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arXiv · 1701.04669

A new look at the molecular gas in M42 and M43; possible evidence for cloud-cloud collision which triggered formation of the OB stars in the Orion Nebula Cluster

Yasuo Fukui·Kazufumi Torii·Yusuke Hattori·Atsushi Nishimura·Akio Ohama·Yoshito Shimajiri·Kazuhiro Shima·Asao Habe·Hidetoshi Sano·Mikito Kohno·Hiroaki Yamamoto·Kengo Tachihara·Toshikazu Onishi
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Abstract

The Orion Nebula Cluster toward the HII region M42 is the most outstanding young cluster at the smallest distance 410pc among the rich high-mass stellar clusters. By newly analyzing the archival molecular data of the 12CO(J=1-0) emission at 21" resolution, we identified at least three pairs of complementary distributions between two velocity components at 8km/s and 13km/s. We present a hypothesis that the two clouds collided with each other and triggered formation of the high-mass stars, mainly toward two regions including the nearly ten O stars, theta1 Ori and theta2 Ori, in M42 and the B star, NU Ori, in M43. The timescale of the collision is estimated to be ~0.1Myr by a ratio of the cloud size and velocity corrected for projection, which is consistent with the age of the youngest cluster members less than 0.1Myr. The majority of the low-mass cluster members were formed prior to the collision in the last one Myr. We discuss implications of the present hypothesis and the scenario of high-mass star formation by comparing with the other eight cases of triggered O star formation via cloud-cloud collision.

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Yasuo Fukui, Kazufumi Torii, Yusuke Hattori, Atsushi Nishimura, Akio Ohama, Yoshito Shimajiri, Kazuhiro Shima, Asao Habe, Hidetoshi Sano, Mikito Kohno, Hiroaki Yamamoto, Kengo Tachihara, Toshikazu Onishi. 2018-05-15. A new look at the molecular gas in M42 and M43; possible evidence for cloud-cloud collision which triggered formation of the OB stars in the Orion Nebula Cluster. https://doi.org/10.3847/1538-4357%2Faac217

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