Center ◽

Stellar Winds ◽

Hot Gas ◽

Massive Clusters ◽

By Products

AbstractMassive stars in young massive clusters insert tremendous amounts of mass and energy into their surroundings in the form of stellar winds and supernova ejecta. Mutual shock-shock collisions lead to formation of hot gas, filling the volume of the cluster. The pressure of this gas then drives a powerful cluster wind. However, it has been shown that if the cluster is massive and dense enough, it can evolve in the so–called bimodal regime, in which the hot gas inside the cluster becomes thermally unstable and forms dense clumps which are trapped inside the cluster by its gravity. We will review works on the bimodal regime and discuss the implications for the formation of subsequent stellar generations. The mass accumulates inside the cluster and as soon as a high enough column density is reached, the interior of the clumps becomes self-shielded against the ionising radiation of stars and the clumps collapse and form new stars. The second stellar generation will be enriched by products of stellar evolution from the first generation, and will be concentrated near the cluster center.

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