NOAO > Observing Info > Approved Programs > 2009B-0179
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NOAO > Observing Info > Approved Programs > 2009B-0179 |
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PI: Andrzej Baran, Cracow Pedagogical University, sfbaran@cyf-kr.edu.pl
Address: Mathematics, Physics and Material Science, Podchorazych 2, Krakow 30-084, Poland
CoI: Mike Reed, Missouri State University
CoI: Justin Gilker, Missouri State University
Title: RATJ0455+1305 - a prominent candidate for probing the interiors of subdwarf B stars
Abstract:
Hot subdwarfs pulsators (sdBV) of hybrid nature (p- and g-modes in
one star) constitute a small but important sample of sdBV stars
discovered so far. Their p-modes sample their outer layers, while the g-
modes probe deeper into the star. Additionally, there are many more
model g-mode periods then observed ones, so the p-modes are critical for
primary model constraints. As such, the hybrid pulsators are currently
unique for understanding sdB stars from surface to core. For this
project we will obtain photometry of a newly detected hybrid sdBV star:
RAT0455+1305. The Fourier spectrum of some preliminary data shows that
at least one high-amplitude pressure (p-)mode and one gravity (g-)mode
is present in the star. However, the amplitude of the g-mode is near
the detection threshold and its presence should be confirmed with better
quality data. These proposed data will seek to confirm the g-mode
period and detect more frequencies (of both p- and g-mode) to allow a
full asteroseismic analysis. A fully resolved frequency spectrum allows
us to build up a theoretical model, which is equivalent to the
derivation of stellar mass, radius, mass of the hydrogen envelope and
time since the Zero-Age-Extended-Horizontal-Branch. These parameters
are necessary to understand the evolution of hot subdwarf stars, which
themselves are important for diffusive processes, stellar population
synthesis, and a complete picture of stellar evolution.
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 > 2009B-0179 |
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