EDP Sciences Journals List
Advanced Search
Subscriber Authentication Point
Home All issues Volume 388/ 1 Article

Free access article

Issue A&A
Volume 388, Number 1, June II 2002
Page(s) 88 - 99
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20020437



A&A 388, 88-99 (2002)
DOI: 10.1051/0004-6361:20020437

Early-type variables in the Magellanic Clouds

I. $\beta$ Cephei stars in the LMC bar
A. Pigulski and Z. Kolaczkowski

Wroclaw University Observatory, Kopernika 11, 51-622 Wroclaw, Poland

(Received 13 February 2002 / Accepted 21 March 2002)

Abstract
A thorough analysis of the OGLE-II time-series photometry of the Large Magellanic Cloud bar supplemented by similar data from the MACHO database led us to the discovery of three $\beta$ Cephei-type stars. These are the first known extragalactic $\beta$ Cephei-type stars. Two of the three stars are multiperiodic. Two stars have inferred masses of about 10  $M_\odot$ while the third is about 2 mag brighter and at least twice as massive. All three variables are located in or very close to the massive and young LMC associations (LH 41, 59 and 81). It is therefore very probable that the variables have higher than average metallicities. This would reconcile our finding with theoretical predictions of the shape and location of the $\beta$ Cephei instability strip in the H-R diagram. The low number of $\beta$ Cephei stars found in the LMC is another observational confirmation of strong dependence of the mechanism driving pulsations in these variables on metallicity. Follow-up spectroscopic determination of the metallicities in the discovered variables will provide a good test for the theory of pulsational stability in massive main-sequence stars.


Key words: stars: early-type -- stars: oscillations -- stars: variable: other -- stars: abundances -- Magellanic Clouds

Offprint request: A. Pigulski, pigulski@astro.uni.wroc.pl

SIMBAD Objects



© ESO 2002

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.