Interaction between the Northern Coalsack in the Cygnus OB 7 cloud complex and multiple supernova remnants including HB 21

Abstract

We report possible interaction between multiple super nova remnants (SNRs) and Northern Coal Sack (NCS) which is a massive clump (∼ 1 × 10 3 M ⊙ ) in the Cyg OB 7 cloud complex and is forming a massive Class 0 object. We performed molecular observations of the 12 CO(J = 1 − 0), 13 CO(J = 1 − 0), and C 18 O(J = 1 − 0) emission lines using the 45m telescope at the Nobeyama Radio Observatory, and we found that there are mainly four velocity components at V LSR ≃ −20, −6, −4, and 10 km s −1 . The −6 and −4 km s −1 components correspond to the systemic velocities of NCS and the Cygnus OB 7 complex, respectively, and the other velocity components originate from distinct smaller clouds. Interestingly, there are apparent correlations and anti-correlations among the spatial distributions of the four components, suggesting that they are physically interacting with one another. On a larger scale, we find that a group of small clouds belonging to the −20 and 10 km s −1 components are located along two different arcs around some SNRs including HB 21 which has been suggested to be interacting with the Cyg OB 7 cloud complex, and we also find that NCS is located right at the interface of the arcs. The small clouds are likely to be the gas swept up by the stellar wind of the massive stars which created the SNRs. We suggest that the small clouds alined along the two arcs recently encountered NCS and the massive star formation in NCS was triggered by the strong interaction with the small clouds.

Cloud–cloud collision in the DR 21 cloud as a trigger of massive star formation

“…We suggest that the 12 CO emission with the intermediate velocities represents the gas drawn from the −3 and/or 9 km s −1 clouds. Similar feature has been found also in other star forming regions where cloud-cloud collisions are suggested (e.g., Dobashi et al 2019).…”

“…We further point out that in the northern part of the main filament between DR21(OH) and W75S-FIR3, there is another anticorrelation between the −3 and 9 km s −1 clouds in the 12 CO intensity distributions (figure 4a). Such anticorrelations can be regarded as an evidence of cloud-cloud collisions which often trigger massive star formation as seen in other star forming regions (e.g., Dobashi et al 2014;Matsumoto et al 2015;Dobashi et al 2019). We will further discuss this possibility in section 4.…”

Near-infrared imaging polarimetry toward M 17 SWex

“…One is perpendicular to the sheet-like structure, the other is parallel to it. The parallel configuration can be expected when the sheet-like structure was created by external large-scale flows such as an expansion of H II region (e.g., Shimoikura et al 2015Shimoikura et al , 2019, supernovae (e.g., Tatematsu et al 1990;Matsumoto et al 2015;Dobashi et al 2019a), or superbubbles (e.g., Inutsuka et al 2015). Since the M17 SWex cloud is close to the Galactic plane, such flows can be generally expected.…”

Cluster Formation in GGD12-15: Infall Motion with Rotation of the Natal Clump

“…Some other reports have identified candidates of infalling massive clumps by examining asymmetric profiles of optically thick molecular emission lines (e.g., Reiter et al 2011;He et al 2016). Cluster-formation can also be triggered by cloud-cloud or filament-filament collisions (e.g., Dobashi et al 2014Dobashi et al , 2019b, and can also be influenced by supernova remnants (e.g., Tatematsu et al 1990;Dobashi et al 2019a). Other than these, there can also be various gas motions in cluster forming regions such as powerful outflows as well as inflows caused by multiple protostars.…”