NOAO >   Observing Info >   Approved Programs >   2009B-0365

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Proposal Information for 2009B-0365


PI: Richard Wade, Pennsylvania State University, wade@astro.psu.edu
Address: Astronomy Department, 525 Davey Lab, University Park, PA 16802, USA

Title: F dwarfs with hidden hot subdwarf companions

Abstract: Theories of binary star evolution predict that an F dwarf star will sometimes be paired with a hot subdwarf (an ``sdB'' star). This is an essential prediction from theories that successfully account for pairings of sdB stars with white dwarf or lower-mass stars, but the F+sdB systems have not been observed before. The existence of such objects needs to be demonstrated, and their space density in the disk of the Galaxy needs to be determined. The distribution of orbital periods of the F+sdB systems depends on the processes of mass transfer/loss and angular momentum loss from the binary. Observations of F+sdB pairs provide a new way to help test and improve binary population synthesis (BPS) models, which are used throughout astrophysics to understand a wide variety of exotic objects and to predict their numbers. Using 2MASS and GALEX archival data, it is possible to identify F stars candidates with UV excesses (F+UVX). The 2.1m telescope with GoldCam spectrograph will be used to classify these color-selected F+UVX candidates on the MK system, reject interloping Algol systems and other objects that mimic F-star colors, and develop a representative sample of F+UVX stars that will be observed synoptically at high spectral resolution to obtain spectroscopic orbits.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



NOAO >   Observing Info >   Approved Programs >   2009B-0365

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