The fragmentation and stability of hierarchical structure in Serpens South

Journal Article · Tue Dec 20 04:00:00 EST 2016 · Astrophysical Journal

DOI:https://doi.org/10.3847/1538-4357/833/2/204· OSTI ID:22869644

Friesen, R. K. ^[1]; Bourke, T. L. ^[2]; Francesco, J. Di ^[3]; Gutermuth, R. ^[4]

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1. Dunlap Institute for Astronomy and Astrophysics, University of Toronto, Toronto, Ontario, M5S 3H4 (Canada)
2. SKA Organisation, Jodrell Bank Observatory, Lower Withington, Macclesfield SK11 9DL (United Kingdom)
3. National Research Council Canada, Radio Astronomy Program, 5071 West Saanich Rd, Victoria, BC, V9E 2E7 (Canada)
4. Department of Astronomy, University of Massachusetts Amherst, Amherst, MA 01003 (United States)

Filamentary structures are ubiquitous in molecular clouds, and have been recently argued to play an important role in regulating the size and mass of embedded clumps through fragmentation and mass accretion. Here, we reveal the dynamical state and fragmentation of filamentary molecular gas associated with the Serpens South protocluster through analysis of wide (∼4 pc×4 pc) observations of NH{sub 3} (1, 1) and (2, 2) inversion transitions with the Green Bank Telescope. Detailed modeling of the NH{sub 3} lines reveals that the kinematics of the cluster and surrounding filaments are complex. We identify hierarchical structure using a dendrogram analysis of the NH{sub 3} emission. The distance between neighbor structures that are embedded within the same parent structure is generally greater than expected from a spherical Jeans analysis, and is in better agreement with cylindrical fragmentation models. The NH{sub 3} line width-size relation is flat, and average gas motions are sub- or trans-sonic over all physical scales observed. Subsonic regions extend far beyond the typical 0.1 pc scale previously identified in star-forming cores. As a result, we find a strong trend of decreasing virial parameter with increasing structure mass in Serpens South. Extremely low virial parameters on the largest scales probed by our data suggest that the previously observed, ordered magnetic field is insufficient to support the region against collapse, in agreement with large radial infall motions previously measured toward some of the filaments. A more complex magnetic field configuration in the dense gas, however, may be able to support the filaments.

• OSTI ID: 22869644
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 833; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
COMPUTERIZED SIMULATION
CYLINDRICAL CONFIGURATION
DISTANCE
EMISSION
FILAMENTS
FRAGMENTATION
GALAXIES
MAGNETIC FIELD CONFIGURATIONS
MAGNETIC FIELDS
MASS
SPHERICAL CONFIGURATION
STABILITY
STARS
TELESCOPES