2009/03/24 by Mohaddesseh Azimlu, M. Azimlu, Michel Fich +1
Physics and Astronomy · #Astrophysics #Astrophysics and Star Formation Studies #Atomic and Molecular Physics #Front (military) #Geometry #H II region #Ion #Ionization #James Clerk Maxwell Telescope #Line (geometry) #Meteorology #Molecular cloud #Outflow #Physics #Star formation #Stars #Stellar, planetary, and galactic studies #Turbulence #astro-ph.SR
paper · pdf · doi:10.1088/0004-6256/137/6/4897
33 pages, 11 figures, 6 tables, accepted for publication in Astronomical Journal
arxiv created 2009/03/24 · openalex publication_date 2009/05/04 · arxiv updated 2015/05/13 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
We are studying the impact of H ii regions on star formation in their associated molecular clouds. In this paper, we present James Clerk Maxwell Telescope R x A molecular line observations of S175 and environs. This is the first within a sample of 10 H ii regions and their surrounding molecular clouds selected for our study. We first make 7' × 7' maps in 12 CO(2–1), which are used to investigate the structure of the cloud and to identify individual clumps. Single point observations were made in 13 CO(2–1) and CS(5–4) at the peak of the 12 CO(2–1) emission within each clump in order to measure the physical properties of the gas. Densities, temperatures, clump masses, peak velocities, and line widths were measured and calculated using these observations. We have identified two condensations (S175A and S175B) in the molecular cloud associated with this H ii region. S175A is adjacent to the ionization front and is expected to be affected by the H ii 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 H ii region. S175A has been heated by the H ii region and partially compressed by the ionized gas front, but contrary to our expectation it is a quiescent region while S175B is very turbulent and dynamically active. Our investigation for the source of turbulence in S175B resulted in the detection of an outflow within this region.