The stellar content of OMC 2/3^*

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

Corresponding author: M. Nielbock, mnielboc@eso.org

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 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.