FOREST Unbiased Galactic plane Imaging survey with the Nobeyama 45-m telescope (FUGIN) : Molecular clouds toward W33 ; possible evidence for a cloud-cloud collision triggering O star formation

Abstract

We observed molecular clouds in the W33 high-mass star-forming region associated with compact and extended HII regions using the NANTEN2 telescope as well as the Nobeyama 45-m telescope in the $J=$1-0 transitions of ${}^{12}$CO, ${}^{13}$CO, and C${}^{18}$O as a part of the FOREST Unbiased Galactic plane Imaging survey with the Nobeyama 45-m telescope (FUGIN) legacy survey. We detected three velocity components at 35 km s${}^{-1}$, 45 km s${}^{-1}$, and 58 km s${}^{-1}$. The 35 km s${}^{-1}$ and 58 km s${}^{-1}$ clouds are likely to be physically associated with W33 because of the enhanced ${}^{12}$CO $J=$ 3-2 to $J=$1-0 intensity ratio as $R_{3-2/1-0}>1.0$ due to the ultraviolet irradiation by OB stars, and morphological correspondence between the distributions of molecular gas and the infrared and radio continuum emissions excited by high-mass stars. The two clouds show complementary distributions around W33. The velocity separation is too large to be gravitationally bound, and yet not explained by expanding motion by stellar feedback. Therefore, we discuss that a cloud-cloud collision scenario likely explains the high-mass star formation in W33.

arXiv comment29 pages, 18 figures, 3 tables, accepted for publication in PASJ

References in corpus (91)

