Submillimeter mapping and analysis of cold dust condensations in the Orion M42 star-forming complex

We present here the continuum submillimeter maps of the molecular cloud around the M42 Nebula in the Orion region. These have been obtained in four wavelength bands (200, 260, 360, and 580 mum) with the Programme National d'Observations Submillimetriques 2 m balloon-borne telescope. The area covered is 7 pc wide (50' at a distance of 470 pc) with a spatial resolution of about 0.4 pc. Thanks to the high sensitivity to faint surface brightness gradients, we have found several cold condensations, with temperatures ranging from 12 to 17 K, within 3 pc of the dense ridge. The statistical analysis of the temperature and spectral index spatial distribution shows an evidence of an inverse correlation between these two parameters. Being invisible in the IRAS 100 mum survey, some cold clouds are likely to be the seeds for future star formation activity going on in the complex. We estimate their masses, and we show that two of them have masses higher than their Jeans masses and may be gravitationally unstable.