Spectroscopic analysis of sdB stars from the ESO Supernova Ia Progenitor Survey

Abstract

We report on the analysis of high-resolution optical spectra for 77 subdwarf B (sdB) stars from the ESO Supernova Ia Progenitor Survey. Effective temperature, surface gravity, and photospheric helium abundance are determined simultaneously by spectral line profile fitting of hydrogen and helium lines, and are found to be in agreement with previous studies of sdB stars. 24 objects show spectral signs of a cool companion, being either companion absorption lines or a flux contribution at Halpha. Five stars with relatively high luminosity show peculiar Halpha profiles, possibly indicating stellar winds. Our results are compared to recent theoretical simulations by Han et al. (2003) for the distribution in effective temperature and surface gravity, and are found to agree very well with these calculations. Finally we present a binary system consisting of two helium-rich hot subdwarfs.

arXiv comment8 pages, 6 figures. To appear in "Extreme Horizontal Branch Stars and Related Objects", Astrophysics and Space Science, Kluwer Academic Publishers, edited by P. F. L. Maxted

References in corpus (7)

• The origin of sdB stars (II)
• Ultraviolet Radiation from Evolved Stellar Populations -- I. Models
• The binary fraction of extreme horizontal branch stars
• Orbital periods of twenty two subdwarf B stars
• A Comparative Study of the Mass Distribution of Extreme Ultraviolet-Selected White Dwarfs
• Spectral analysis of sdB stars from the Hamburg Quasar Survey
• Search for progenitors of supnernovae type Ia with SPY

Cited by in corpus (9)

• A binary model for the UV-upturn of elliptical galaxies (MNRAS version)
• Close binary EHB stars from SPY
• Hot subdwarfs from the ESO Supernova Ia Progenitor Survey: II. Atmospheric parameters of subdwarf O stars
• New binaries among UV-selected, hot subdwarf stars and population properties
• On the formation of single and binary helium-rich sdO stars
• Discovery of extremely lead-rich subdwarfs: does heavy metal signal the formation of subdwarf B stars?
• Abundance analyses of helium-rich subluminous B stars
• A seismic approach to testing different formation channels of subdwarf B stars
• Spectroscopic Orbital Elements for the Helium-Rich Subdwarf Binary PG1544+488