Large-scale Molecular Gas Distribution in the M17 Cloud Complex: Dense Gas Conditions of Massive Star Formation?
Year: 2020
Type: article
Abstract: The non-uniform distribution of gas and protostars in molecular clouds is caused by combinations of various physical processes that are difficult to separate. We explore this non-uniform distribution in the M17 molecular cloud complex that hosts massive star formation activity using the 12CO (J = 1–0) and 13CO (J = 1–0) emission lines obtained with the Nobeyama 45 m telescope. Differences in clump properties such as mass, size, and gravitational boundedness reflect the different evolutionary stages of the M17-H ii and M17-IRDC clouds. Clumps in the M17-H ii cloud are denser, more compact, and more gravitationally bound than those in M17-IRDC. While M17-H ii hosts a large fraction of very dense gas (27%) that has a column density larger than the threshold of ∼1 g cm−2 theoretically predicted for massive star formation, this very dense gas is deficient in M17-IRDC (0.46%). Our HCO+ (J = 1–0) and HCN (J = 1–0) observations with the Taeduk Radio Astronomy Observatory 14 m telescope trace all gas with a column density higher than 3 × 1022 cm−2, confirming the deficiency of high-density (≳105 cm−3) gas in M17-IRDC. Although M17-IRDC is massive enough to potentially form massive stars, its deficiency of very dense gas and gravitationally bound clumps can explain the current lack of massive star formation.
Source: The Astrophysical Journal
Authors: Quang Nguyen-Luong, Fumitaka Nakamura, Koji Sugitani, Tomomi Shimoikura, Kazuhito Dobashi, Shinichi W. Kinoshita, Kee-Tae Kim, Hynwoo Kang, Patricio Sanhueza, Neal J. Evans II, Glenn J. White
Institutions: Nagoya City University, McMaster University, The Graduate University for Advanced Studies, SOKENDAI, National Astronomical Observatory of Japan, The University of Tokyo, Otsuma Women's University, Tokyo Gakugei University, Korea Astronomy and Space Science Institute, Korea University of Science and Technology, The University of Texas at Austin, Rutherford Appleton Laboratory, The Open University
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
Awards: Understanding the Initial Structures of Cluster Forming Clumps, Revealing the origin of dark gas around molecular clouds using the velocity-dispersion method, ALMA-IMF: ALMA Transforms the View of the Origin of Stellar Masses, Development of science teaching program for university students at Faculty of Education, A Thorough Understanding of Role of Magnetic Field in Star Formation Process by CCS/SO Zeeman Observations
OpenAlex ID: W3009396936