干旱区生态环境知识资源中心

A maximum entropy method (MEM) is used to construct an IRAS image of the M17 nebula at 12 mum from the raw IRAS data; no prior information about the structure in the field is given to the maximum entropy routines. The overall emission seen in this image agrees well with that observed at radio wavelengths. The 12-mum flux density of the M17SW region, as measured from the data, suggests the presence of a hot dust component at T(d) = 108 +/- 5 K. The distribution of the emission suggests either that the hot dust is mixed with the ionized gas of the H II region, or that it lies in the photo-dissociation region (PDR), and probably represents a population of PAHs. The data are compared with the dust model of Desert, Boulanger & Puget, which confirms that the 12-mum emission is not coming from the denser molecular cloud regions.