Molecular Clouds Associated with H ii Regions and Candidates within l = 106.°65 to 109.°50 and b = −1.°85 to 0.°95

• Published in: Research in astronomy and astrophysics 2022-04, Vol.22 (4), p.45008
• Main Authors: Li, Chun-Xue, Wang, Hong-Chi, Ma, Yue-Hui, Zhang, Miao-Miao, Li, Chong, Zheng, Yu-Qing
• Format: Article
• Language: English
• Subjects: (ISM:) HII regions; Clouds; Emission; Filaments; H II regions; ISM: clouds; ISM: molecules; ISM: structure; Molecular clouds; Molecular gases; Mountains; Parameters; Radial velocity; Solar neighborhood; Star & galaxy formation; Star formation
• ISSN: 1674-4527; 2397-6209
• DOI: 10.1088/1674-4527/ac52a0

We present a large-scale simultaneous survey of the CO isotopologues ( 12 CO, 13 CO, and C 18 O) J = 1–0 line emission toward the Galactic plane region of l = 106.°65 to 109.°50 and b = −1.°85 to 0.°95 using the Purple Mountain Observatory 13.7 m millimeter-wavelength telescope. Except for the molecular gas in the solar neighborhood, the emission from the molecular gas in this region is concentrated in the velocity range of [−60, −35] km s −1 . The gas in the region can be divided into four clouds, with mass in the range of ∼10 3 –10 4 M ☉ . We have identified 25 filaments based on the 13 CO data. The median excitation temperature, length, line mass, line width, and virial parameter of the filaments are 10.89 K, 8.49 pc, 146.11 M ⊙ pc −1 , 1.01 km s −1 , and 3.14, respectively. Among these filaments, eight have virial parameters of less than 2, suggesting that they are gravitationally bound and can lead to star formation. Nineteen H ii regions or candidates have previously been found in the region and we investigate the relationships between these H ii regions/candidates and surrounding molecular clouds in detail. Using morphology similarity and radial velocity consistency between H ii regions/candidates and molecular clouds as evidence for association, and raised temperature and velocity broadening as signatures of interaction, we propose that 12 H ii regions/candidates are associated with their surrounding molecular clouds. In the case of the H ii region of S142, the energy of the H ii region is sufficient to maintain the turbulence in the surrounding molecular gas.