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Hierarchical fragmentation and differential star formation in the Galactic ‘Snake’: infrared dark cloud G11.11−0.12

Wang, Ke and Zhang, Qizhou and Testi, Leonardo and van der Tak, Floris and Wu, Yuefang and Zhang, Huawei and Pillai, Thushara and Wyrowski, Friedrich and Carey, Sean and Ragan, Sarah E. and Henning, Thomas (2014) Hierarchical fragmentation and differential star formation in the Galactic ‘Snake’: infrared dark cloud G11.11−0.12. Monthly Notices of the Royal Astronomical Society, 439 (4). pp. 3275-3293. ISSN 0035-8711. https://resolver.caltech.edu/CaltechAUTHORS:20140602-093522305

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Abstract

We present Submillimeter Array (SMA) λ = 0.88 and 1.3 mm broad-band observations, and Very Large Array (VLA) observations in NH_3 (J, K) = (1,1) up to (5,5), H_2O and CH_3OH maser lines towards the two most massive molecular clumps in infrared dark cloud (IRDC) G11.11−0.12. Sensitive high-resolution images reveal hierarchical fragmentation in dense molecular gas from the ∼1 pc clump scale down to ∼0.01 pc condensation scale. At each scale, the mass of the fragments is orders of magnitude larger than the Jeans mass. This is common to all four IRDC clumps we studied, suggesting that turbulence plays an important role in the early stages of clustered star formation. Masers, shock heated NH_3 gas, and outflows indicate intense ongoing star formation in some cores while no such signatures are found in others. Furthermore, chemical differentiation may reflect the difference in evolutionary stages among these star formation seeds. We find NH_3 ortho/para ratios of 1.1 ± 0.4, 2.0 ± 0.4, and 3.0 ± 0.7 associated with three outflows, and the ratio tends to increase along the outflows downstream. Our combined SMA and VLA observations of several IRDC clumps present the most in-depth view so far of the early stages prior to the hot core phase, revealing snapshots of physical and chemical properties at various stages along an apparent evolutionary sequence.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://arxiv.org/abs/1401.4157arXivDiscussion Paper
http://dx.doi.org/10.1093/mnras/stu127DOIArticle
http://mnras.oxfordjournals.org/content/439/4/3275.abstractPublisherArticle
ORCID:
AuthorORCID
Carey, Sean0000-0002-0221-6871
Additional Information:© 2014 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. First published online: February 25, 2014. Accepted 2014 January 16. Received 2014 January 15; in original form 2013 October 31. We thank the referee Michael Burton for valuable comments that helped clarify the manuscript. KW acknowledges support from the ESO fellowship, the European Union Lotus post-doctoral fellowship under the frame of Erasmus Mundus Action during his stay at Kapteyn, and the SMA pre-doctoral fellowship and China Scholarship Council during his stay at Harvard CfA. YW and KW thank the support by China Ministry of Science and Technology under State Key Development Program for Basic Research (2012CB821800). QZ acknowledge the partially support by the NSFC grant 11328301. SER is supported by grant RA 2158/1-1, which is part of the Deutsche Forschungsgemeinschaft priority program 1573 (‘Physics of the Interstellar Medium’). This research made use of open-source PYTHON packages APLPY and PYSPECKIT (Ginsburg & Mirocha 2011; Robitaille & Bressert 2012).
Funders:
Funding AgencyGrant Number
European Southern Observatory (ESO)UNSPECIFIED
Erasmus Mundus Action European Union Lotus postdoctoral fellowshipUNSPECIFIED
SMA pre-doctoral fellowshipUNSPECIFIED
China Scholarship CouncilUNSPECIFIED
Ministry of Science and Technology (Taipei)2012CB821800
NSFC11328301
Deutsche Forschungsgemeinschaft (DFG)RA 2158/1-1
Subject Keywords:accretion, accretion discs masers stars: early-type stars: formation ISM: individual objects: G11.11–0.12 ISM: jets and outflows
Issue or Number:4
Record Number:CaltechAUTHORS:20140602-093522305
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20140602-093522305
Official Citation:Ke Wang, Qizhou Zhang, Leonardo Testi, Floris van der Tak, Yuefang Wu, Huawei Zhang, Thushara Pillai, Friedrich Wyrowski, Sean Carey, Sarah E. Ragan, and Thomas Henning Hierarchical fragmentation and differential star formation in the Galactic ‘Snake’: infrared dark cloud G11.11−0.12 MNRAS (April 21, 2014) Vol. 439 3275-3293 first published online February 25, 2014 doi:10.1093/mnras/stu127
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:46026
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:02 Jun 2014 21:06
Last Modified:03 Oct 2019 06:39

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