NOAO > Observing Info > Approved Programs > 2010B-0372
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NOAO > Observing Info > Approved Programs > 2010B-0372 |
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PI: Richard A. Wade, Pennsylvania State University, wade@astro.psu.edu
Address: Astronomy Department, 525 Davey Lab, University Park, PA 16802, USA
Title: Early F dwarfs with hidden hot subdwarf companions: completing the `winter' sample
Abstract:
Theories of binary star evolution predict that an early 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 only a
few F+sdB systems have been studied previously. Their space density in
the disk of the Galaxy needs to be determined. The distribution of
orbital periods of the F+sdB systems, which depends on the processes of
mass transfer/loss and angular momentum loss from the binary, needs to
be established. 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 early F star 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. For a sample of stars that can be observed
synoptically throughout the year and be of use to other observers, the
entire range of RA needs to be included; this proposal for 2010B
complements similar proposals which were awarded time in 2009B and
2010A, to complete the necessary MK classifications and other validation
in the fall/winter sky.
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 > 2010B-0372 |
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