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Issue A&A
Volume 408, Number 1, September II 2003
Page(s) 245 - 256
Section Formation, structure and evolution of stars
DOI http://dx.doi.org/10.1051/0004-6361:20030961



A&A 408, 245-256 (2003)
DOI: 10.1051/0004-6361:20030961

The stellar content of OMC 2/3

M. Nielbock1, 2, R. Chini1 and S. A. H. Müller1

1  Astronomisches Institut der Ruhr-Universität Bochum, Universitätsstrasse 159/NA 7, 44780 Bochum, Germany
2  SEST, European Southern Observatory, Alonso de Cordova 3107, Santiago, Chile

(Received 25 April 2003 / Accepted 17 June 2003)

Abstract
We have revisited the stellar content of OMC 2 and OMC 3 by means of MIR imaging and NIR photometry; in addition, we have extended the existing (sub)mm maps by a huge $1200\,\mu$m map obtained with SIMBA showing new sources and filamentary features for the first time at that wavelength. The MIR data reveal 43 new sources at  N and  Q which are partly associated with dense condensations at millimetre wavelengths. Six close binary sources could be resolved at locations where existing (sub)mm maps only show single emission peaks; three of them are classified as early (B-type) systems, one of them is compatible with type K while the remaining two seem to be T Tauri stars. Furthermore, the MIR images indicate the existence of separate circumstellar discs in the K-binary system. NIR colour-colour and colour-magnitude diagrams obtained from 2MASS data are examined to explore the physical properties of the sources and to derive the distribution of  J luminosities. There is a clear decrease in luminosity and thus in stellar mass when going from South to North. Likewise, there is an anti-correlation between Class I and II objects in both regions: while OMC 2 contains twice as much Class II objects compared to Class I, the situation is reversed in OMC 3.


Key words: ISM: dust -- stars: circumstellar matter, formation

Offprint request: M. Nielbock, mnielboc@eso.org

SIMBAD Objects



© ESO 2003


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