NOAO > Observing Info > Approved Programs > 2013A-0288
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NOAO > Observing Info > Approved Programs > 2013A-0288 |
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PI: Brad N. Barlow, Pennsylvania State University, bbarlow@psu.edu
Address: Astronomy Department, 525 Davey Lab, University Park, PA 16802, USA
CoI: Richard A. Wade, Pennsylvania State University
CoI: Jackson Norris, Pennsylvania State University
Title: Radial Velocities of Hot Subdwarfs in Resolved Pairs
Abstract:
Binary population synthesis (BPS) models show that common--envelope
and Roche lobe overflow processes can strip a red giant of its envelope
and form a hot subdwarf B (sdB) star with a binary companion, but the
details of these processes are unclear. Because of these strong
interactions, the sdB's companion cannot be used to definitively
determine such important sdB parameters as the age, luminosity,
metallicity, and distance. We have found a significant number of sdB
stars with resolved, visual companions separated by 4-20 arcseconds, too
far for the cool companion to have played a significant role in the
formation of the sdB. Their published magnitudes and proper motions are
consistent with their being true binaries, but radial velocity (RV)
measurements are needed to confirm this. We propose spectroscopic
observations with the Kitt Peak 4--m telescope to measure the component
RVs in each pair and remove chance alignments from our study. For pairs
that turn out to be true binaries, we will use the spectra of the cool
companion to infer distance and initial metallicity of the sdB. The
masses and ages of the companions will constrain the empirical mass
distribution of sdB progenitors, which will help improve BPS codes.
National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360
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NOAO > Observing Info > Approved Programs > 2013A-0288 |
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