巨大分子雲G34における雲同士の衝突の観測証拠を確認（Observational Evidence Reveals Cloud-Cloud Collision in Giant Molecular Cloud G34）

2026-02-09 中国科学院（CAS）

Red and white contours represent the integrated intensity of ¹²CO in the velocity intervals of 38–40 km s−1 and 58–63 km s−1, respectively. (Image by XAO)

＜関連情報＞

• https://english.cas.cn/newsroom/research_news/phys/202602/t20260210_1150276.shtml
• https://academic.oup.com/mnras/article/546/2/staf2285/8408447

分子複合体G34における衝突誘起流出と誘発星形成の可能性 Possible collision-induced outflows and triggered star formation in the molecular complex G34

Mingke Sun,Jarken Esimbek,Christian Henkel,Jianjun Zhou,Gang Wu,Yuxin He,Dalei Li,Xindi Tang,Toktarkhan Komesh,Dilda Berdikhan,…
Monthly Notices of the Royal Astronomical Society  Published:02 January 2026
DOI:https://doi.org/10.1093/mnras/staf2285

ABSTRACT

G34 is an active star-forming region with complex velocity components. Within the 38–63 km s^-1 velocity range, we identify a possible cloud–cloud collision at a distance of ～3 kpc. Using the ¹²CO(⁠ J= 1–0) line from the Purple Mountain Observatory 13.7-m millimeter telescope to trace the diffuse gas structures associated with the collision. The gas components at 38–50 and 53–63 km s^-1 exhibit a U-shaped complementary distribution and a bridge feature in the position–velocity diagram. At the collision interface, the velocity dispersion of ¹²CO is significantly enhanced, which may result from the impact of the collision. We analyse the spatial distributions of 6.7 GHz CH₃OH masers, APEX Telescope Large Area Survey of the Galaxy (ATLASGAL) clumps, H ii regions, young stellar objects, and O-type stars, finding that most are concentrated near the collision interface. This supports a strong coupling between cloud–cloud collisions and star formation. In addition, we detect H i self-absorption features and molecular outflows at the interface. Based on observations of 6 and 2 cm HCO lines from the Effelsberg 100 m and Tianma Radio Telescope 64 m telescopes, along with NH₃ lines from the Nanshan 26 m telescope, we derive an H₂ volume density of 10⁴– 10⁵cm^-3 in the compressed region. Finally, we compare the collision time-scales (⁠≳0.35 Myr), the dynamical age of the H ii region G34.26+0.15 (⁠≳0.33 Myr), and the outflow time-scale (⁠～7.5 Myr). The results suggest that gas at the base of the U-shaped structure was compressed during the collision and driven into the outflow. After millions of years of evolution, the gas density increased, potentially triggering star formation.