Norikazu Mizuno

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

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

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Chemical variation in molecular cloud cores in the Orion A cloud. II.

and 14 km s

A Detailed Study of the Interstellar Protons toward the TeV γ-Ray SNR RX J0852.0–4622 (G266.2–1.2, Vela Jr.): The Third Case of the γ-Ray and ISM Spatial Correspondence

^{-1}

An analysis of star formation with Herschel in the Hi-GAL Survey II. The tips of the Galactic bar

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

Detection of a turbulent gas component associated with a starless core with subthermal turbulence in the Orion A cloud

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Discovery of Molecular and Atomic Clouds Associated with the Magellanic Superbubble 30 Doradus C

CO (

THE 1.1 mm CONTINUUM SURVEY OF THE SMALL MAGELLANIC CLOUD: PHYSICAL PROPERTIES AND EVOLUTION OF THE DUST-SELECTED CLOUDS*

J=

Detailed distributions of the CO J = (2 − 1)/J = (1 − 0) intensity ratios toward a large area of the central molecular zone

1--0 and 3--2) and