scholarly journals Rotational mixing in close binaries

2008 ◽  
Vol 4 (S252) ◽  
pp. 365-370 ◽  
Author(s):  
S. E. de Mink ◽  
M. Cantiello ◽  
N. Langer ◽  
S.-Ch. Yoon ◽  
I. Brott ◽  
...  
Keyword(s):  
Massive Stars ◽  
Roche Lobe ◽  
Close Binaries ◽  
Uncertain Process ◽  
Evolutionary Scenario ◽  
Stellar Models

AbstractRotational mixing a very important but uncertain process in the evolution of massive stars. We propose to use close binaries to test its efficiency. Based on rotating single stellar models we predict nitrogen surface enhancements for tidally locked binaries. Furthermore we demonstrate the possibility of a new evolutionary scenario for very massive (M > 40M⊙) close (P < 3 days) binaries: Case M, in which mixing is so efficient that the stars evolve quasi-chemically homogeneously, stay compact and avoid any Roche-lobe overflow, leading to very close (double) WR binaries.

scholarly journals On the evolutionary time scale of the accreting component in massive close binaries: consequences for the supernova event

1981 ◽  
Vol 59 ◽  
pp. 465-468
Author(s):  
C. Doom ◽  
J.P. De Grève
Keyword(s):  
Mass Loss ◽  
Mass Exchange ◽  
Stellar Wind ◽  
Time Scale ◽  
Roche Lobe ◽  
Close Binaries ◽  
Evolutionary Time ◽  
Hydrogen Burning ◽  
Evolutionary Time Scale ◽  
Evolutionary Scenario

AbstractThe remaining core hydrogen burning lifetime after a case B of mass exchange is computed for the mass gaining component in massive close binaries. Effects of stellar wind mass loss and mass loss during Roche Lobe OverFlow (RLOF) are included. Consequences for the evolutionary scenario are discussed.

scholarly journals Developments in Physics of Massive Stars

2007 ◽  
Vol 3 (S250) ◽  
pp. 147-160 ◽  
Author(s):  
Georges Meynet ◽  
Sylvia Ekström ◽  
André Maeder ◽  
Raphael Hirschi ◽  
Cyril Georgy ◽  
...  
Keyword(s):  
Massive Star ◽  
Massive Stars ◽  
Stellar Models

AbstractNew constraints on stellar models are provided by large surveys of massive stars, interferometric observations and asteroseismology. After a review of the main results so far obtained, we present new results from rotating models and discuss comparisons with observed features. We conclude that rotation is a key feature of massive star physics.

Complete Stellar Models for Massive Stars

1995 ◽  
pp. 300-304
Author(s):  
D. Schaerer ◽  
A. De Koter ◽  
W. Schmutz
Keyword(s):  
Massive Stars ◽  
Stellar Models

scholarly journals Stellar models and isochrones from low-mass to massive stars including pre-main sequence phase with accretion

2019 ◽  
Vol 624 ◽  
pp. A137 ◽  
Author(s):  
L. Haemmerlé ◽  
P. Eggenberger ◽  
S. Ekström ◽  
C. Georgy ◽  
G. Meynet ◽  
...  
Keyword(s):  
Star Formation ◽  
Stellar Evolution ◽  
Main Sequence ◽  
Massive Stars ◽  
Mass Range ◽  
Stellar Clusters ◽  
Solar Metallicity ◽  
Low Mass ◽  
Stellar Models ◽  
Young Clusters

Grids of stellar models are useful tools to derive the properties of stellar clusters, in particular young clusters hosting massive stars, and to provide information on the star formation process in various mass ranges. Because of their short evolutionary timescale, massive stars end their life while their low-mass siblings are still on the pre-main sequence (pre-MS) phase. Thus the study of young clusters requires consistent consideration of all the phases of stellar evolution. But despite the large number of grids that are available in the literature, a grid accounting for the evolution from the pre-MS accretion phase to the post-MS phase in the whole stellar mass range is still lacking. We build a grid of stellar models at solar metallicity with masses from 0.8 M⊙ to 120 M⊙, including pre-MS phase with accretion. We use the GENEC code to run stellar models on this mass range. The accretion law is chosen to match the observations of pre-MS objects on the Hertzsprung-Russell diagram. We describe the evolutionary tracks and isochrones of our models. The grid is connected to previous MS and post-MS grids computed with the same numerical method and physical assumptions, which provides the widest grid in mass and age to date.

