Submillimeter and molecular views of three Galactic ring-like HII regions

Abstract

We use SCUBA 850 micron and CO observations to analyze the surroundings of three Galactic ring-like HII regions, KR 7, KR 81, and KR 120 (Sh 2-124, Sh 2-165 and Sh 2-187), with the aim of finding sites of triggered star formation. We find one prominent submillimeter (sub-mm) source for each region, located at the interface between the HII region and its neutral surroundings. Using Two Micron All Sky Survey photometry, we find that the prominent sub-mm source for KR 120 probably contains an embedded cluster of young stellar objects (YSOs), making it a likely site for triggered star formation. The KR 7 sub-mm source could possibly contain embedded YSOs, while the KR 81 sub-mm source likely does not. The mass column densities for these dominant sub-mm sources fall in the ~0.1-0.6 g cm^{-2} range. The mass of the cold, dense material (clumps) seen as the three dominant sub-mm sources fall around ~100 Solar masses. We use the SCUBA Legacy catalog to characterize the populations of sub-mm sources around the HII regions, and compare them to the sources found around a previously studied similar ring-like HII region (KR 140) and near a massive star-forming region (W3). Finally, we estimate the IR luminosities of the prominent newly detected sub-mm sources and find that they are correlated with the clump mass, consistent with a previously known luminosity-mass relationship which this study shows to be valid over four orders of magnitude in mass.

27 pages, 24 figures, 4 tables. Accepted for publication by The Astronomical Journal

References in corpus (7)

• The Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey
• MAMBO Mapping of Spitzer c2d Small Clouds and Cores
• The SCUBA Legacy Catalogue: Continuum Objects Detected by SCUBA
• The star-forming content of the W3 giant molecular cloud
• A Sample of Intermediate-Mass Star-Forming Regions: Making Stars at Mass Column Densities <1 g/cm^2
• Sequential and Spontaneous Star Formation Around the Mid-Infrared Halo HII Region KR 140
• A sharper view of the outer Galaxy at 1420 and 408 MHz from the Canadian Galactic Plane Survey - I. Revisiting the KR catalogue and new Gigahertz Peaked Spectrum Sources

Cited by in corpus (3)

• Massive Star Formation at the Periphery of the Evolved Giant HII Region W 39
• IRAS 01202+6133 : A Possible Case of Protostellar Collapse Triggered by a Small HII Region
• Fragmented atomic shell around S187 HII region and its interaction with molecular and ionized gas