Yusuke Hattori

CLOUD–CLOUD COLLISION AS A TRIGGER OF THE HIGH-MASS STAR FORMATION: A MOLECULAR LINE STUDY IN RCW 120

RCW120 is a Galactic HII region having a beautiful ring shape bright in infrared. Our new CO J=1-0 and J=3-2 observations performed with the NANTEN2, Mopra, and ASTE telescopes have revealed that two molecular clouds with a velocity separation of 20km/s are both physically associated with RCW120. The cloud at -8km/s apparently traces the infrared ring, while the other cloud at -28km/s is distributed just outside the opening of the infrared ring, interacting with the HII region as supported by high kinetic temperature of the molecular gas and by the complementary distribution with the ionized gas. A spherically expanding shell driven by the HII region is usually discussed as the origin of the observed ring structure in RCW120. Our observations, however, indicate no evidence of the expanding motion in the velocity space, being inconsistent with the expanding shell model. We here postulate an alternative that, by applying the model introduced by Habe & Ohta (1992), the exciting O star in RCW120 was formed by a collision between the present two clouds at a colliding velocity ~30km/s. In the model, the observed infrared ring can be interpreted as the cavity created in the larger cloud by the collision, whose inner surface is illuminated by the strong UV radiation after the birth of the O star. We discuss that the present cloud-cloud collision scenario explains the observed signatures of RCW120, i.e., its ring morphology, coexistence of the two clouds and their large velocity separation, and absence of the expanding motion.

The TWO MOLECULAR CLOUDS IN RCW 38: EVIDENCE FOR THE FORMATION OF THE YOUNGEST SUPER STAR CLUSTER IN THE MILKY WAY TRIGGERED BY CLOUD–CLOUD COLLISION

We present distributions of two molecular clouds having velocities of 2 km s

Triggered O Star Formation in M20 via Cloud–Cloud Collision: Comparisons between High-resolution CO Observations and Simulations

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KINEMATIC STRUCTURE OF MOLECULAR GAS AROUND HIGH-MASS YSO, PAPILLON NEBULA, IN N159 EAST IN THE LARGE MAGELLANIC CLOUD: A NEW PERSPECTIVE WITH ALMA

and 14 km s

High-mass star formation possibly triggered by cloud–cloud collision in the H ii region RCW 34

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Molecular clouds in the NGC 6334 and NGC 6357 region: Evidence for a 100 pc-scale cloud–cloud collision triggering the Galactic mini-starbursts

toward RCW 38, the youngest super star cluster in the Milky Way, in the

FOREST Unbiased Galactic plane Imaging survey with the Nobeyama 45 m telescope (FUGIN): Molecular clouds toward W 33; possible evidence for a cloud–cloud collision triggering O star formation

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Molecular clouds toward three Spitzer bubbles S116, S117, and S118: Evidence for a cloud–cloud collision which formed the three H ii regions and a 10 pc scale molecular cavity

CO (

Formation of the young compact cluster GM 24 triggered by a cloud–cloud collision

J=

RCW 36 in the Vela Molecular Ridge: Evidence for high-mass star-cluster formation triggered by cloud–cloud collision

1--0 and 3--2) and