Issue |
A&A
Volume 416, Number 1, March II 2004
|
|
---|---|---|
Page(s) | 125 - 136 | |
Section | Galactic structure, stellar clusters, and populations | |
DOI | https://doi.org/10.1051/0004-6361:20034238 | |
Published online | 26 February 2004 |
Proper motion surveys of the young open clusters Alpha Persei and the Pleiades*
Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ, UK
Corresponding author: N. R. Deacon, nd@roe.ac.uk
Received:
28
August
2003
Accepted:
28
October
2003
In this paper we present surveys of two open clusters using photometry
and accurate astrometry from the SuperCOSMOS microdensitometer. These
use plates taken by the Palomar Oschin Schmidt Telescope giving a wide
field ( from the cluster centre in both cases),
accurate positions and a long time baseline for the proper
motions. Distribution functions are fitted to proper motion vector
point diagrams yielding formal membership probabilities. Luminosity and
mass functions are then produced along with a catalogue of high
probability members. Background star contamination
limited the depth of the study of Alpha Per to
. Due to this the
mass function found for this cluster could only be fitted with a power
law (
) with
. However with the
better seperation of the Pleiades' cluster proper motion from the
field population results were obtained down to
. As the mass function
produced for this cluster extends to lower masses it is possible to
see the gradient becoming increasingly shallow. This mass function is
well fitted by a log normal distribution.
Key words: astrometry / stars: low mass, brown dwarfs / Galaxy: open clusters and associations: individual: Alpha Per, Pleiades
© ESO, 2004
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