Issue |
Astron. Astrophys. Suppl. Ser.
Volume 144, Number 2, June I 2000
|
|
---|---|---|
Page(s) | 227 - 233 | |
DOI | https://doi.org/10.1051/aas:2000209 | |
Published online | 15 June 2000 |
First results of a photometric and astrometric study of the globular cluster M 71 (NGC 6838)
1
Sternwarte der Universität Bonn, Auf dem Hügel 71, D-53121 Bonn, Germany
2
Observatoire de Bordeaux, URA 352 CNRS/INSU, BP. 89, F-33270 Floirac, France
Send offprint request to: M. Geffert
Received:
7
September
1998
Accepted:
7
March
2000
We present the first results of a photometric and astrometric
investigation of stars in the region
of the globular cluster M 71 (NGC 6838). Using wide field
CCD observations we determined B and V magnitudes
of 4450 stars up to a limiting magnitude
of V
≤ 18.5 mag.
Relative proper motions were used to derive membership
probabilities for stars with around the centre
of M 71. Our colour-magnitude diagram
(CMD) of 320 probable cluster members
reaches down to V = 18. A well defined red giant bump
- for the first time seen in M 71 - could be detected in our CMD.
From isochrone fitting we find M 71
metal poorer and older than previously assumed.
Four faint variable stars were confirmed
to be members of M 71. Moreover, we detected 13 blue
stragglers among our cluster members.
Key words: astrometry / (stars:) blue stragglers / (Galaxy:) globular clusters: individual: M 71
© European Southern Observatory (ESO), 2000