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M. Kassis, L. K. Deutsch (IAR-BU), J. L. Hora, G. G. Fazio (CFA), W. F. Hoffmann (Steward Obs./U. Arizona), A. Dayal (IPAC/Caltech)
We obtained diffraction limited mid-infrared images of the Omega Nebula (M17) using MIRAC2 on the NASA IRTF in order to study the formation of massive stars, the possible role played by circumstellar disks, and the structure and content of the photodissociation regions (PDRs). M17 is a massive and luminous molecular cloud complex exhibiting triggered star formation and suggested to harbor massive stars in their earliest stages of stellar evolution. Large area mosaics (2'x1.5') at 9.8, 10.53, 11.7, and 20.6\mum map a portion of the M17 south west PDR. This region may only be observed at infrared and radio wavelengths due to large extinction by a foreground cloud. Our observations map emission from ionized gas at [SIV] 10.52\mum, the hydrocarbon emission feature at 11.2\mum, and dust at 9.8 and 20.6\mum. The current observations improve upon previous lower resolution mid-infrared studies. The emission towards the ultra-compact HII region M17-UC1 is resolved into two components: 1) a bright point source coincident with near infrared and radio emission attributed to M17-UC1, and 2) an extended source of comparable intensity which is resolved at all wavelengths. The narrow band 11.7\mum observations shows enhanced emission in M17-UC1 relative to the extended source which lies a few arcseconds to the south-west, and the enhanced emission is attributed to the hydrocarbon feature at 11.2\mum. Comparison of our 11.7\mum and 10.53\mum maps indicates that the hydrocarbon emission has a similar shape to, but is spatially offset from, the arc-shaped ionization front. High-resolution color temperature and dust opacity maps calculated from the continuum measurements will also be presented, and the implications of our results will be discussed.
The author(s) of this abstract have provided an email address for comments about the abstract: mkassis@bu.edu