| Autor: |
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 |
| Předmět: |
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| Zdroj: |
Astrophysical Journal; 3/1/2020, Vol. 891 Issue 1, p1-1, 1p |
| Abstrakt: |
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. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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