Friday, 21st November at 2.00pm at the JAC

ABSTRACT: We have been studying the impact of HII regions on star formation and their associated molecular clouds in a sample of 10 HII regions. We use the James Clerk Maxwell Telescope to make 7x7 arcmin maps in 12CO(2-1), which we use to investigate the structure of each cloud and to identify the individual clumps and dense cores within each clump. We then make single-point observations in 13CO(2-1) and CS(5-4) at the brightest 12CO(2-1) peak in each clump to measure the physical properties of the gas. We calculate and measure densities, temperatures, clump masses, peak velocities and line widths.

We have identified two condensed regions (A and B) associated with the S175 HII region. S175A is adjacent to the ionized gas fronts and is expected to be affected by the HII region, while S175B is too distant to be disturbed. We compare the structure and gas properties of these two regions to investigate how the molecular gas has been affected by the HII region. Noticeably, S175A has a narrow structure and is highly fragmented. S175B seems to be more uniform; identified clumps within this region lie on extended uniform CO emission. S175B contains a very active sub-region with strong evidence of outflow. We discuss the various factors that cause such differences within the observed regions.