The Metallicity Dependence of the Mass Loss of Early-Type Massive Stars

AbstractWe report on a comprehensive study of the wind properties of 115 O- and early B-type stars in the Galaxy and the Large Magellanic Clouds. This work is part of the VLT/FLAMES Survey of Massive Stars. The data is used to construct the empirical dependence of the mass-loss in stellar winds on the metal content of their atmospheres. The metal content of early-type stars in the Magellanic Clouds is discussed. Assuming a power-law dependence of mass loss on metal content, Ṁ ∝ Zm, we find m = 0.83 ± 0.16 from an analysis of the wind momentum luminosity relation (Mokiem et al. 2007b). This result is in good agreement with the prediction m = 0.69 ± 0.10 by Vink et al. (2001). Though the scaling agrees, the absolute empirical value of mass loss is found to be a factor of two higher than predictions. This may be explained by a modest amount of clumping in the outflows of the objects studied.

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The properties of early-type stars in the Magellanic Clouds

Proceedings of the International Astronomical Union ◽

10.1017/s1743921308028664 ◽

2008 ◽

Vol 4 (S256) ◽

pp. 325-336

Author(s):

Christopher J. Evans

Keyword(s):

Physical Properties ◽

Mass Loss ◽

Temperature Scale ◽

Massive Stars ◽

Magellanic Clouds ◽

Early Type ◽

The Past ◽

The Galaxy ◽

Stellar Temperature ◽

Early Type Stars

AbstractThe past decade has witnessed impressive progress in our understanding of the physical properties of massive stars in the Magellanic Clouds, and how they compare to their cousins in the Galaxy. I summarise new results in this field, including evidence for reduced mass-loss rates and faster stellar rotational velocities in the Clouds, and their present-day compositions. I also discuss the stellar temperature scale, emphasizing its dependence on metallicity across the entire upper-part of the Hertzsprung-Russell diagram.

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The VLT-FLAMES survey of massive stars: mass loss and rotation of early-type stars in the SMC

Astronomy and Astrophysics ◽

10.1051/0004-6361:20064995 ◽

2006 ◽

Vol 456 (3) ◽

pp. 1131-1151 ◽

Cited By ~ 84

Author(s):

M. R. Mokiem ◽

A. de Koter ◽

C. J. Evans ◽

J. Puls ◽

S. J. Smartt ◽

...

Keyword(s):

Mass Loss ◽

Massive Stars ◽

Early Type ◽

Early Type Stars

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Mass loss and evolution of massive stars in the Magellanic Clouds

Symposium - International Astronomical Union ◽

10.1017/s0074180900201228 ◽

1991 ◽

Vol 148 ◽

pp. 480-482 ◽

Cited By ~ 8

Author(s):

Claus Leitherer ◽

Norbert Langer

Keyword(s):

Mass Loss ◽

Iterative Procedure ◽

Metal Content ◽

Loss Rate ◽

Massive Stars ◽

Mass Loss Rate ◽

Magellanic Clouds ◽

Evolutionary Models ◽

Low Metallicity ◽

Self Consistency

The structure and evolution of massive stars is significantly influenced by effects of chemical composition in a low-metallicity environment (as compared to the solar neighbourhood, SN), such as the Magellanic Clouds. A fundamental ingredient in evolutionary models is the stellar mass-loss rate M. Lower metal content decreases the mass-loss rates derived theoretically, which in turn affects the stellar evolution models. On the other hand, different evolutionary models predict different stellar parameters (especially L), which again influence M so that an iterative procedure is required to achieve self-consistency.

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Spectroscopy of complete populations of Wolf-Rayet binaries in the Magellanic Clouds

Proceedings of the International Astronomical Union ◽

10.1017/s1743921319001303 ◽

2018 ◽

Vol 14 (S346) ◽

pp. 307-315

Author(s):

Tomer Shenar ◽

R. Hainich ◽

W.-R. Hamann ◽

A. F. J. Moffat ◽

H. Todt ◽

...

Keyword(s):

Spectral Analysis ◽

Mass Loss ◽

Massive Stars ◽

Large Population ◽

Magellanic Clouds ◽

Binary Interaction ◽

Stellar Winds ◽

Single Star ◽

Mass Removal ◽

Star Evolution

AbstractClassical Wolf-Rayet stars are evolved, hydrogen depleted massive stars that exhibit strong mass-loss. In theory, these stars can form either by intrinsic mass loss (stellar winds or eruptions), or via mass-removal in binaries. The Wolf-Rayet stars in the Magellanic Clouds are often thought to have originated through binary interaction due to the low ambient metallicity and, correspondingly, reduced wind mass-loss. We performed a complete spectral analysis of all known WR binaries of the nitrogen sequence in the Small and Large Magellanic Clouds, as well as additional orbital analyses, and constrained the evolutionary histories of these stars. We find that the bulk of Wolf-Rayet stars are luminous enough to be explained by single-star evolution. In contrast to prediction, we do not find clear evidence for a large population of low-luminosity Wolf-Rayet stars that could only form via binary interaction, suggesting a discrepancy between predictions and observations.

