Nebula — Temperature - spectral index inverse correlation in several regions

We have mapped with the French submillimeter balloon-borne telescope ProNaOS the thermal emission of the dust in the M42 Orion Nebula. The map obtained is 50' by 40' with an angular resolution of about 3' in the four efficient wavelengths 200 µm, 260 µm, 360 µm and 580 µm. The temperature and index we obtain are highly variable within the studied region: the temperature varies from 12 K to 70 K, and the spectral index from 1.1 to 2.2. The statistical analysis of the temperature and spectral index spatial distribution in this region, as well as in the other regions mapped by ProNaOS, shows an evidence of an inverse correlation between these two parameters. We deduce the column densities of gas and the masses. Being invisible in the IRAS 100 µm survey, some cold clouds are likely to be the seeds for future star formation activity going on in the complex.