AAS 204th Meeting, June 2004
Session 6 Stars: Winkin' and Blinkin'
Poster, Monday, May 31, 2004, 9:20am-6:30pm, Ballroom

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[6.08] SdB stars: low-resolution survey has far-reaching applications

E. Hyde, E. M. Green, B. For, K. Bonga (The University of Arizona)

Preliminary results from a low resolution (8Å), high S/N (~100) spectroscopic survey of subdwarf B (sdB) stars brighter than V ~ 14 show potential contributions of sdB stars to aspects of both binary mass transfer and astroseismology. About 400 known or suspected sdB stars were selected from the Palomar-Green catalog (1986), Wesemael et al. (1992), and the electronic version of the revised "Kilkenny" catalog of hot subdwarfs (Wade et al., in preparation), among others. The primary goal of this survey is to distinguish a large sample of true Extended Horizontal Branch (EHB) stars. Photometric and low S/N spectroscopic samples such as these often include subdwarf O stars (possible post-asymptotic giant branch stars), blue horizontal branch stars, main sequence B and A stars, low metallicity F stars, white dwarfs and others, in addition to sdB stars on the EHB. Our sdB spectra, which cover all the Balmer lines from H\alpha to the Balmer jump, will eventually be fit to atmospheric models to derive effective temperatures and gravities. They will be used to select follow-up targets for studies of mass transfer/common envelope binaries, and irregular multimode pulsators, common among EHB stars. If large enough samples are selected these binary mass transfer and astroseismology topics become extremely important. However, our high S/N spectra by themselves are sufficient to distinguish sdB stars from most other contaminants, except for cases of composite spectra. For an additional classification criterion, we have cross-correlated our sample with the 2MASS catalog. Following Stark & Wade (2003), we reaffirm the value of combining V + JHK colors for detection of binaries with low-mass main sequence companions.

The author(s) of this abstract have provided an email address for comments about the abstract: ehyde@u.arizona.edu

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