Letter to the Editor

Protostellar clusters in intermediate mass (IM) star forming regions

¹ Observatorio Astronómico Nacional (OAN), Apdo. 112, 28803 Alcalá de Henares (Madrid), Spain e-mail: a.fuente@oan.es
² Laboratoire d'Astrophysique de l'Observatoire de Grenoble, BP 53, 38041 Grenoble Cedex 9, France
³ Institute de Radioastronomie Millimétrique, 300 rue de la Piscine, 38406 St Martin d'Hères Cedex, France
⁴ INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
⁵ Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 0213
⁶ Department of Physics and Astronomy, University of Victoria, Victoria, BC V8P 1A1, Canada
⁷ National Research Council of Canada, Herzberg Institute of Astrophysics, 5071 West Saanich Road, Victoria, BC V9E 2E7, Canada
⁸ Leiden Observatory, PO Box 9513, 2300 RA Leiden, The Netherlands
⁹ Max-Planck-Institut fur Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany

Received: 14 February 2007
Accepted: 29 March 2007

Abstract

Context.The transition between the low density groups of T Tauri stars and the high density clusters around massive stars occurs in the intermediate-mass (IM) range (). High spatial resolution studies of IM young stellar objects (YSO) can provide important clues to understand the clustering in massive star forming regions.

Aims.Our aim is to search for clustering in IM Class 0 protostars. The high spatial resolution and sensitivity provided by the new A configuration of the Plateau de Bure Interferometer (PdBI) allow us to study the clustering in these nearby objects.

Methods.We have imaged three IM Class 0 protostars (Serpens-FIRS 1, IC 1396 N, CB 3) in the continuum at 3.3 and 1.3 mm using the PdBI. The sources have been selected with different luminosity to investigate the dependence of the clustering process on the luminosity of the source.

Results.Only one millimeter (mm) source is detected towards the low luminosity source Serpens-FIRS 1. Towards CB 3 and IC1396 N, we detect two compact sources separated by ~0.05 pc. The 1.3 mm image of IC 1396 N, which provides the highest spatial resolution, reveal that one of these cores is splitted in, at least, three individual sources.