Dust emission in massive star-forming regions with PRONAOS: the Orion and M17 molecular clouds

The balloon-borne submillimeter instrument PRONAOS has observed one square degree areas towards the Orion and M17 molecular clouds. The 2’ - 3.5’ resolution maps obtained in four wide wavelength bands between 200 microns and 600 microns, exhibit the dust distribution in these regions. We analyze the temperature and spectral index of the dust, and we show the anticorrelation between these two parameters. We derive estimations of the ISM column densities and masses in these regions.