Journal Article

A search for SX Phe stars among <i>Kepler</i> δ Scuti stars

L. A. Balona and J. M. Nemec

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 426, issue 3, pages 2413-2418
Published in print November 2012 | ISSN: 0035-8711
Published online November 2012 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2012.21957.x
A search for SX Phe stars among Kepler δ Scuti stars

More Like This

Show all results sharing this subject:

  • Astronomy and Astrophysics

GO

Show Summary Details

Preview

The SX Phe stars are Population II pulsating variables lying below the horizontal branch. Their pulsation characteristics resemble those of δ Sct stars. Since old stars in the Kepler field situated in the thick disc or halo are likely to have kinematics different from δ Sct stars, we use proper motions and tangential velocities to search for possible SX Phe variables among 1424 Kepler δ Scuti stars. Tangential velocities derived from distances obtained from the photometric calibration in the Kepler input catalogue appear to be an effective method of separation between thin-disc and thick-disc/halo stellar populations. Using this method, 34 candidate SX Phe stars are identified, eight of which are located more than 0.5 kpc above the galactic plane. We find that the light curves of these stars cannot be distinguished from those of normal δ Scuti stars. It is generally thought that field SX Phe stars have high amplitudes and only one or two frequencies, but such light curves are rare among the candidate SX Phe stars in the Kepler field. We suggest that the relatively high amplitudes, which until now have been a defining characteristic of field SX Phe stars, are merely a selection effect. This supports the recent finding of several low-amplitude multiperiodic SX Phe stars in some globular clusters.

Keywords: stars: kinematics and dynamics; stars: oscillations; stars: variables: δ Scuti

Journal Article.  3813 words.  Illustrated.

Subjects: Astronomy and Astrophysics

Full text: subscription required

How to subscribe Recommend to my Librarian

Users without a subscription are not able to see the full content. Please, subscribe or login to access all content.