• The CO-to-H2 Conversion Factor
• Grids of stellar models with rotation - I. Models from 0.8 to 120 Msun at solar metallicity (Z = 0.014)
• GLIMPSE: I. A SIRTF Legacy Project to Map the Inner Galaxy
• Toward Understanding Massive Star Formation
• Young massive star clusters
• The Formation of Massive Stars from Turbulent Cores
• ATLASGAL - The APEX Telescope Large Area Survey of the Galaxy at 870 microns
• Competitive accretion in embedded stellar cluster
• On the Formation of Massive Stars
• The Formation of Massive Star Systems by Accretion
• On the formation of massive stars
• Evolution of Massive Protostars with High Accretion Rates
• The WISE Catalog of Galactic HII Regions
• Radiation-Hydrodynamic Simulations of Collapse and Fragmentation in Massive Protostellar Cores
• Massive star formation: Nurture, not nature
• The Southern Galactic Plane Survey: HI Observations and Analysis
• A Parallax-based Distance Estimator for Spiral Arm Sources
• Star Formation in Disk Galaxies. I. Formation and Evolution of Giant Molecular Clouds via Gravitational Instability and Cloud Collisions
• ATLASGAL - Compact source catalogue: 330 < l < 21 degrees
• The COMPLETE Survey of Star-Forming Regions: Phase I Data
• Evolution of Massive Protostars via Disk Accretion
• Global Star Formation Rates in Disk Galaxies and Circumnuclear Starbursts from Cloud Collisions
• HARP/ACSIS: A submillimetre spectral imaging system on the James Clerk Maxwell Telescope
• Formation of Massive Molecular Cloud Cores by Cloud-cloud Collision
• The most massive stars in the Arches cluster
• FOREST Unbiased Galactic plane Imaging survey with the Nobeyama 45-m telescope (FUGIN) I: Project Overview and Initial Results
• 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
• Molecular Clouds Toward the Super Star Cluster NGC3603; Possible Evidence for a Cloud-Cloud Collision in Triggering the Cluster Formation
• A distance limited sample of massive molecular outflows
• Isolating signatures of major cloud-cloud collisions using position-velocity diagrams
• On-The-Fly Observing System of the Nobeyama 45-m and ASTE 10-m Telescopes
• The frequency and nature of `cloud-cloud collisions' in galaxies
• Cloud-cloud collision as a trigger of the high-mass star formation; a molecular line study in RCW120
• The two molecular clouds in RCW 38; evidence for formation of the youngest super star cluster in the Milky Way triggered by cloud-cloud collision
• From the Convergence of Filaments to Disk-Outflow Accretion: Massive-Star Formation in W33A
• Temperature and Density Distribution in the Molecular Gas Toward Westerlund 2: Further Evidence for Physical Association
• Molecular clouds in the Trifid nebula M20; Possible evidence for a cloud-cloud collision in triggering the formation of the first generation stars
• ATLASGAL --- Complete compact source catalogue: 280\degr\ $<\ell <$ 60\degr
• Triggered O star formation in M20 via cloud-cloud collision: Comparisons between high-resolution CO observations and simulations
• Isolating signatures of major cloud-cloud collisions II: The lifetimes of broad bridge features
• Formation of the Young Massive Cluster R136 triggered by Tidally-driven Colliding HI Flows
• The circumstellar disk, envelope, and bi-polar outflow of the Massive Young Stellar Object W33A
• Massive stars in massive clusters IV: Disruption of clouds by momentum-driven winds
• Finding Distant Galactic HII Regions
• Digital Spectro-Correlator System for the Atacama Compact Array of the Atacama Large Millimeter/submillimeter Array
• Star Formation triggered by cloud-cloud collisions
• Cluster Formation Triggered by Filament Collisions in Serpens South
• Evidence For Cloud-Cloud Collision and Parsec-Scale Stellar Feedback Within the L1641-N Region
• Trigonometric Parallaxes of Massive Star Forming Regions: G012.88+0.48 and W33
• Do Giant Molecular Clouds Care About the Galactic Structure?
• GMC Collisions as Triggers of Star Formation. III. Density and Magnetically Regulated Star Formation
• Formation of Massive, Dense Cores by Cloud-Cloud Collisions
• Was a cloud-cloud collision the trigger of the recent star formation in Serpens?
• GMC Collisions as Triggers of Star Formation. II. 3D Turbulent, Magnetized Simulations
• Cloud Structure of Galactic OB Cluster Forming Regions from Combining Ground and Space Based Bolometric Observations
• The origin of mid-infrared emission in massive young stellar objects: multi-baseline VLTI observations of W33A
• GMC Collisions as Triggers of Star Formation. V. Observational Signatures
• Kinematic Structure of Molecular Gas around High-mass Star YSO, Papillon Nebula, in N159 East in the Large Magellanic Cloud
• Environmental dependence of star formation induced by cloud collisions in a barred galaxy
• Evolutionary Description of Giant Molecular Cloud Mass Functions on Galactic Disks
• FOREST Unbiased Galactic plane Imaging survey with the Nobeyama 45-m telescope (FUGIN) 2: Possible evidence for formation of NGC~6618 cluster in M17 by cloud-cloud collision
• The ALMA view of W33A: A Spiral Filament Feeding the Candidate Disc in MM1-Main
• RCW 36 in the Vela Molecular Ridge: Evidence for a high-mass star cluster formation triggered by Cloud-Cloud Collision
• Diversity of chemistry and excitation conditions in the high-mass star forming complex W33
• GMC Collisions as Triggers of Star Formation. I. Parameter Space Exploration with 2D Simulations
• Molecular clouds in the NGC 6334 and NGC 6357 region; Evidence for a 100 pc-scale cloud-cloud collision triggering the Galactic mini-starbursts
• Colliding Filaments and a Massive Dense Core in the Cygnus OB 7 Molecular Cloud
• High-mass star formation possibly triggered by cloud-cloud collision in the HII region RCW 34
• L1188: a promising candidate of cloud-cloud collision triggering the formation of the low- and intermediate-mass stars
• Cloud-cloud Collision in the Galactic Center 50 km s${}^{-1}$ Molecular Cloud
• Formation of the young compact cluster GM 24 triggered by a cloud-cloud collision
• Molecular clouds toward three Spitzer bubbles S116, S117 and S118: Evidence for the cloud-cloud collision which formed the three \HII \ regions and a 10-pc scale molecular cavity
• ALMA view of G0.253+0.016: Can cloud-cloud collision form the cloud?
• Observational signatures of cloud-cloud collision in the extended star-forming region S235
• VLTI/MIDI 10 micron interferometry of the forming massive star W33A
• A Mapping Survey of Dense Clumps Associated with Embedded Clusters II : Can Clump-Clump Collisions Induce Stellar Clusters?
• Star Formation Induced by Cloud-Cloud Collisions and Galactic Giant Molecular Cloud Evolution
• A CO Line and Infrared Continuum Study of the Active Star-Forming Complex W51
• Star formation around mid-infrared bubble N37: Evidence of cloud-cloud collision
• The effect of photoionising feedback on star formation in isolated and colliding clouds
• Star Formation Activity in the molecular cloud G35.20$-$0.74: onset of cloud-cloud collision
• The formation of a Spitzer bubble RCW79 triggered by cloud-cloud collision
• Massive Stars in the W33 Giant Molecular Complex
• The Interstellar Medium and Star Formation of Galactic Disks. I. ISM and GMC properties with Diffuse FUV and Cosmic Ray Backgrounds
• A Multi-wavelength Study of the Massive Star-forming Region S87
• Molecular gas in the compact H{\sc ii} region RCW 166; possible evidence for an early phase of cloud-cloud collision prior to the bubble formation
• Dynamical cooling of galactic discs by molecular cloud collisions -- Origin of giant clumps in gas-rich galaxy discs
• SMA observations of C2H in High-Mass Star Forming Regions
• GMC Collisions As Triggers of Star Formation. IV. The Role of Ambipolar Diffusion
• OH and H2O maser variations in W33B

