In Search of Infall Motion in Molecular Clumps. IV. Mapping of the Global Infall Sources

作者：Yang, Yang; Chen, Xi^*; Jiang, Zhibo; Chen, Zhiwei; Yu, Shuling; Li, Jun

来源：Astrophysical Journal, 2023, 955(2): 154.

DOI：10.3847/1538-4357/aced09

• STAR-FORMING REGIONS
• HIGH-MASS STARS
• INTERMEDIATE-MASS
• YOUNG STARS
• CATALOG
• SAMPLE
• COLLAPSE
• OUTFLOW
• PROTOCLUSTERS
• CANDIDATES

We have used the IRAM 30 m telescope to map some targets with HCO+ (1-0) and (HCO+)-C-13 (1-0) lines in order to search for evidence of gas infall in clumps. In this paper, we report the mapping results for 13 targets. All of these targets show HCO+ emissions, while (HCO+)-C-13 emissions are observed in 10 of them. The HCO+ integrated intensity maps of 10 targets show clear clumpy structures, and nine targets show clumpy structures in the (HCO+)-C-13 maps. Using the RADEX radiative transfer code, we estimate the column density of (HCO+)-C-13, and we determine the abundance ratio [(HCO+)-C-13]/[H-2] to be approximately 10(-12)-10(-10). Based on the asymmetry of the HCO+ line profiles, we identify 11 targets that show blue profiles, while six clumps have evidence of global infall. We use the RATRAN and two-layer models to fit the HCO+ line profiles of these infall sources, and analyze their spatial distribution of the infall velocity. The average infall velocities estimated by these two models are 0.24-1.85 km s(-1) and 0.28-1.45 km s(-1), respectively. The mass infall rate ranges from approximately 10(-5) to 10(-2)M(circle dot) yr(-1), which suggests that intermediate- or high-mass stars may be forming in the target regions.

• 单位
  广州大学; 中国科学院