EDP Sciences Journals List
Advanced Search
Subscriber Authentication Point
Home All issues Volume 505/1 Article
Free access article

Issue A&A
Volume 505, Number 1, October I 2009
Page(s) 239 - 248
Section Stellar structure and evolution
DOI http://dx.doi.org/10.1051/0004-6361/200912457
Published online 09 July 2009

A&A 505, 239-248 (2009)
DOI: 10.1051/0004-6361/200912457

Interpreting the line-profile variations of subdwarf B pulsators: the case of PG 1336-018 (NY Virginis)

M. Vučković1, R. H. Østensen1, C. Aerts1, 2, J. H. Telting3, U. Heber4, and R. Oreiro1

1  Institute for Astronomy, K. U. Leuven, Leuven, Belgium
    e-mail: maja.vuckovic@ster.kuleuven.be
2  Department of Astrophysics, Radboud University, Nijmegen, The Netherlands
3  Nordic Optical Telescope, Santa Cruz de La Palma, Spain
4  Dr. Remeis-Sternwarte, Universität Erlangen-Nürnberg, Bamberg, Germany

Received 09 May 2009 / Accepted 25 June 2009

Abstract
Aims. We analyze the high-resolution time-resolved VLT/UVES spectra of PG 1336-018, a rapidly pulsating subdwarf B (sdB) primary in a close orbit with an M5 companion, with the aim to detect the pulsational signal of the primary in line-profile variations.
Methods. After removing the dominant radial-velocity component inherent to the orbital motion and taking only out-of-eclipse data we computed cross-correlation functions (CCFs) for each individual spectrum and assumed these to approximate the average line profile. We computed predictions of line-profile variations for pulsating sdB stars and present their diagnostic value for mode identification.
Results. We detect the pulsation mode at 5435 $\mu$Hz in the line-profile variations of the CCFs which allows us to characterize the detected pulsation mode of PG 1336-018 .
Conclusions. We model the pulsational perturbations of synthetic spectra for a star with physical parameters like PG 1336-018  and confront them with the observed spectra. We find that low order Balmer lines can be used as diagnostic tool to identify pulsation modes. A detailed line-profile analysis of the perturbed time-series spectra excludes the $\ell$ = |m| = (3,3), (1,0), (2,1) and (2,0) modes, but does not allow a unique mode identification among the radial or sectoral dipole or quadrupole modes.


Key words: subdwarfs -- binaries: eclipsing -- stars: variables: general -- line: profiles -- stars: oscillations -- stars: individual: PG 1336-018



© ESO 2009


What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.
  • If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
  • You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
  • You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.