期刊
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
卷 450, 期 4, 页码 4043-4049出版社
OXFORD UNIV PRESS
DOI: 10.1093/mnras/stv735
关键词
catalogues; stars: formation; ISM: clouds; ISM: structure; Galaxy: structure
资金
- ESO
- DFG [WA3628-1/1, 1573]
- National Science Foundation [AST-9800334, AST-0098562, AST-0100793]
- ESO programme [092.C-0713]
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) x 10(4) M-circle dot, and beam-averaged (28 arcsec, or 0.4-0.7 pc) peak H-2 column densities of (1.7-9.3) x 10(22) cm(-2). 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 less than or similar to 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.
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