g-mode trapping and period spacings in hot B subdwarf stars
نویسندگان
چکیده
منابع مشابه
Hot subdwarf stars in close-up view*
The origin of hot subdwarf B stars (sdBs) is still unclear. About half of the known sdBs are in close binary systems for which common envelope ejection is the most likely formation channel. Little is known about this dynamic phase of binary evolution. Since most of the known sdB systems are single-lined spectroscopic binaries, it is difficult to derive masses and unravel the companions’ nature,...
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We discuss whether the hypothesis that “all (or most) subdwarfs are in close binaries” is supported by the frequently reported observations of photometrically or spectroscopically composite character of many hot subdwarf stars. By way of a possible counter-argument, we focus on resolved companions (optical pairs) of hot subdwarf stars. On a statistical basis, many of these are physically associ...
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We present the results of Monte Carlo mass-loss computations for hot low-mass stars, specifically for Subdwarf B (SdB) stars. It is shown that the massloss rates on the Horizontal Branch (HB) computed from radiative line-driven wind models are not high enough to create SdB stars. We argue, however, that mass loss plays a role in the chemical abundance patterns observed both in field SdB stars, ...
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We evaluate the influence of NLTE effects on hydrogen and helium lines of high gravity stars. This investigation covers the classes of hydrogen-rich DA and DAO white dwarfs and helium-rich DO white dwarfs. Furthermore, model atmospheres of hydrogen-rich subdwarf B (sdB) stars are investigated. Implications for model atmosphere analyses of such stars are discussed. Pure hydrogen atmospheres of D...
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The identification of non-radial g-mode oscillations as the cause of variability in cool subdwarf B stars (PG1716 variables) has been frustrated by a 5 000K discrepancy between the observed and theoretical blue edge of the instability domain (Fontaine et al. 2003). A major component in the solution to this problem has been identified by (a) using updated OP instead of OPAL opacities and (b) con...
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ژورنال
عنوان ژورنال: Proceedings of the International Astronomical Union
سال: 2013
ISSN: 1743-9213,1743-9221
DOI: 10.1017/s1743921313014737