Issue |
Astron. Astrophys. Suppl. Ser.
Volume 128, Number 2, March I 1998
|
|
---|---|---|
Page(s) | 255 - 264 | |
DOI | https://doi.org/10.1051/aas:1998139 | |
Published online | 15 March 1998 |
Membership determination of stars using proper motions in the region of the open cluster M 11 *
1
Shanghai Observatory, Chinese Academy of Sciences, Shanghai 200030, China
2
CCAST(World Laboratory), P.O. Box 8730, Beijing 100080, China
Send offprint request to: Cheng-gang Su
Received:
20
January
1997
Accepted:
26
May
1997
Relative proper motions of 872 stars in the open cluster M 11
region are reduced using 10 plate pairs taken over time baselines
of years with the double astrograph telescope of Shanghai
Observatory. The scale is
. The plates were measured with
the PDS machines in the Purple Mountain Observatory in Nanjing
and the Institute of Technology and Communication in Luoyang, China.
The average proper motion accuracy is about 1.1 mas/yr with
of the data better than 1 mas/yr.
Membership probabilities of 785 stars within 25′ centred on M 11
are determined based on their proper motions. The method used
is suggested by Su et al. (1995) with some improvements of Zhao & He (1990), in which the space distribution and magnitude
dependencies for cluster stars are taken into account.
The results are significantly good. The total integrated membership
probabilities for all these stars is 547 and the number of stars
with probabilities higher than 0.7 is 541. It can be found after
the membership determination that there exists mass segregation
in M 11. Some comparisons and discussion are also given.
Key words: star cluster: open / individual: M 11 / proper motions: membership determination / dynamics
© European Southern Observatory (ESO), 1998