A revisit to the region of Collinder 132 using Carte du Ciel and Astrographic Catalogue plates

R. B. ORELLANA, M. S. DE BIASI, I. H. BUSTOS FIERRO AND J. H. CALDERÓN

ASTRONOMY AND ASTROPHYSICS

EDP SCIENCES S A

Lugar: Paris; Año: 2010 vol. 521 p. 390 - 398

0004-6361

Aims. Based on stellar positions and proper motions, we aim to re-analyse the region of the controversial open cluster Collinder 132.Methods. We have developed a model which analyses the proper motion distribution and the stellar density to find moving groups.The astrometric data were obtained from four Carte du Ciel (CdC) and one Astrogaphic Catalogue (AC) plates of the CórdobaAstronomical Observatory collection (Argentina).Results. We detected an open cluster from the field stars and calculated the mean proper motion and the membership probabilitiesof the region’s stars. We report new coordinates of its centre alfac = 108.°347, deltac = -31.°011, the components of mean proper motion (mualfa cosdelta) = -2.62 ± 0.44 mas/yr, (mudelta) = 4.79 ± 0.88 mas/yr. Thirteen stars are astrometric members giving a value of 20´ for thecluster angular diameter. Six stars fulfil the astrometric and photometric criteria for being cluster members and locate the cluster at360 pc from the Sun. We propose a simple model for the analysis of the proper motion distribution of an association. We report thecomponents of the association mean proper motion (mualfa cosdelta) = -1.38±0.14 mas/yr, (mudelta)= 2.26±0.16 mas/yr.We found 149 astrometricmembers, 11 of which have reliable photometric data that locate them betweeen 417 and 660 pc from the Sun.