AAS 198th Meeting, June 2001
Session 59. Galactic ISM
Display, Wednesday, June 6, 2001, 10:00am-7:00pm, Exhibit Hall

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[59.17] The NGC\,7538 molecular cloud - a site for high mass protostars

G. Sandell (USRA)

We present high spatial resolution submillimeter maps (850, 800, 450, and 350 \mum) of the molecular cloud south-east of NGC7538 obtained with the James Cerk Maxwell Telescope (JCMT) on Mauna Kea, Hawaii. These maps show filamentary dust ridges extending from and connecting to the three major activity centers (IRS\,1--3, IRS\,11, and IRS\,9) in this high mass star forming cloud. In addition to the three already known star formation centers we also find a fainter extended submmillimeter source near the 20 \mum source IRS\,4 inside the optical HII region. \\

Our high spatial resolution images data resolve the young ultracompact HII region IRS\,1, and show that it is surrounded by a cluster of submillimeter sources, none of which have near or mid infrared counterparts. We also find IRS\,9 to be extended and disk like with a size of 14'' \times 7'' at a position angle of -80\circ. The third activity center, NGC\,7538 H2O (S), is ~ 80'' south of IRS\,1. This submillimeter and far-infrared source is often referred to as IRS\,11. However, our data show that the submillimeter source coincides with the southern H2O and OH masers and is completely unrelated to IRS\,11, which is offset by more than 10'' from the submillimeter source. We resolve NGC\,7538 H2O (S) into an elliptical source of ~ 12'' \times 7'' with a position angle of 55\circ. This cold, deeply embedded submillimeter source is very likely a young high mass protostar with a total mass of more than 100 M\odot.\\

The JCMT is operated by the Joint Astronomy Centre, on behalf of the UK Particle Physics and Astronomy Research Council, the Netherlands Organization for Scientific Research, and the Canadian National Research Council.

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