Hierarchical fragmentation and differential star formation in the Galactic ‘Snake’: infrared dark cloud G11.11−0.12
By Ke Wang, Qizhou Zhang, L. Testi, F. V. D. Tak, Yue-fang Wu, Huawei Zhang, T. Pillai, F. Wyrowski, S. Carey, S. Ragan and 1 more. 2014
170 citations recorded by the source corpus.
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.
Subfields: Astronomy and Astrophysics, Spectroscopy
View Paper: https://www.semanticscholar.org/paper/1429407c6986465fad9999ae220b540cf13f127d
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In Astronomy and Astrophysics
- E. Vázquez-Semadeni
- Manuel Zamora-Avil'es
- J. Ballesteros-Paredes
- A. Palau
- G. C. G'omez
- Ralf Klessen
- S. Glover
- P. Hennebelle
In Spectroscopy
Citations in the corpus
- Global hierarchical collapse in molecular clouds. Towards a comprehensive scenario (2019, background): “However, in other works, focusing on colder infrared-quiet clumps at even earlier evolutionary stages, it is found that the actual masses of the fragments are often significantly larger than the Jeans mass (e.g., Bontemps et al. 2010; Wang et al. 2014; Zhang et al. 2015; Csengeri et al. 2017).”