Proper motions of young stars in Chamaeleon

II. New kinematical candidate members of Chamaeleon I and II^⋆

¹ Centro de Astrobiología (INTA-CSIC), Departamento de Astrofísica, PO Box 78, 28261 Villanueva de la Cañada Madrid Spain
e-mail: belen@cab.inta-csic.es
² Spanish Virtual Observatory, 2869 Madrid, Spain
³ Suffolk University, Madrid Campus, C/ Valle de la Viña 3, 28003 Madrid, Spain
⁴ European Southern Observatory, Alonso de Córdova 3107, Vitacura, Santiago, Chile
⁵ Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
⁶ Calar Alto Observatory, Centro Astronómico Hispano-Alemán, C/ Jesús Durbán Remón 2-2, 04004 Almería, Spain

Received: 1 February 2013
Accepted: 1 July 2013

Abstract

Context. The Chamaeleon star-forming region has been extensively studied in the last decades. However, most studies have been confined to the densest parts of the clouds. In a previous paper, we analysed the kinematical properties of the spectroscopically confirmed population of the Chamaeleon I and II clouds.

Aims. We want to search for new kinematical candidate members to the Chamaeleon I and II moving groups, extending the studied area beyond the clouds, and to characterize these new populations using available information from public databases and catalogues. We also want to check if the populations of the moving groups are confined to the present dark clouds.

Methods. Kinematic candidate members were initially selected on the basis of proper motions and colours using the Fourth US Naval Observatory CCD Astrograph Catalog (UCAC4). The SEDs of the objects were constructed using photometry retrieved from the Virtual Observatory and other resources, and fitted to models of stellar photospheres to derive effective temperatures, gravity values, and luminosities. Masses and ages were estimated by comparison with theoretical evolutionary tracks in a Hertzprung-Russell diagram. Objects with ages  ≲20 Myr were selected as probable members of the moving groups.

Results. We have identified 51 and 14 candidate members to the Chamaeleon I and II moving groups, respectively, of which 17 and 1, respectively, are classified as probable young stars according to the SED analysis. Another object in Chamaeleon I located slightly above the 1 Myr isochrone is classified as a possible young star. All these objects are diskless stars with masses in the range 0.3 ≲ M/M_⊙ ≲ 1.4 and ages consistent with those reported for the corresponding confirmed members. They tend to be located at the boundaries of or outside the dark clouds, preferably to the north-east and south-east in the case of Chamaeleon I, and to the north-east in the case of Chamaeleon II.

Conclusions. The kinematical population of Chamaeleon I and II could be larger and spread over a larger area of the sky than suggested by previous studies. However, the results of this study should be confirmed with spectroscopic data and more precise kinematic information.