A&A 425, 553-567 (2004)
Sharpless 170 and the surrounding interstellar mediumR. S. Roger1, W. H. McCutcheon2, C. R. Purton1 and P. E. Dewdney1
1 National Research Council Canada, Herzberg Institute of Astrophysics, Dominion Radio Astrophysical Observatory, Penticton, BC V2A 6J9, Canada
2 Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
(Received 18 September 2003 / Accepted 17 June 2004 )
Sharpless 170 is a diffuse HII region ionized by a single main sequence O-star located near the periphery of a small dense molecular cloud at a distance of ~2 kpc. We describe wide-field observations of the region in the radio continuum, in HI and CO-lines, and in the far-infrared which delineate the major ionized, atomic, molecular and dust components of the gas affected by the exciting star. From the thermal continuum emission we estimate the mass of ionized gas at ~350 within a radius of ~7 pc. The HI ( 21 cm) and far-infrared observations show an extended low-density atomic component, of ~1000 , within an irregular boundary surrounding the ionized gas of mean radius ~10 pc. Mean densities in the HI and HII are similar, in the range 9-16 nucleons cm -3. CO emission shows a molecular cloud of ~1150 within an area 6 pc 4 pc with densities ~2000 nucleons cm -3. A compact infrared component coincides with the cloud. The exciting star is located on the near side of the cloud, just inside the southern periphery.
Key words: stars: individual: BD +63 2093p (AG+64 1262) -- Galaxy: open clusters and associations: individual: Sh 2-170 -- radio continuum: ISM -- radio lines: ISM -- infrared: ISM
© ESO 2004