3 years ago

Detailed CO ($J$ = 1--0, 2--1 and 3--2) observations toward an H{\sc ii} region RCW~32 in the Vela Molecular Ridge.

Yutaka Hasegawa, Rei Enokiya, Yusuke Hattori, Hiroaki Yamamoto, Hidetoshi Sano, Kimihiro Kimura, Kengo Tachihara, Yasuo Fukui, Akio Ohama, Kazufumi Torii, Hideo Ogawa, Katsuhiro Hayashi

We made CO ($J$ = 1--0, 2--1, and 3--2) observations toward an H{\sc ii} region RCW~32 in the Vela Molecular Ridge. The CO gas distribution associated with the H{\sc ii} region was revealed for the first time at a high resolution of 22 arcsec. The results revealed three distinct velocity components which show correspondence with the optical dark lanes and/or H$\alpha$ distribution. Two of the components show complementary spatial distribution which suggests collisional interaction between them at a relative velocity of $\sim$4 km~s$^{-1}$. Based on these results, we present a hypothesis that cloud-cloud collision determined the cloud distribution and triggered formation of the exciting star ionizing RCW~32. The collision time scale is estimated from the cloud size and the velocity separation to be $\sim$2 Myrs and the collision terminated $\sim$1 Myr ago, which is consistent with an age of the exciting star and the associated cluster. By combing the previous works on the H{\sc ii} regions in the Vela Molecular Ridge, we argue that the majority, at least four, of the H{\sc ii} regions in the Ridge were formed by triggering of cloud-cloud collision.

Publisher URL: http://arxiv.org/abs/1711.00722

DOI: arXiv:1711.00722v2

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