N. Reid et W. Freedman, THE RR LYRAE POPULATION OF THE LMC .1. THE IMMEDIATE ENVIRONMENT OF NGC-2210, Monthly Notices of the Royal Astronomical Society, 267(4), 1994, pp. 821-839
We present results of a CCD-based survey for RR Lyraes in various regi
ons of the Large Magellanic Cloud (LMC). This first study is part of a
long-term programme which aims to use RR Lyraes to map the distributi
on and kinematics of the oldest stellar population in the LMC. Our dat
a cover a 15 x 15 arcmin2 field in the vicinity of the LMC globular NG
C 2210. We have identified 44 moderate-amplitude variable stars, of wh
ich 31 were known from the previous surveys summarized by Hazen & Neme
c. Our field of view includes a further eight stars from the latter su
rvey, only one of which - a low-amplitude variable near the cluster ce
ntre - is confirmed as variable by our observations. At least 27 of th
e variables are RR Lyraes, the majority of which clearly are associate
d with NGC 2210. The mean magnitude of the RR Lyraes most distant from
the cluster centre, which we suggest as likely LMC members, is 0.1 ma
g fainter than that of the cluster variables. If the field stars have
the same mean abundance as NGC 2210, this implies that the cluster is
approximately 2 kpc in front of the LMC, and, allowing for the tilt of
the LMC as a whole, we derive a distance modulus of 18.3 to 18.5 to t
he centre of the Bar of the LMC.