The IMF of open star clusters with Tycho-2

Citation
J. Sanner et M. Geffert, The IMF of open star clusters with Tycho-2, ASTRON ASTR, 370(1), 2001, pp. 87-99
Citations number
60
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Space Sciences
Journal title
ASTRONOMY AND ASTROPHYSICS
ISSN journal
0004-6361 → ACNP
Volume
370
Issue
1
Year of publication
2001
Pages
87 - 99
Database
ISI
SICI code
0004-6361(200104)370:1<87:TIOOSC>2.0.ZU;2-W
Abstract
We studied the fields of nine nearby open star clusters based on the Tycho- 2 catalogue. We determined membership probabilities for the stars in the cl uster fields from the stellar proper motions and used the Tycho-2 photometr y to compute the initial mass function (IMF) of the clusters from the main sequence turn-off point down to approx. 1 M-circle dot. We found IMF slopes ranging from Gamma = -0.69 down to Gamma = -2.27 (when the Salpeter 1955 v alue would be Gamma = -1.35). We also studied the membership of individual stars of special astrophysical interest. In some cases previous results had to be revised. As a by-product, we investigated some general properties of the Tycho-2 catalogue; we confirmed that the Tycho-2 proper motions show o nly marginal deviations from the Hipparcos catalogue. On the other hand, in some regions the completeness of the catalogue seems to decrease at magnit udes brighter than claimed by Hog et al. (2000).