Proper motions and CCD-photometry of stars in the region of the open cluster Trumpler 2
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/ Abstract
The results of the complex study of galactic open cluster Trumpler2 are presented.The positions of approximately 3000 stars up to the limit magnitude B ∼ 16.25 mag in the area 80 ′ × 80 ′ around the cluster were measured in order to obtain the proper motions. Measurements of star positions on 6 plates with the maximal epoch difference of 63 years were taken by means of the automated measuring complex ”Fantasy”. The root-mean error of the relative proper motions is 4.2 mas yr −1 . The catalogue of BV magnitudes of all the stars in the investigated area was compiled. Astrometric selection of the cluster members within the region of R < 16 ′ from the center of the cluster was made by means of the W.Sanders method(1971). In that field 192 stars were found to have the individual membership probability greater then 85%, 148 of them are situated within the ±3σB−V band around the main sequence (MS) of the cluster. They are considered to be cluster members by two criteria. The U-B∼B-V diagram plotted for the astrometrical cluster members by the data taken from the Washington catalogue of the UBV photometry in the galactic cluster fields (Hoag et al. 1961) has made it possible to redefine the value of the color excess E(B-V)= 0. m 40 instead of previously published values ranged from 0. m 30 to 0. m 34. The superposition of the MS of the cluster with the ZAMS Schmidt-Kaler (1965) for thus accepted E(B-V) leads to the coincidence at the value of the apparent distance module (V − MV ) = 10.50 which corresponds to the distance r = 725pc. The luminosity and mass functions of the Trumpler2 were constructed and the value of the slope ( = −1.90±0.22) was determined. The cluster age of 8.913×10 7 yr was determined on the base of Girardi et al. (2000) isochrone grid. Correspondent to this age the turn-off
Journal: Astronomy and Astrophysics