scholarly journals Non-standard s-process in massive rotating stars

2018 ◽  
Vol 618 ◽  
pp. A133 ◽  
Author(s):  
Arthur Choplin ◽  
Raphael Hirschi ◽  
Georges Meynet ◽  
Sylvia Ekström ◽  
Cristina Chiappini ◽  
...  
Keyword(s):  
Critical Velocity ◽  
Rotation Rate ◽  
Reaction Rate ◽  
Massive Stars ◽  
Strong Impact ◽  
Light Elements ◽  
Rotating Stars ◽  
Stellar Models ◽  
Fast Rotating

Context. Recent studies show that rotation significantly affects the s-process in massive stars. Aims. We provide tables of yields for non-rotating and rotating massive stars between 10 and 150 M⊙ at Z = 10−3 ([Fe/H] = −1.8). Tables for different mass cuts are provided. The complete s-process is followed during the whole evolution with a network of 737 isotopes, from hydrogen to polonium. Methods. A grid of stellar models with initial masses of 10, 15, 20, 25, 40, 60, 85, 120, and 150 M⊙ and with an initial rotation rate of both 0% or 40% of the critical velocity was computed. Three extra models were computed in order to investigate the effect of faster rotation (70% of the critical velocity) and of a lower 17O(α, γ) reaction rate. Results. At the considered metallicity, rotation has a strong impact on the production of s-elements for initial masses between 20 and 60 M⊙. In this range, the first s-process peak is boosted by 2−3 dex if rotation is included. Above 60 M⊙, s-element yields of rotating and non-rotating models are similar. Increasing the initial rotation from 40% to 70% of the critical velocity enhances the production of 40 ≲ Z ≲ 60 elements by ∼0.5−1 dex. Adopting a reasonably lower 17O(α, γ) rate in the fast-rotating model (70% of the critical velocity) boosts again the yields of s-elements with 55 ≲ Z ≲ 82 by about 1 dex. In particular, a modest amount of Pb is produced. Together with s-elements, some light elements (particularly fluorine) are strongly overproduced in rotating models.

scholarly journals Empirical Determination of the Gravity-Darkening Exponent for the Secondary Components Filling the Roche Lobe in Semi-Detached Close Binary Systems

1988 ◽  
Vol 108 ◽  
pp. 217-218
Author(s):  
Masatoshi Kitamura ◽  
Yasuhisa Nakamura
Keyword(s):  
Binary Systems ◽  
Main Sequence ◽  
Close Binary System ◽  
Roche Lobe ◽  
Close Binary ◽  
Close Binaries ◽  
Main Sequence Stars ◽  
Local Gravity ◽  
Subsurface Layers

The ordinary semi-detached close binary system consists of a main-sequence primary and subgiant (or giant) secondary component where the latter fills the Roche lobe. From a quantitative analysis of the observed ellipticity effect, Kitamura and Nakamura (1986) have deduced empirical values of the exponent of gravity-darkening for distorted main-sequence stars in detached systems and found that the empirical values of the exponent for these stars with early-type spectra are close to the unity, indicating that the subsurface layers of early-main sequence stars in close binaries are actually in radiative equilibrium. The exponent of gravity-darkening can be defined by H ∝ gα with H as the bolonetric surface brightness and g as the local gravity on the stellar surface.

scholarly journals Convective zones in the envelope of massive stars

1994 ◽  
Vol 162 ◽  
pp. 67-68
Author(s):  
Frank M. Alberts
Keyword(s):  
Main Sequence ◽  
Massive Stars ◽  
Convective Zone ◽  
Helium Burning ◽  
The Core ◽  
Negligible Amount ◽  
Stellar Models

