Issue |
Astron. Astrophys. Suppl. Ser.
Volume 122, Number 3, May I 1997
|
|
---|---|---|
Page(s) | 471 - 481 | |
DOI | https://doi.org/10.1051/aas:1997338 | |
Published online | 15 May 1997 |
The optical gravitational lensing experiment. Variable stars in globular clusters*
II. Fields 5139D-F in ω Centauri
1
Warsaw University Observatory, Al. Ujazdowskie 4, 00-478 Warsaw, Poland
2
Carnegie Observatories, Las Campanas Observatory, Casilla 601, La Serena, Chile e-mail: wojtek@roses.ctio.noao.edu
3
Department of Astronomy, University of Michigan, 821 Dennison Bldg., Ann Arbor, MI 48109-1090, U.S.A.
4
Princeton University Observatory, Peyton Hall, Princeton NJ 08544, U.S.A.
Send offprint request to: J. Kaluzny
Received:
11
April
1996
Accepted:
23
July
1996
Three fields located close to the center of the globular cluster
ω Cen were surveyed in a search for variable stars.
We present V-band light curves for 32 periodic variables. This sample
includes 10 SX Phe
stars, 19 eclipsing binaries, and three likely spotted variables
(FK Com or RS CVn type stars). Only 5 of these
variables were previously known (including two objects reported
in Paper I). All SX Phe stars and 8 eclipsing
binaries from our sample belong to blue stragglers.
Five binaries occupy positions on the upper main-sequence
of the cluster and another four are located at the base of the
subgiant branch.
Of particular interest is detection of a
detached binary system with a period day.
Further study of this star can provide direct information about
properties of turnoff stars in ω Cen.
All SX Phe stars and most of eclipsing binaries discovered in our
survey are likely cluster members.
We present V vs.
color-magnitude diagrams for the monitored
fields. A populous group of likely hot subdwarfs as well as
numerous candidates for blue stragglers can be noted in these
diagrams. Our data indicate that ω Cen possesses the largest number of
blue stragglers among all galactic globulars.
Key words: globular clusters: individual: ω Cen / star: variables: other / blue stragglers / binaries: eclipsing / HR diagram
© European Southern Observatory (ESO), 1997