NH3 survey observation of massive star-forming regionW43

Hiroyuki Nishitani, Kazuo Sorai, Asao Habe, Keita Hosaka, Yoshimasa Watanabe, Yukie Ohishi, Kazuhito Motogi, Tetsuhiro Minamidani, Masayuki Y. Fujimoto

研究成果: Review article査読


We consider the properties of giant molecular cloud complexes in the star-forming regionW43 with a resolution of several pc scale, and discuss their relations to the evolutionary stages of massive star formation. We performed a NH3 (J, K) = (1, 1), (2, 2), and (3, 3) inversion-line survey with the Hokkaido University 11-m telescope. Among 51 observed positions, selected based on integrated intensity maps of 13CO (J = 1-0), these three emissions were detected from 21, 8, and 5 positions, respectively. The integrated intensity of the NH3 (J, K) = (1, 1) line was found to be proportional to the far-infrared luminosity, estimated from IRAS data. The rotation temperatures were deduced to be ∼15-20K at eight observed positions. In addition, the upper limits were estimated for 13 positions, which include the relatively low temperatures below 14K at two positions with a relatively high fractions of NH3 for 13CO and with a low far-infrared luminosity. We derived the ortho-to-para abundance ratio of NH 3. From the population distribution between the ortho- and para-levels of NH3, we also derived temperatures of ∼6-12K, which may be interpreted as the temperatures when NH3 molecules were formed. We discuss the relevance of the present results of our observations to the massive star-formation process and the current status of the W43 region while taking into account previous observations of other indicators of massive star formation. It is shown that the complexes contain several regions in different evolutionary stages, or with the distinct characteristics of star formation within a timescales shorter than the lifetime of massive stars.

ジャーナルPublications of the Astronomical Society of Japan
出版ステータスPublished - 2012 4月 25

ASJC Scopus subject areas

  • 天文学と天体物理学
  • 宇宙惑星科学


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