Surface density of the young cluster IC 348 in the Perseus molecular cloud

¹ Observatoire Astronomique de Strasbourg, 67000 Strasbourg, France e-mail: cambresy@astro.u-strasbg.fr
² Department of Astrophysics Astronomy & Mechanics, Faculty of Physics, University of Athens, 15783 Athens, Greece
³ Institute for Astronomy and Astrophysics, National Observatory of Athens, PO Box 20048, 118 10 Athens, Greece

Received: 1 August 2005
Accepted: 1 September 2005

Abstract

The IC 348 young star cluster contains more than 300 confirmed members. It is embedded in the Perseus molecular cloud, making any clustering analysis subject to an extinction bias. In this work, we derive the extinction map of the cloud and revisit the content of IC 348 through a statistical approach that uses the 2MASS data. Our goal was to address the question of the completeness of IC 348 and of young clusters in general. We performed a combined analysis of the star color and density in this region, in order to establish the surface density map of the cluster. We reached the conclusion that IC 348 has structures up to from the cluster center, and we estimate that about 40 members brighter than mag are still unidentified. Although we cannot use our statistical method to identify these new members individually, the surface density map gives a strong indication of their actual location. They are distributed in the outer regions of the cluster, where very few dedicated observations have been made so far, which is probably why they escaped previous identification. In addition, we propose the existence of a new embedded cluster associated to the infrared source MSX 6C G160.2784-18.4216, about south of IC 348.