Issue |
A&A
Volume 447, Number 3, March I 2006
|
|
---|---|---|
Page(s) | 915 - 919 | |
Section | Galactic structure, stellar clusters, and populations | |
DOI | https://doi.org/10.1051/0004-6361:20040297 | |
Published online | 10 February 2006 |
A method of open cluster membership determination
Abastumani Astrophysical Observatory, Georgian Academy of Sciences, Georgia e-mail: todua@hotmail.com
Received:
18
February
2004
Accepted:
30
July
2005
A new method for the determination of open cluster membership based
on a cumulative effect is proposed. In the field of a plate the
relative x and y coordinate positions of each star with respect
to all the other stars are added. The procedure is carried
out for two epochs t1 and t2 separately, then one sum is
subtracted from another. For a field star the differences in its relative coordinate
positions of two epochs will be accumulated. For a cluster
star, on the contrary, the changes in relative positions of cluster
members at t1 and t2 will be very small. On the histogram of sums the
cluster stars will gather to the left
of the diagram, while the field stars will form a tail to the right.
The procedure allows us to efficiently discriminate one group from
another. The greater the distance between t1 and t2 and the more
cluster stars present, the greater is the effect. The
accumulation method does not require reference stars,
determination of centroids and modelling the distribution of
field stars, necessary in traditional methods. By the proposed method 240
open clusters have been processed, including stars up to . The membership
probabilities have been calculated and compared to those obtained by the most
commonly used Vasilevskis-Sanders method. The similarity of the results acquired the
two different approaches is satisfactory for the majority
of clusters.
Key words: galaxies: stars clusters / methods: analytical
© ESO, 2006
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