Triggered O star formation in M20 via cloud-cloud collision: Comparisons between high-resolution CO observations and simulations

Abstract

High-mass star formation is one of the top-priority issues in astrophysics. Recent observational studies are revealing that cloud-cloud collisions may play a role in high-mass star formation in several places in the Milky Way and the Large Magellanic Cloud. The Trifid Nebula M20 is a well known galactic HII region ionized by a single O7.5 star. In 2011, based on the CO observations with NANTEN2 we reported that the O star was formed by the collision between two molecular clouds ~0.3,Myr ago. Those observations identified two molecular clouds towards M20, traveling at a relative velocity of 7.5 km/s. This velocity separation implies that the clouds cannot be gravitationally bound to M20, but since the clouds show signs of heating by the stars there they must be spatially coincident with it. A collision is therefore highly possible. In this paper we present the new CO J=1-0 and J=3-2 observations of the colliding clouds in M20 performed with the Mopra and ASTE telescopes. The high resolution observations revealed the two molecular clouds have peculiar spatial and velocity structures, i.e., the spatially complementary distribution between the two clouds and the bridge feature which connects the two clouds in velocity space. Based on a new comparison with numerical models, we find that this complementary distribution is an expected outcome of cloud-cloud collisions, and that the bridge feature can be interpreted as the turbulent gas excited at the interface of the collision. Our results reinforce the cloud-cloud collision scenario in M20.

accepted for publication in ApJ

References in corpus (5)

• Do cloud-cloud collisions trigger high-mass star formation? I. Small cloud collisions
• Molecular clouds towards RCW 49 and Westerlund 2; Evidence for cluster formation triggered by cloud-cloud collision
• Isolating signatures of major cloud-cloud collisions using position-velocity diagrams
• Cloud-cloud collision as a trigger of the high-mass star formation; a molecular line study in RCW120
• Spectacular Spitzer images of the Trifid Nebula: Protostars in a young, massive-star-forming region

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• Star Formation Activity in the molecular cloud G35.20$-$0.74: onset of cloud-cloud collision
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• Uncovering distinct environments in an extended physical system around the W33 complex
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• Ultracompact HII regions with extended emission: The case of G43.89-0.78 and its molecular environment
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