Document 
| Abstract | PDF (1.37 MB) | PS (1.40 MB) | References | HTML | Online Material | Tables at CDS | Simbad Objects | NASA ADS Abstract Service |
Free access article
A&A 421, 623-642 (2004)
DOI: 10.1051/0004-6361:20035775
The young stellar population in the Serpens Cloud Core: An ISOCAM survey
A. A. Kaas1, 2, G. Olofsson2, S. Bontemps3, 2, P. André4, L. Nordh2, M. Huldtgren2, T. Prusti5, P. Persi6, A. J. Delgado7, F. Motte4, A. Abergel8, F. Boulanger8, M. Burgdorf9, M. M. Casali10, C. J. Cesarsky4, J. Davies11, E. Falgarone12, T. Montmerle13, M. Perault12, J. L. Puget8 and F. Sibille141 Nordic Optical Telescope, Apdo 474, 38700 Santa Cruz de La Palma, Spain
2 Stockholm Observatory, Roslagstullsbacken 21, 10691 Stockholm, Sweden
3 Observatoire de Bordeaux, BP 89, 33270 Floirac, France
4 Service d'Astrophysique, CEA Saclay, 91191 Gif-sur-Yvette, France
5 Research and Scientific Support Department of ESA, Postbus 229, 2200 AG Noordwijk, The Netherlands
6 Instituto Astrofisica Spaziale e Fisica Cosmica, CNR, Rome, Italy
7 Instituto de Astrofísica de Andalucia, Granada, Spain
8 IAS, Université Paris XI, 91405 Orsay, France
9 SIRTF Science Center, California Institute of Technology, 220-6, Pasadena, CA 91125
10 Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK
11 Joint Astronomy Centre, 660 N. A'Ohoku Place, University Park, Hilo, HI 96720, USA
12 ENS Radioastronomie, 24 Rue Lhomond, 75231 Paris, France
13 Laboratoire d'Astrophysique de Grenoble, 38041 Grenoble Cedex, France
14 Observatoire de Lyon, 69230 Saint Genis Laval, France
(Received 1 December 2003 / Accepted 18 March 2004)
Abstract
We present results from an ISOCAM survey in the two broad band
filters LW2 (5-8.5
m) and LW3 (12-18
m) of a 0.13 square degree
coverage of the Serpens Main Cloud Core. A total of 392 sources were
detected in the 6.7
m band and 139 in the 14.3
m 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-m6.7 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
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
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.
Key words: stars: formation -- stars: pre-main-sequence -- stars: luminosity function, mass function -- stars: low-mass, brown dwarfs -- ISM: individual objects: Serpens Cloud Core
Offprint request: A. A. Kaas, akaas@not.iac.es
SIMBAD Objects
Tables at the CDS
© ESO 2004