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

Fukui, Y.; Kohno, Mikito; Yokoyama, Keiko; Torii, Kazufumi; Hattori, Yusuke; Sano, Hidetoshi; Nishimura, Atsushi; Ohama, Akio; Yamamoto, Hiroaki; Tachihara, Kengo

doi:10.1093/pasj/psy017

Cited by 41 publications

(19 citation statements)

References 63 publications

(54 reference statements)

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“…We also include in our analysis the CO (1-0) data from Fukui et al (2018) to study the global-scale velocity fields. The data were obtained with NANTEN2, which is a 4 m millimeter/sub-millimeter radio telescope in Chile.…”

Section: Nanten2 Co (1-0) Datamentioning

confidence: 99%

“…For the NANTEN2 CO (1-0) and JCMT 13 CO (3-2) observations, we only consider the line emission from -12 to 4 km s −1 since most of the large-scale line emission in the NGC 6334 region is within this velocity range (Arzoumanian et al 2022). A second and fainter velocity component in the NGC 6334 region from -20 to -12 km s −1 has been previously reported (Fukui et al 2018), but is not considered in this work. For the ALMA OCS and 13 CS lines, we consider slightly different velocity ranges for each clump as indicated in Figures 4 and 5.…”

Section: Molecular Lines and Velocity Fieldsmentioning

confidence: 99%

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Multi-scale physical properties of NGC 6334 as revealed by local relative orientations between magnetic fields, density gradients, velocity gradients, and gravity

Liu¹,

Zhang²,

Koch³

et al. 2022

Preprint

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We present ALMA dust polarization and molecular line observations toward 4 clumps (I(N), I, IV, and V) in the massive star-forming region NGC 6334. In conjunction with large-scale dust polarization and molecular line data from JCMT, Planck, and NANTEN2, we make a synergistic analysis of relative orientations between magnetic fields (θ B ), column density gradients (θ NG ), local gravity (θ LG ), and velocity gradients (θ VG ) to investigate the multi-scale (from ∼30 pc to 0.003 pc) physical properties in NGC 6334. We find that the relative orientation between θ B and θ NG changes from statistically more perpendicular to parallel as column density (N H2 ) increases, which is a signature of trans-tosub-Alfvénic turbulence at complex/cloud scales as revealed by previous numerical studies. Because θ NG and θ LG are preferentially aligned within the NGC 6334 cloud, we suggest that the more parallel alignment between θ B and θ NG at higher N H2 is because the magnetic field line is dragged by gravity. At even higher N H2 , the angle between θ B and θ NG or θ LG transits back to having no preferred orientation or statistically slightly more perpendicular, suggesting that the magnetic field structure is impacted by star formation activities. A statistically more perpendicular alignment is found between θ B and θ VG throughout our studied N H2 range, which indicates a trans-to-sub-Alfvénic state at small scales as well and signifies an important role of magnetic field in the star formation process in NGC 6334. The normalised mass-to-flux ratio derived from the polarization-intensity gradient (KTH) method increases with N H2 , but the KTH method may fail at high N H2 due to the impact of star formation feedback.

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Section: Nanten2 Co (1-0) Datamentioning

confidence: 99%

Section: Molecular Lines and Velocity Fieldsmentioning

confidence: 99%

Multi-scale physical properties of NGC 6334 as revealed by local relative orientations between magnetic fields, density gradients, velocity gradients, and gravity

Liu¹,

Zhang²,

Koch³

et al. 2022

Preprint

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“…In a collision site, a spatial and velocity connection of two cloud components is considered as a reliable characteristic of CCC (e.g., Torii et al 2011;Fukui et al 2014Fukui et al , 2015Torii et al 2015;Dewangan 2017;Nishimura et al 2017;Sano et al 2017;Torii et al 2017;Fukui et al 2018aFukui et al , 2018bHayashi et al 2018;Sano et al 2018;Fujita et al 2021;Fukui et al 2021;Torii et al 2021). Furthermore, two colliding clouds show a complementary distribution in position−position space (e.g., Dewangan et al 2018;Fukui et al 2018b;Fujita et al 2021) and a bridge feature (a low intensity flattened profile between two velocity peaks) in velocity space (e.g., Haworth et al 2015a;Dewangan & Ojha 2017;Torii et al 2017;Priestley & Whitworth 2021).…”

