Stars and brown dwarfs in the σ Orionis cluster: the Mayrit catalogue *
Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany e-mail: email@example.com
Accepted: 22 October 2007
Context.The young σ Orionis cluster is an indispensable basis for understanding the formation and evolution of stars, brown dwarfs, and planetary-mass objects. Our knowledge of its stellar population is, however, incomplete.
Aims.I present the Mayrit catalogue, which comprises most of the stars and high-mass brown dwarfs in the cluster.
Methods.The basis of this work is an optical-near infrared correlation between the 2MASS and DENIS catalogues in a circular area of radius 30 arcmin centred on the OB-type binary σ Ori AB. The analysis is supported by a bibliographic search of confirmed cluster members with features of youth and by additional X-ray, mid-infrared, and astrometric data.
Results.I list 241 σ Orionis stars and brown dwarfs with known features of youth, 97 candidate cluster members (40 are new), and 115 back- and foreground sources in the survey area. The 338 cluster members and member candidates constitute the Mayrit catalogue.
Conclusions.This catalogue is a suitable input for studying the spatial ditribution, multiplicity, properties and frequency of discs, and the complete mass function of σ Orionis.
Key words: astronomical data bases: miscellaneous / stars: low-mass, brown dwarfs / Galaxy: open clusters and associations: individual: σ Orionis
© ESO, 2008