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The young stellar population in the Serpens Cloud Core: An ISOCAM survey

Kaas, A. A. and Olofsson, G. and Bontemps, S. and André, P. and Nordh, L. and Huldtgren, M. and Prusti, T. and Persi, P. and Delgado, A. J. and Motte, F. and Abergel, A. and Boulanger, F. and Burgdorf, M. and Casali, M. M. and Cesarsky, C. J. and Davies, J. and Falgarone, E. and Montmerle, T. and Perault, M. and Puget, J. L. and Sibille, F. (2004) The young stellar population in the Serpens Cloud Core: An ISOCAM survey. Astronomy & Astrophysics, 421 (2). pp. 623-642. ISSN 0004-6361.

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We present results from an ISOCAM survey in the two broad band filters LW2 (5-8.5 μm) and LW3 (12-18 μm) of a 0.13 square degree coverage of the Serpens Main Cloud Core. A total of 392 sources were detected in the 6.7 μm band and 139 in the 14.3 μm band to a limiting sensitivity of ~2 mJy. We identified 53 Young Stellar Objects (YSOs) with mid-IR excess from the single colour index [14.3/6.7], and 8 additional YSOs from the H – K/K – m_(6.7) diagram. Only 32 of these 61 sources were previously known to be YSO candidates. Only about 50% of the mid-IR excess sources show excesses in the near-IR J – H/H – K diagram. In the 48 square arcmin field covering the central Cloud Core the Class I/Class II number ratio is 19/18, i.e. about 10 times larger than in other young embedded clusters such as ρ Ophiuchi or Chamaeleon. The mid-IR fluxes of the Class I and flat-spectrum sources are found to be on the average larger than those of Class II sources. Stellar luminosities are estimated for the Class II sample, and its luminosity function is compatible with a coeval population of about 2 Myr which follows a three segment power-law IMF. For this age about 20% of the Class IIs are found to be young brown dwarf candidates. The YSOs are in general strongly clustered, the Class I sources more than the Class II sources, and there is an indication of sub-clustering. The sub-clustering of the protostar candidates has a spatial scale of 0.12 pc. These sub-clusters are found along the NW-SE oriented ridge and in very good agreement with the location of dense cores traced by millimeter data. The smallest clustering scale for the Class II sources is about 0.25 pc, similar to what was found for ρ Ophiuchi. Our data show evidence that star formation in Serpens has proceeded in several phases, and that a “microburst” of star formation has taken place very recently, probably within the last 10^5 yrs.

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Davies, J.0000-0002-4108-4357
Additional Information:© 2004 ESO. Article published by EDP Sciences. Received 1 December 2003; Accepted 18 March 2004; Published online 22 June 2004. Based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, The Netherlands and the United Kingdom) and with participation of ISAS and NASA. The authors wish to thank Carlos Eiroa for stimulating discussions and helpful comments. We also thank an anonymous referee for comments that helped us improve the paper. The ISOCAM data presented in this paper were reduced using "CIA", a joint development by the ESA Astrophysics Division and the ISOCAM Consortium led by the ISOCAM PI, C. Cesarsky, Direction des Sciences de la Matière, C.E.A., France. The near-IR data presented in this paper were obtained with the ARcetri Near InfraRed CAmera ( ARNICA) at the Nordic Optical Telescope in 1996, and Carlo Baffa, Mauro Sozzi, Ruggero Stanga and Leonardo Testi from the ARNICA team are acknowledged for the instrument support. The Nordic Optical Telescope is operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. This publication made use of the SIMBAD database, operated at CDS, Strasbourg, France, and data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. Financial support from the Swedish National Space Board is acknowledged.
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Swedish National Space Board (SNSB)UNSPECIFIED
Subject Keywords:stars: formation - stars: pre-main-sequence - stars: luminosity function, mass function - stars: low-mass, brown dwarfs - ISM: individual objects: Serpens Cloud Core
Issue or Number:2
Record Number:CaltechAUTHORS:20180214-160755588
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Official Citation:The young stellar population in the Serpens Cloud Core: An ISOCAM survey. A. A. Kaas, G. Olofsson, S. Bontemps, P. André, L. Nordh, M. Huldtgren, T. Prusti, P. Persi, A. J. Delgado, F. Motte, A. Abergel, F. Boulanger, M. Burgdorf, M. M. Casali, C. J. Cesarsky, J. Davies, E. Falgarone, T. Montmerle, M. Perault, J. L. Puget and F. Sibille A&A, 421 2 (2004) 623-642. DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:84839
Deposited By: Tony Diaz
Deposited On:15 Feb 2018 00:23
Last Modified:09 Mar 2020 13:18

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