SETI bioastro: Oscillating Blue Stragglers, gamma Doradus stars and eclipsing binaries in the o

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Astrophysics, abstract
astro-ph/0703111

From: Torben Arentoft [view email]

Date: Tue, 6 Mar 2007 11:27:49 GMT (698kb)

Oscillating Blue Stragglers, gamma Doradus stars and eclipsing binaries in
the open cluster NGC2506

Authors: T. Arentoft, J. De Ridder, F. Grundahl, L. Glowienka, C. Waelkens,
M.-A. Dupret, A. Grigahcene, K. Lefever, H. R. Jensen, M. Reyniers, S.
Frandsen, H. Kjeldsen

Comments: 17 pages, 20 figures, accepted for publication in A&A

This is the first step in a project to combine studies of eclipsing binaries
and oscillating stars to probe the interior of Blue Stragglers (BS). This
may imply a way to discriminate observationally between different birth
mechanisms of BS stars. We study the open cluster NGC2506 which contains
oscillating BS stars and detached eclipsing binaries for which accurate
parameters can be derived. This will tightly constrain the cluster isochrone
and provide an absolute mass, radius and luminosity-scale for the cluster
stars along with the cluster age, metallicity and distance. The present work
focuses on obtaining the light curves of the binaries and determine their
orbital periods, on obtaining power spectra of the oscillating BS stars to
select targets for follow-up studies, and on searching for gamma Doradus
type variables which are also expected to be present in the cluster. With a
two-colour, dual-site photometric campaign we obtained 3120 CCD-images of
NGC2506 spread over four months. We analysed the BI time-series of the
oscillating stars and used simulations to derive statistical uncertainties
of the resulting frequencies, amplitudes and phases. A preliminary
mode-identification was performed using frequency ratios for the oscillating
BS stars, and amplitude ratios and phase differences for a population of
newly detected gamma Doradus stars. We quadrupled the number of known
variables in NGC2506 by discovering 3 new oscillating BS stars, 15 gamma
Doradus stars and four new eclipsing binaries. The orbital periods of 2
known, detached eclipsing binaries were derived. We discovered a BS star
with both p-mode and g-mode variability and we confronted our gamma Doradus
observations with state-of-the-art seismic models, but found significant
discrepancy between theory and observations.

http://arxiv.org/abs/astro-ph/0703111

• Previous message: LARRY KLAES: "SETI bioastro: Discovery of a Bipolar Outflow from 2MASSW J1207334-393254, A 24 Jupiter Mass Br"

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