A Mapping Survey of Dense Clumps Associated With Embedded Clusters. Ii. Can Clump-Clump Collisions Induce Stellar Clusters?

Higuchi, Aya E.; Kurono, Yasutaka; Saito, Masao; Kawabe, Ryohei

doi:10.1088/0004-637x/719/2/1813

Cited by 27 publications

(34 citation statements)

References 52 publications

(69 reference statements)

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“…Such a collision of GMCs triggering active star formation (including cluster formation) has already been evidenced in the Sgr B2 region (Hasegawa et al 1994;Sato et al 2000) and more recently in the Trifid Nebula (Torii et al 2011), indicating that collisions of GMCs should play a key role in cluster formation. It is interesting to note that Higuchi et al (2009Higuchi et al ( , 2010 recently presented a study of 14 dense molecular clumps associated with embedded clusters including the same objects observed in our study (i.e., Clumps 1-3 in S247). They suggested that formation of clusters associated with Clumps 1-3 was triggered by clump-clump collisions based on the analyses of the velocity structures of the clumps.…”

Section: Global Distributions Of Young Stellar Objects and Molecular supporting

confidence: 65%

Molecular Clumps and Infrared Clusters in the S247, S252, and Bfs52 Regions

Shimoikura

Dobashi

Saito

et al. 2013

ApJ

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We present results of the observations carried out toward the S247, S252, and BFS52 H ii regions with various molecular lines using the 1.85 m radio telescope and the 45 m telescope at Nobeyama Radio Observatory. There are at least 11 young infrared clusters (IR clusters) within the observed region. We found that there are two velocity components in 12 CO (J = 2-1), and also that their spatial distributions show an anti-correlation. The IR clusters are located at their interfaces, suggesting that two distinct clouds with different velocities are colliding with each other, which may have induced the cluster formation. Based on 13 CO (J = 1-0) and C 18 O (J = 1-0) observations, we identified 16 clumps in and around the three H ii regions. Eleven of the clumps are associated with the IR clusters and the other five clumps are not associated with any known young stellar objects. We investigated variations in the velocity dispersions of the 16 clumps as a function of the distance from the center of the clusters or the clumps. Clumps with clusters tend to have velocity dispersions that increase with distance from the cluster center, while clumps without clusters show a flat velocity dispersion over the clump extents. A 12 CO outflow has been found in some of the clumps with IR clusters but not in the other clumps, supporting a strong relation of these clumps to the broader velocity dispersion region. We also estimated a mean star formation efficiency of ∼30% for the clumps with IR clusters in the three H ii regions.

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Section: Global Distributions Of Young Stellar Objects and Molecular supporting

confidence: 65%

Molecular Clumps and Infrared Clusters in the S247, S252, and Bfs52 Regions

Shimoikura

Dobashi

Saito

et al. 2013

ApJ

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“…This scenario is also suggested by recent studies of the global dynamics of Serpens and other star-forming regions (e.g. Higuchi et al 2010;Schneider et al 2010;Galván-Madrid et al 2010). …”

Section: Introductionsupporting

confidence: 66%

Was a cloud-cloud collision the trigger of the recent star formation in Serpens?

Duarte-Cabral

Dobbs

Peretto

et al. 2011

A&A

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Context. The complexity of the interstellar medium (ISM) is such that it is unlikely that star formation is initiated in the same way in all molecular clouds. While some clouds seem to collapse on their own, others may be triggered by an external event such as a cloud/flow collision forming a gravitationally unstable enhanced density layer. Aims. This work tests cloud-cloud collisions as the triggering mechanism for star formation in the Serpens Main Cluster as has been suggested by previous work. Methods. A set of smoothed particle hydrodynamics (SPH) simulations of the collision between two cylindrical clouds are performed and compared to (sub)millimetre observations of the Serpens Main Cluster. Results. A configuration was found that reproduces many of the observed characteristics of Serpens, including some of the main features of the peculiar velocity field. The evolution of the velocity with position throughout the model is similar to the observed one and the column density and masses within the modelled cloud agree with those measured for the SE sub-cluster. Furthermore, our results also show that an asymmetric collision provides the ingredients to reproduce lower density filaments perpendicular to the main structure, similar to those observed. In this scenario, the formation of the NW sub-cluster of Serpens can be reproduced only if there is a pre-existing marginally gravitationally unstable region at the time the collision occurs. Conclusions. This work supports the interpretation that a collision between two clouds may have been the trigger of the most recent burst of star formation in Serpens. It not only explains the complicated velocity structure seen in the region, but also the temperature differences between the north (in "isolated" collapse) and the south (resulting from the shock between the clouds). In addition it provides an explanation for the sources in the south having a larger spread in age than those in the north.

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“…There has been discussion that collisions between the interstellar molecular clouds may trigger the star formation (e.g., Loren 1976;Higuchi et al 2010;Duarte-Cabral et al 2011). Many of the previous studies reported discoveries of pairs of molecular clouds having velocity separations of a few km s −1 .…”

Section: Previous Studies On CCCmentioning

confidence: 99%

Cloud–cloud Collision as a Trigger of the High-Mass Star Formation: A Molecular Line Study in RCW 120

Torii

Hasegawa

Hattori

et al. 2015

ApJ

125

169

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RCW 120 is a Galactic H II region that has a beautiful ring shape that is bright in the 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 20 km s −1 are both physically associated with RCW 120. The cloud at −8 km s −1 apparently traces the infrared ring, while the other cloud at −28 km s −1 is distributed just outside the opening of the infrared ring, interacting with the H II region as suggested by the high kinetic temperature of the molecular gas and by the complementary distribution with the ionized gas. A spherically expanding shell driven by the H II region is usually considered to be the origin of the observed ring structure in RCW 120. Our observations, however, indicate no evidence of the expanding motion in the velocity space, which is inconsistent with the expanding shell model. We postulate an alternative that, by applying the model introduced by Habe & Ohta, the exciting O star in RCW 120 was formed by a collision between the present two clouds at a collision velocity of ∼30 km s −1 . 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 ultraviolet radiation after the birth of the O star. We discuss that the present cloud-cloud collision scenario explains the observed signatures of RCW 120, i.e., its ring morphology, coexistence of the two clouds and their large velocity separation, and absence of the expanding motion.

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A Mapping Survey of Dense Clumps Associated With Embedded Clusters. Ii. Can Clump-Clump Collisions Induce Stellar Clusters?

Cited by 27 publications

References 52 publications

Molecular Clumps and Infrared Clusters in the S247, S252, and Bfs52 Regions

Molecular Clumps and Infrared Clusters in the S247, S252, and Bfs52 Regions

Was a cloud-cloud collision the trigger of the recent star formation in Serpens?

Cloud–cloud Collision as a Trigger of the High-Mass Star Formation: A Molecular Line Study in RCW 120

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