A Panchromatic Study Of Galactic Intermediate Mass Star Forming Regions

Download or read book A Panchromatic Study of Galactic Intermediate-mass Star-forming Regions written by Michael J. Lundquist and published by . This book was released on 2015 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt: Current research into Galactic star formation has focused primarily on either massive star-forming regions or nearby low-mass regions. We present results from a multi-wavelength survey of Galactic intermediate-mass star-forming regions (IM SFRs). These regions were selected from mid-infrared colors that specify cool dust and large PAH contribution, suggesting that they produce stars up to, but not exceeding, 8 solar masses. Using mid-infrared WISE data we have classified 984 candidate IM SFRs as star-like objects, galaxies, filamentary structures, or blobs/shells. Of the 984 candidates, 616 are probable star-forming regions (62.6%), 128 are filamentary structures (13.0%), 39 are point-like objects of unknown nature (4.0%), and 201 are galaxies (20.4%). Focusing on blobs/shells, the sites of active star-forming regions, we study the stellar and molecular content. First, we perform a pilot study of four of these regions, IRAS 00259+5625, IRAS 00420+5530, IRAS 01080+5717, and IRAS 05380+2020, at Galactic latitudes I b I > 5° using optical spectroscopy from the Wyoming Infrared Observatory along with near-infrared photometry from the Two-Micron All Sky Survey to investigate their stellar content, confirming the intermediate-mass nature of these candidate IM SFRs. Next, we continue the survey with seven additional regions, IRAS 23448+6010, IRAS 22451+6154, IRAS 06464-1650, IRAS 01573+6730, IRAS 01467+5339, IRAS 04275+3519, and IRAS 06293-0931. Then, we conduct a sub-millimeter survey of a sample of 128 IM SFRs, using the Onsala 20-m telescope to observe 13 CO (1-0) toward 67 northern IM SFRs, the 12-m Atacama Pathfinder EXperiment telescope to observe 13CO (2-1) toward 22 southern IM SFRs, and incorporate an additional 39 sources from the Boston University Five College Radio Astronomy Observatory (BU-FCRAO) Galactic Ring Survey which observed 13 CO (1-0). We find that IM SFRs have mean a molecular column density of 7.89x10−12 cm−2 , a factor of 3.1 lower than that for a sample of high-mass regions, and have a mean 13 CO linewidth of 1.84 km/s, a factor of 1.5 lower than that for high-mass regions. Finally, we demonstrate a correlation between 13 CO linewidth and infrared luminosity as well as between molecular column density and infrared luminosity for the 13 CO sample of intermediate-mass and high-mass regions.