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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents



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ID: 693672.0, MPI für Astronomie / Publikationen_mpia
High-fidelity view of the structure and fragmentation of the high-mass, filamentary IRDC G11.11-0.12
Authors:Kainulainen, J.; Ragan, S. E.; Henning, T.; Stutz, A.
Language:English
Date of Publication (YYYY-MM-DD):2013
Title of Journal:Astronomy and Astrophysics
Volume:557
Start Page:id.A120 (8 pp)
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:Star formation in molecular clouds is intimately linked to their internal mass distribution. We present an unprecedentedly detailed analysis of the column density structure of a high-mass, filamentary molecular cloud, namely IRDC G11.11-0.12 (G11). We use two novel column density mapping techniques: high-resolution (FWHM = 2″, or ~0.035 pc) dust extinction mapping in near- and mid-infrared, and dust emission mapping with the Herschel satellite. These two completely independent techniques yield a strikingly good agreement, highlighting their complementarity and robustness. We first analyze the dense gas mass fraction and linear mass density of G11. We show that G11 has a top heavy mass distribution and has a linear mass density (Ml ~ 600 M pc-1) that greatly exceeds the critical value of a self-gravitating, non-turbulent cylinder. These properties make G11 analogous to the Orion A cloud, despite its low star-forming activity. This suggests that the amount of dense gas in molecular clouds is more closely connected to environmental parameters or global processes than to the star-forming efficiency of the cloud. We then examine hierarchical fragmentation in G11 over a wide range of size-scales and densities. We show that at scales 0.5 pc ≳ l ≳ 8 pc, the fragmentation of G11 is in agreement with that of a self-gravitating cylinder. At scales smaller than l ≲ 0.5 pc, the results agree better with spherical Jeans' fragmentation. One possible explanation for the change in fragmentation characteristics is the size-scale-dependent collapse time-scale that results from the finite size of real molecular clouds: at scales l ≲ 0.5 pc, fragmentation becomes sufficiently rapid to be unaffected by global instabilities.
Free Keywords:ISM: clouds; ISM: structure; stars: formation; dust; extinction
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:ISSN:0004-6361 [ID No:1]
URL:http://cdsads.u-strasbg.fr/abs/2013A%26A...557A.12... [ID No:2]
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