Mizuno, Yoji and Kawamura, Akiko and Onishi, Toshikazu and Minamidani, Testuhiro and Muller, Erik and Yamamoto, Hiroaki and Hayakawa, Takahiro and Mizuno, Norikazu and Mizuno, Akira and Stutzki, Jürgen and Pineda, Jorge L. and Klein, Uli and Bertoldi, Frank and Koo, Bon-Chul and Rubio, Monica and Burton, Michael and Benz, Arnold and Ezawa, Hajime and Yamaguchi, Nobiyuki and Kohno, Kotaro and Hasegawa, Tetsuo and Tatematsu, Ken'ichi and Ikeda, Masafumi and Ott, Jürgen and Wong, Tony and Hughes, Annie and Meixner, Margaret and Indebetouw, Remy and Gordon, Karl D. and Whitney, Barbara and Bernard, Jean-Philippe and Fukui, Yasuo (2010) Warm and Dense Molecular Gas in the N 159 Region: ^(12)CO J = 4–3 and ^(13)CO J = 3–2 Observations with NANTEN2 and ASTE. Publications of the Astronomical Society of Japan, 62 (1). pp. 51-67. ISSN 0004-6264 http://resolver.caltech.edu/CaltechAUTHORS:20100616-152125075
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New ^(12)CO J = 4–3 and ^(13)CO J = 3–2 observations of the N 159 region, an active site of massive star formation in the Large Magellanic Cloud, have been made with the NANTEN2 and ASTE submillimeter telescopes, respectively. The ^(12)CO J = 4–3 distribution is separated into three clumps, each associated with N 159 W, N 159 E, and N 159 S. These new measurements toward the three clumps are used in coupled calculations of molecular rotational excitation and line radiation transfer, along with other transitions of the ^(12)CO J = 1–0, J = 2–1, J = 3–2, and J = 7–6 as well as the isotope transitions of ^(13)CO J = 1–0, J = 2–1, J = 3–2, and J = 4–3. The ^(13)CO J = 3–2 data were newly taken for the present work. The temperatures and densities were found to be ~70–80 K and ~3 × 10^3 cm^(-3) in N 159 W and N 159 E, and ~30 K and ~1.6 × 10^3 cm^(-3) in N 159 S. These results were compared with the star-formation activity based on data of young stellar clusters and HII regions as well as midinfrared emission obtained with the Spitzer MIPS. The N 159 E clump is associated with cluster(s) embedded, as observed at 24 μm by the Spitzer MIPS, and the derived high temperature, 80 K, is interpreted as being heated by these sources. The N 159 E clump is likely to be responsible for a dark lane in a large HII region by dust extinction. On the other hand, the N 159 W clump is associated with clusters embedded mainly toward the eastern edge of the clump only. These clusters show offsets of 20"–40" from the ^(12)CO J = 4–3 peak, and are probably responsible for heating indicated by the derived high temperature, 70 K. The N 159 W clump exhibits no sign of star formation toward the ^(12)CO J = 4–3 peak position and its western region that shows enhanced R_(4-3/1-0) and R_(3-2/1-0) ratios. We therefore suggest that the N 159 W peak represents a pre-star-cluster core of ~10^5 M_☉ which deserves further detailed studies. The N 159 S clump shows little sign of star formation, as is consistent with the lower temperature, 30 K, and has a somewhat lower density than N 159 W and N 159 E. The N 159 S clump is also a candidate for future star formation.
|Additional Information:||© 2010 Astronomical Society of Japan. Received 2009 January 5; accepted 2009 November 10. We thank all members of the NANTEN2 consortium and ASTE team for the operation and persistent efforts to improve the telescopes. This research was supported by a Grantin- Aid for Nagoya University Global COE Program, "Quest for Fundamental Principles in the Universe: From Particles to the Solar System and the Cosmos", from the Ministry of Education, Culture, Sports, Science and Technology of Japan (MEXT). This work is financially supported in part by a Grantin- Aid for Scientific Research from the MEXT (No. 15071203) and from Japan Society for the Promotion of Science (JSPS) (Nos. 14102003 and 18684003), and by the JSPS core-tocore program (No. 17004) and the Mitsubishi Foundation. This work is also financially supported in part by grant SFB 494 of Deutsche Forschungsgemeinschaft, Ministerium fur Innovation, Wissenschaft, Forschung und Technologie des Landes Nordrhein-Westfalen and through special grants of Universitiit zu Kaln and Universitiit Bonn. SAGE research has been funded by NASA/Spitzer grant 1275598 and NASA NAG5-12595. The ASTE project is driven by Nobeyama Radio Observatory (NRO), a branch of National Astronomical Observatory of Japan (NAOJ), in collaboration with University of Chile, and Japanese institutes including The University of Tokyo, Nagoya University, Osaka Prefecture University, Ibaraki University, and Hokkaido University. Observations with ASTE were in part carried out remotely from Japan by using NTT's GEMnet2 and its partner R&E (Research and Education) networks, which are based on AccessNova collaboration of University of Chile, NTT Laboratories, and NAOJ. A part of this study was financially supported by a Grant-inAid for Scientific Research on Priority Areas from the MEXT (No. 15071202).|
|Subject Keywords:||galaxies: Magellanic Clouds; ISM: clouds; ISM: molecules; stars: formation; submillimeter|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Jason Perez|
|Deposited On:||23 Jun 2010 15:18|
|Last Modified:||26 Dec 2012 12:09|
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