Cited by in corpus (33)

• Cloud-cloud collisions and triggered star formation
• Cloud-cloud collisions in the common foot point of molecular loops 1 and 2 in the Galactic Center
• FOREST Unbiased Galactic plane Imaging survey with the Nobeyama 45-m telescope (FUGIN) 2: Possible evidence for formation of NGC~6618 cluster in M17 by cloud-cloud collision
• Formation of the active star forming region LHA 120-N 44 triggered by tidally-driven colliding HI flows
• Molecular clouds in the NGC 6334 and NGC 6357 region; Evidence for a 100 pc-scale cloud-cloud collision triggering the Galactic mini-starbursts
• Synthetic observations of star formation and the interstellar medium
• Formation of the young compact cluster GM 24 triggered by a cloud-cloud collision
• Star Formation Induced by Cloud-Cloud Collisions and Galactic Giant Molecular Cloud Evolution
• FOREST Unbiased Galactic plane Imaging survey with the Nobeyama 45 m telescope (FUGIN). VI. Dense gas and mini-starbursts in the W43 giant molecular cloud complex
• ALMA CO Observations of a Giant Molecular Cloud in M33: Evidence for High-Mass Star Formation Triggered by Cloud-Cloud Collisions
• The formation of a Spitzer bubble RCW79 triggered by cloud-cloud collision
• Cloud-Cloud Collision Induced Star Formation in IRAS 18223-1243
• SiO emission as a probe of Cloud-Cloud Collisions in Infrared Dark Clouds
• Kinematics and star formation toward W33: a central hub as a hub--filament system
• Molecular gas in a Spitzer bubble N4: possible evidence for cloud-cloud collisions as a trigger of massive star formation
• Massive star formation in the Carina nebula complex and Gum 31 -- I. The Carina nebula complex
• ALMA-IMF X -- The core population in the evolved W33-Main (G012.80) protocluster
• FOREST Unbiased Galactic Plane Imaging Survey with the Nobeyama 45-m Telescope (FUGIN) IV: Galactic Shock Wave and Molecular Bow Shock in the 4-kpc Arm of the Galaxy
• A multiwavelength study of the W33 Main ultracompact HII region
• Unveiling molecular clouds toward bipolar HII region G8.14+0.23
• Formation of hub-filament structure triggered by cloud-cloud collision in W33 complex
• Distance determination of molecular clouds in the 1st quadrant of the Galactic plane using deep learning : I. Method and Results
• Uncovering distinct environments in an extended physical system around the W33 complex
• FOREST unbiased Galactic plane imaging survey with the Nobeyama 45 m telescope (FUGIN): Possible evidence of cloud-cloud collisions triggering high-mass star formation in the giant molecular cloud M16 (Eagle Nebula)
• Nobeyama 45 m Local Spur CO survey. I. Giant molecular filaments and cluster formation in the Vulpecula OB association
• Cloud structures in M17 SWex : Possible cloud-cloud collision
• A Multiwavelength Study of the Sgr B Region: Contiguous Cloud-Cloud Collisions Triggering Widespread Star Formation Events?
• Ionising feedback from an O star formed in a shock-compressed layer
• Ionized filaments and ongoing physical processes in massive star-forming sites around l = 345.5 degree
• Ammonia mapping observations of the Galactic infrared bubble N49: Three NH${}_3$ clumps along the molecular filament
• Massive star formation in the Carina nebula complex and Gum 31 -- II. a cloud-cloud collision in Gum 31
• KAgoshima Galactic Object survey with Nobeyama 45-metre telescope by Mapping in Ammonia lines (KAGONMA): Star formation feedback on dense molecular gas in the W33 complex
• FIRESTORM I: Stellar Feedback and Gas Kinematics in the Evolved W40 Hub-Filament System