Mon. Not. R. Astron. Soc., 450, 4043-4049 (2015/July-2)
Large-scale filaments associated with Milky Way spiral arms.
WANG K., TESTI L., GINSBURG A., WALMSLEY C.M., MOLINARI S. and SCHISANO E.
Abstract (from CDS):
The ubiquity of filamentary structure at various scales throughout the Galaxy has triggered a renewed interest in their formation, evolution, and role in star formation. The largest filaments can reach up to Galactic scale as part of the spiral arm structure. However, such large-scale filaments are hard to identify systematically due to limitations in identifying methodology (i.e. as extinction features). We present a new approach to directly search for the largest, coldest, and densest filaments in the Galaxy, making use of sensitive Herschel HI-GAL (Herschel Infrared Galactic Plane Survey) data complemented by spectral line cubes. We present a sample of the nine most prominent Herschel filaments, including six identified from a pilot search field plus three from outside the field. These filaments measure 37-99 pc long and 0.6-3.0 pc wide with masses (0.5-8.3)x104 M☉, and beam-averaged (28 arcsec, or 0.4-0.7 pc) peak H2 column densities of (1.7-9.3)x 1022/cm2. The bulk of the filaments are relatively cold (17-21 K), while some local clumps have a dust temperature up to 25-47 K. All the filaments are located within ≲ 60 pc from the Galactic mid-plane. Comparing the filaments to a recent spiral arm model incorporating the latest parallax measurements, we find that 7/9 of them reside within arms, but most are close to arm edges. These filaments are comparable in length to the Galactic scaleheight and therefore are not simply part of a grander turbulent cascade.
© 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society (2015)
catalogues - stars: formation - ISM: clouds - ISM: structure - Galaxy: structure
Table 1: [WTG2015] GNN N=9 among (Nos G11-G239).
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