THE SECOND SURVEY OF THE MOLECULAR CLOUDS IN THE LARGE MAGELLANIC CLOUD BY NANTEN. II. STAR FORMATION

Journal Article · Tue Sep 01 04:00:00 EDT 2009 · Astrophysical Journal, Supplement Series

DOI:https://doi.org/10.1088/0067-0049/184/1/1; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21301625

Kawamura, Akiko; Mizuno, Yoji; Minamidani, Tetsuhiro; Mizuno, Norikazu; Onishi, Toshikazu; Fukui, Yasuo ^[1]; Fillipovic, Miroslav D ^[2]; Staveley-Smith, Lister ^[3]; Kim, Sungeun ^[4]; Mizuno, Akira ^[5]

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1. Department of Astrophysics, Nagoya University, Furocho, Chikusaku, Nagoya 464-8602 (Japan)
2. University of Western Sidney, Penrith South DC, NSW 1797 (Australia)
3. School of Physics, M013, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009 (Australia)
4. Astronomy and Space Science Department, Sejong University, 98 Kwangjin-gu, Kunja-dong, Seoul, 143-747 (Korea, Republic of)
5. Solar-Terrestrial Environment Laboratory, Nagoya University, Furocho, Chikusaku, Nagoya 464-8601 (Japan)

We studied star formation activities in the molecular clouds in the Large Magellanic Cloud. We have utilized the second catalog of 272 molecular clouds obtained by NANTEN to compare the cloud distribution with signatures of massive star formation including stellar clusters, and optical and radio H II regions. We find that the molecular clouds are classified into three types according to the activities of massive star formation: Type I shows no signature of massive star formation; Type II is associated with relatively small H II region(s); and Type III with both H II region(s) and young stellar cluster(s). The radio continuum sources were used to confirm that Type I giant molecular clouds (GMCs) do not host optically hidden H II regions. These signatures of massive star formation show a good spatial correlation with the molecular clouds in the sense that they are located within {approx}100 pc of the molecular clouds. Among possible ideas to explain the GMC types, we favor that the types indicate an evolutionary sequence; i.e., the youngest phase is Type I, followed by Type II, and the last phase is Type III, where the most active star formation takes place leading to cloud dispersal. The number of the three types of GMCs should be proportional to the timescale of each evolutionary stage if a steady state of massive star and cluster formation is a good approximation. By adopting the timescale of the youngest stellar clusters, 10 Myr, we roughly estimate the timescales of Types I, II, and III to be 6 Myr, 13 Myr, and 7 Myr, respectively, corresponding to a lifetime of 20-30 Myr for the GMCs with a mass above the completeness limit, 5 x 10{sup 4} M {sub sun}.

• OSTI ID: 21301625
• Journal Information: Astrophysical Journal, Supplement Series, Journal Name: Astrophysical Journal, Supplement Series Journal Issue: 1 Vol. 184; ISSN 0067-0049; ISSN APJSA2
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
99 GENERAL AND MISCELLANEOUS
APPROXIMATIONS
CATALOGS
MAGELLANIC CLOUDS
STAR CLUSTERS
STARS
STEADY-STATE CONDITIONS