Section: W31-s: a Site Of CCCmentioning

confidence: 99%

Unraveling the Observational Signatures of Cloud–Cloud Collision and Hub-filament Systems in W31

Maity

Dewangan

Sano

et al. 2022

ApJ

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To understand the formation process of massive stars, we present a multiscale and multiwavelength study of the W31 complex hosting two extended H ii regions (i.e., G10.30-0.15 (hereafter, W31-N) and G10.15-0.34 (hereafter, W31-S)) powered by a cluster of O-type stars. Several Class i protostars and a total of 49 ATLASGAL 870 μm dust clumps (at d = 3.55 kpc) are found toward the H ii regions where some of the clumps are associated with the molecular outflow activity. These results confirm the existence of a single physical system hosting the early phases of star formation. The Herschel 250 μm continuum map shows the presence of a hub-filament system (HFS) toward both W31-N and W31-S. The central hubs harbor H ii regions and they are depicted with extended structures (with T d ∼ 25–32 K) in the Herschel temperature map. In the direction of W31-S, an analysis of the NANTEN2 12CO(J = 1−0) and SEDIGISM 13CO(J = 2−1) line data supports the presence of two cloud components around 8 and 16 km s−1, and their connection in velocity space. A spatial complementary distribution between the two cloud components is also investigated toward W31-S, where the signposts of star formation, including massive O-type stars, are concentrated. These findings favor the applicability of cloud–cloud collision (CCC) around ∼2 Myr ago in W31-S. Overall, our observational findings support the theoretical scenario of CCC in W31, which explains the formation of massive stars and the existence of HFSs.

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“…Several observations towards young high-mass star-forming regions that are proposed to be at early stage of cloud-cloud collisions also showed less or non-existent complementary gas distribution between the colliding clouds (e.g. Fukui et al 2016Fukui et al , 2018aHayashi et al 2020) Another observational support of cloud-cloud collision is the presence of the bridge feature. It represents the shocked interface layer in-between the two clouds and it manifests itself as a velocity component connecting the two clouds at the intermediate velocity in a position-velocity diagram.…”

Section: Scenario Of An Early Cloud-cloud Collision?mentioning

confidence: 99%

Cloud-cloud collision as drivers of the chemical complexity in Galactic Centre molecular clouds

Zeng,

Zhang,

Jimenez-Serra

et al. 2020

Preprint

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G+0.693-0.03 is a quiescent molecular cloud located within the Sagittarius B2 (Sgr B2) star-forming complex. Recent spectral surveys have shown that it represents one of the most prolific repositories of complex organic species in the Galaxy. The origin of such chemical complexity, along with the small-scale physical structure and properties of G+0.693-0.03, remains a mystery. In this paper, we report the study of multiple molecules with interferometric observations in combination with single-dish data in G+0.693-0.03. Despite the lack of detection of continuum source, we find small-scale (0.2 pc) structures within this cloud. The analysis of the molecular emission of typical shock tracers such as SiO, HNCO, and CH 3 OH unveiled two molecular components, peaking at velocities of 57 and 75 km s −1 . They are found to be interconnected in both space and velocity. The position-velocity diagrams show features that match with the observational signatures of a cloud-cloud collision. Additionally, we detect three series of class I methanol masers known to appear in shocked gas, supporting the cloud-cloud collision scenario. From the maser emission we provide constraints on the gas kinetic temperatures (∼30-150 K) and H 2 densities (10 4 -10 5 cm −2 ). These properties are similar to those found for the starburst galaxy NGC253 also using class I methanol masers, suggested to be associated with a cloud-cloud collision. We conclude that shocks driven by the possible cloud-cloud collision is likely the most important mechanism responsible for the high level of chemical complexity observed in G+0.693-0.03.

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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

Cited by 41 publications

References 63 publications

Multi-scale physical properties of NGC 6334 as revealed by local relative orientations between magnetic fields, density gradients, velocity gradients, and gravity

Multi-scale physical properties of NGC 6334 as revealed by local relative orientations between magnetic fields, density gradients, velocity gradients, and gravity

Unraveling the Observational Signatures of Cloud–Cloud Collision and Hub-filament Systems in W31

Cloud-cloud collision as drivers of the chemical complexity in Galactic Centre molecular clouds

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