A deep wide-field optical survey in the young open cluster Collinder 359

¹ Department of Physics & Astronomy, University of Leicester, University Road, Leicester LE1 7RH, UK e-mail: nl41@star.le.ac.uk
² Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany
³ Laboratoire d'Astrophysique, Observatoire de Grenoble, BP 53, 38041 Grenoble Cedex 9, France e-mail: [Jerome.Bouvier;Willem-Jan.DeWit]@obs.ujf-grenoble.fr
⁴ Physics and Astronomy Department, Vanderbilt University, 1807 Station B, Nashville, TN 37235, USA e-mail: david.j.james@vanderbilt.edu
⁵ INAF, Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Florence, Italy e-mail: palla@arcetri.astro.it
⁶ University of Exeter, School of Physics, Stocker Road, Exeter EX4 4QL, UK e-mail: mjm@aip.de; mjm@astro.ex.ac.uk
⁷ Canada-France-Hawaii Telescope Corp., Kamuela, HI 96743, USA e-mail: jcc@cfht.hawaii.edu

Received: 26 August 2005
Accepted: 30 December 2005

Abstract

We present the first deep, optical, wide-field imaging survey of the young open cluster Collinder 359, complemented by near-infrared follow-up observations. This study is part of a large programme aimed at examining the dependence of the mass function on environment and time. We have surveyed 1.6 square degrees in the cluster, in the I and z filters, with the CFH12K camera on the Canada-France-Hawaii 3.6-m telescope down to completeness and detection limits in both filters of 22.0 and 24.0 mag, respectively. Based on their location in the optical (, I) colour–magnitude diagram, we have extracted new cluster member candidates in Collinder 359 spanning 1.3-0.03 , assuming an age of 60 Myr and a distance of 450 pc for the cluster. We have used the 2MASS database as well as our own near-infrared photometry to examine the membership status of the optically-selected cluster candidates. Comparison of the location of the most massive members in Collinder 359 in a (, V) diagram with theoretical isochrones suggests that Collinder 359 is older than α Per but younger than the Pleiades. We discuss the possible relationship between Collinder 359 and IC 4665 as both clusters harbour similar parameters, including proper motion, distance, and age.