Cluster formation triggered by filament collisions in Serpens South

Fumitaka Nakamura, Koji Sugitani, Tomohiro Tanaka, Hiroyuki Nishitani, Kazuhito Dobashi, Tomomi Shimoikura, Yoshito Shimajiri, Ryohei Kawabe, Yoshinori Yonekura, Izumi Mizuno, Kimihiko Kimura, Kazuki Tokuda, Minato Kozu, Nozomi Okada, Yutaka Hasegawa, Hideo Ogawa, Seiji Kameno, Hiroko Shinnaga, Munetake Momose, Taku NakajimaToshikazu Onishi, Hiroyuki Maezawa, Tomoya Hirota, Shuro Takano, Daisuke Iono, Nario Kuno, Satoshi Yamamoto

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63 Citations (Scopus)


The Serpens South infrared dark cloud consists of several filamentary ridges, some of which fragment into dense clumps. On the basis of CCS (J N = 43-32), HC3N (J = 5-4), N 2H+ (J = 1-0), and SiO (J = 2-1, v = 0) observations, we investigated the kinematics and chemical evolution of these filamentary ridges. We find that CCS is extremely abundant along the main filament in the protocluster clump. We emphasize that Serpens South is the first cluster-forming region where extremely strong CCS emission is detected. The CCS-to-N 2H+ abundance ratio is estimated to be about 0.5 toward the protocluster clump, whereas it is about 3 in the other parts of the main filament. We identify six dense ridges with different VLSR. These ridges appear to converge toward the protocluster clump, suggesting that the collisions of these ridges may have triggered cluster formation. The collisions presumably happened within a few × 105 yr because CCS is abundant only for a short time. The short lifetime agrees with the fact that the number fraction of Class I objects, whose typical lifetime is 0.4 × 105 yr, is extremely high, about 70% in the protocluster clump. In the northern part, two ridges appear to have partially collided, forming a V-shape clump. In addition, we detected strong bipolar SiO emission that is due to the molecular outflow blowing out of the protostellar clump, as well as extended weak SiO emission that may originate from the filament collisions.

Original languageEnglish
Article numberL23
JournalAstrophysical Journal Letters
Issue number2
Publication statusPublished - Aug 20 2014
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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