In the calculation of stellar models with the Cox–Stewart opacities no convective zones in the outer layers of massive stars appear. The new OPAL opacities (Rogers & Iglesias, 1992) show a significant bump in the opacity near temperatures of log T = 5.2. This opacity effect results in a small convective zone in the envelope of stars with mass ranging from 15 M⊙ to 150 M⊙, apart from possible convective zones caused by ionization. This was also briefly mentioned by Glatzel & Kiriakidis (1993). For stars on the main sequence this zone is small, about 1% of its radius on the zero age main sequence up to 7% at the onset of the core helium burning and contains a negligible amount of mass. For helium burning stars, however, this convective zone moves inward, keeping the same size but containing more and more mass.

scholarly journals The influence of stellar wind mass loss on the evolution of massive close binaries.

1979 ◽  
Vol 83 ◽  
pp. 409-414
Author(s):  
D. Vanbeveren ◽  
J.P. De Grève ◽  
C. de Loore ◽  
E.L. van Dessel
Keyword(s):  
Mass Loss ◽  
Stellar Wind ◽  
Binary Systems ◽  
Mass Loss Rate ◽  
Radiation Force ◽  
Roche Lobe ◽  
Close Binaries ◽  
Massive Binary Systems ◽  
Binary Evolution ◽  
X Ray Binaries

It is generally accepted that massive (and thus luminous) stars lose mass by stellar wind, driven by radiation force (Lucy and Solomon, 1970; Castor et al. 1975). For the components of massive binary systems, rotational and gravitational effects may act together with the radiation force so as to increase the mass loss rate. Our intention here is to discuss the influence of a stellar wind mass loss on the evolution of massive close binaries. During the Roche lobe overflow phase, mass and angular momentum can leave the system. Possible reasons for mass loss from the system are for example the expansion of the companion due to accretion of the material lost by the mass losing star (Kippenhahn and Meyer-Hofmeister, 1977) or the fact that due to the influence of the radiation force in luminous stars, mass will be lost over the whole surface of the star and not any longer through a possible Lagrangian point as in the case of classical Roche lobe overflow (Vanbeveren, 1978). We have therefore investigated the influence of both processes on binary evolution. Our results are applied to 5 massive X-ray binaries with a possible implication for the existence of massive Wolf Rayet stars with a very close invisible compact companion. A more extended version of this talk is published in Astronomy and Astrophysics (Vanbeveren et al. 1978; Vanbeveren and De Grève, 1978). Their results will be briefly reviewed.

scholarly journals The stability of massive stars

1994 ◽  
Vol 162 ◽  
pp. 73-74
Author(s):  
W. Glatzel ◽  
M. Kiriakidis ◽  
K.J. Fricke
Keyword(s):  
Massive Stars ◽  
Mass Limit ◽  
Physical Explanation ◽  
Stellar Objects ◽  
Fundamental Interest ◽  
Stability Properties ◽  
Luminous Blue Variables ◽  
Stellar Models ◽  
The Stability

An investigation of the stability properties of stellar models describing massive stars is motivated observationally by the necessity to explain the observed Humphreys - Davidson (HD) limit and the variability of the most massive stars known, i.e. the existence of luminous blue variables (LBVs). Theoretically, a determination of the upper mass limit for stable stellar objects together with its physical explanation and interpretation is of fundamental interest.

scholarly journals Massive stars: stellar models and stellar yields, impact on Galactic Archaeology

2017 ◽  
Vol 13 (S334) ◽  
pp. 170-177
Author(s):  
Georges Meynet ◽  
Arthur Choplin ◽  
Sylvia Ekström ◽  
Cyril Georgy
Keyword(s):  
Magnetic Fields ◽  
Mass Loss ◽  
Massive Stars ◽  
Stellar Winds ◽  
Stellar Models ◽  
The Impact

AbstractThe physics of massive stars depends (at least) on convection, mass loss by stellar winds, rotation, magnetic fields and multiplicity. We briefly discuss the impact of the first three processes on the stellar yields trying to identify some guidelines for future works.

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