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X-ray diagnostics of massive star winds

Proceedings of the International Astronomical Union ◽

10.1017/s1743921317002952 ◽

2016 ◽

Vol 12 (S329) ◽

pp. 151-155

Author(s):

L. M. Oskinova ◽

R. Ignace ◽

D. P. Huenemoerder

Keyword(s):

High Resolution ◽

Stellar Wind ◽

Massive Star ◽

Massive Stars ◽

Stellar Winds ◽

X Rays ◽

Early Type ◽

Stellar Rotation ◽

X Ray ◽

Early Type Stars

AbstractObservations with powerful X-ray telescopes, such as XMM-Newton and Chandra, significantly advance our understanding of massive stars. Nearly all early-type stars are X-ray sources. Studies of their X-ray emission provide important diagnostics of stellar winds. High-resolution X-ray spectra of O-type stars are well explained when stellar wind clumping is taking into account, providing further support to a modern picture of stellar winds as non-stationary, inhomogeneous outflows. X-ray variability is detected from such winds, on time scales likely associated with stellar rotation. High-resolution X-ray spectroscopy indicates that the winds of late O-type stars are predominantly in a hot phase. Consequently, X-rays provide the best observational window to study these winds. X-ray spectroscopy of evolved, Wolf-Rayet type, stars allows to probe their powerful metal enhanced winds, while the mechanisms responsible for the X-ray emission of these stars are not yet understood.

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Evolution of rotation in rapidly rotating early-type stars during the main sequence with 2D models

Astronomy and Astrophysics ◽

10.1051/0004-6361/201832581 ◽

2019 ◽

Vol 625 ◽

pp. A89 ◽

Cited By ~ 5

Author(s):

D. Gagnier ◽

M. Rieutord ◽

C. Charbonnel ◽

B. Putigny ◽

F. Espinosa Lara

Keyword(s):

Angular Momentum ◽

Mass Loss ◽

Main Sequence ◽

Massive Stars ◽

Early Type ◽

Wind Regime ◽

Momentum Loss ◽

Angular Momentum Loss ◽

Rotational Evolution ◽

Early Type Stars

The understanding of the rotational evolution of early-type stars is deeply related to that of anisotropic mass and angular momentum loss. In this paper, we aim to clarify the rotational evolution of rapidly rotating early-type stars along the main sequence (MS). We have used the 2D ESTER code to compute and evolve isolated rapidly rotating early-type stellar models along the MS, with and without anisotropic mass loss. We show that stars with Z = 0.02 and masses between 5 and 7 M⊙ reach criticality during the main sequence provided their initial angular velocity is larger than 50% of the Keplerian one. More massive stars are subject to radiation-driven winds and to an associated loss of mass and angular momentum. We find that this angular momentum extraction from the outer layers can prevent massive stars from reaching critical rotation and greatly reduce the degree of criticality at the end of the MS. Our model includes the so-called bi-stability jump of the Ṁ − Teff relation of 1D-models. This discontinuity now shows up in the latitude variations of the mass-flux surface density, endowing rotating massive stars with either a single-wind regime (no discontinuity) or a two-wind regime (a discontinuity). In the two-wind regime, mass loss and angular momentum loss are strongly increased at low latitudes inducing a faster slow-down of the rotation. However, predicting the rotational fate of a massive star is difficult, mainly because of the non-linearity of the phenomena involved and their strong dependence on uncertain prescriptions. Moreover, the very existence of the bi-stability jump in mass-loss rate remains to be substantiated by observations.

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The Brightest Stars in the Magellanic Clouds and Other Late-Type Galaxies

Symposium - International Astronomical Union ◽

10.1017/s0074180900040134 ◽

1984 ◽

Vol 108 ◽

pp. 145-156

Author(s):

Roberta M. Humphreys

Keyword(s):

Mass Loss ◽

Stellar Evolution ◽

Stellar Population ◽

Massive Stars ◽

Magellanic Clouds ◽

Stellar Winds ◽

Stellar Content ◽

Late Type ◽

Observational Astronomy ◽

Distant Galaxies

The brightest stars always receive considerable attention in observational astronomy, but why are we so interested in these most luminous, and therefore most massive stars? These stars are our first probes for exploring the stellar content of distant galaxies. Admittedly, they are only the tip of the iceberg for the whole stellar population and very interesting processes are occurring among the less massive, older stars, but the most massive stars are our first indicators for studies of stellar evolution in other galaxies. They provide the first hint that stellar evolution may have been different in a particular galaxy because they evolve so quickly. The most luminous stars also highly influence their environments via their strong stellar winds and mass loss and eventually as supernovae.

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Mass-loss predictions and stellar masses of early-type stars

Symposium - International Astronomical Union ◽

10.1017/s0074180900211832 ◽

2003 ◽

Vol 212 ◽

pp. 164-165 ◽

Cited By ~ 1

Author(s):

Alex de Koter ◽

Jorick S. Vink

Keyword(s):

Mass Loss ◽

Massive Stars ◽

Spectroscopic Binaries ◽

Evolution Theory ◽

Early Type ◽

Direct Measurements ◽

Wind Theory ◽

Early Type Stars ◽

Stellar Masses

We show that the stellar masses implied by our predictions of the wind properties of massive stars are in agreement with masses derived from evolution theory and from direct measurements using spectroscopic binaries, contrary to previous attempts to derive masses from wind theory.

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