A&A Supplement series, Vol. 122, May I 1997, 471-481
Received April 11; accepted July 23, 1996
Centauri
J. Kaluzny
- M. Kubiak
-
M. Szymanski
- A. Udalski
-
W. Krzeminski
- M. Mateo
-
K. Stanek
Send offprint request: J. Kaluzny
Warsaw University Observatory, Al. Ujazdowskie 4,
00-478 Warsaw, Poland
e-mail: (jka,mk,msz,udalski)@sirius.astrouw.edu.pl
Carnegie Observatories, Las Campanas Observatory, Casilla 601,
La Serena, Chile
e-mail: wojtek@roses.ctio.noao.edu
Department of Astronomy, University of Michigan, 821 Dennison
Bldg., Ann Arbor, MI 48109-1090, U.S.A.
e-mail: mateo@astro.lsa.umich.edu
Princeton University Observatory, Peyton Hall, Princeton NJ 08544,
U.S.A.
e-mail: stanek@astro.princeton.edu
Three fields located close to the center of the globular cluster
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 P=4.64 day.
Further study of this star can provide direct information about
properties of turnoff stars in 
Cen.
All SX Phe stars and most of eclipsing binaries discovered in our
survey are likely cluster members.
We present V vs. V-I 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 
Cen possesses the largest number of
blue stragglers among all galactic globulars.
keywords: globular clusters: individual: 
Cen -- star:
variables: other -- blue stragglers -- binaries: eclipsing -- HR diagram