The masses of hot subdwarfs

Abstract

Masses are a fundamental parameter, but they are not well known for most hot subdwarfs. In general, the mass of a hot subdwarf is derived with asteroseismology or dynamical methods, for which it is often difficult to obtain the necessary data from observations. We intend to find an approach to deriving the masses of hot subdwarfs from observational data in the literature. We presented full evolutionary calculations for hot subdwarfs in a wide mass range (0.33 $M_{\odot }$ to 1.4 $M_{\odot }$) for a Population I metallicity of $Z$=0.02, and obtained a relation between $M_{\mathrm{p}}$ and $\log (\frac{T_{\mathrm{eff}}^4}{g})$, where $M_{\mathrm{p}}$, $T_{\mathrm{eff}}$, and $g$ are the most probable mass, effective temperature, and gravity. This relation is used to study the masses of some observed hot subdwarfs. We proposed a method of determining the masses of hot subdwarfs. Using this method, we studied the masses of hot subdwarfs from the ESO supernova Ia progenitor survey and Hamburg quasar survey. The study shows that most of subdwarf B stars have masses between 0.42 and 0.54 $M_{\odot }$, whilst most sdO stars are in the range 0.40 $\sim$ 0.55 $M_{\odot }$. Comparing our study to the theoretical mass distributions of Han et al. (2003), we found that sdO stars with mass less than $\sim$ 0.5 $M_{\odot }$ may evolve from sdB stars, whilst most high-mass($>$ 0.5 $M_{\odot }$) sdO stars result from mergers directly.

5 pages, 6 figures, accepted for publication in A&A Letters

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Cited by in corpus (13)

• Hot subdwarf stars in close-up view I. Rotational properties of subdwarf B stars in close binary systems and nature of their unseen companions
• The shortest period sdB plus white dwarf binary CD-30 11223 (GALEX J1411-3053)
• New binaries among UV-selected, hot subdwarf stars and population properties
• On the formation of single and binary helium-rich sdO stars
• Binaries discovered by the MUCHFUSS project SDSS J08205+0008 - An eclipsing subdwarf B binary with brown dwarf companion
• Alone but not lonely: Observational evidence that binary interaction is always required to form hot subdwarf stars
• A selection of hot subluminous stars in the GALEX survey I. Correlation with the Guide Star Catalog
• Phases of Mass Transfer from Hot Subdwarfs to White Dwarf Companions and Their Photometric Properties
• Habitable Zones and UV Habitable Zones around Host Stars
• Photometry and spectroscopy of the new sdBV CS 1246
• Shell helium-burning hot subdwarf B stars as candidates for blue large-amplitude pulsators
• The double degenerate system NLTT 11748
• Stellar Parameters and Orbital Period Estimates for Composite-Spectrum sdB+MS Binaries from LAMOST