SMA molecular line survey towards the massive star-forming region G10.6−0.4 in W31 complex

Abstract

Line surveys of complex molecules with millimeter and sub-millimeter telescopes are important for probing the physical and chemical environments of massive star forming regions (MSFRs). We present a molecular line survey with the Submillimeter Array (SMA) in the frequency ranges of 220.3–222.3 GHz and 230.3–232.3 GHz toward G10.6−0.4, the brightest star forming core in the W31 complex. Ninety-nine transitions from 22 molecular species and their isotopologues are identified. The moment 0 images of typical molecules show a compact core which is concentrated at the continuum peak position. Based on the local thermodynamic equilibrium assumption, the molecular line data are modeled. The rotational temperatures of those molecular species range from 96 to 178 K and their column densities range from 2.0 × 1014 to 3.7 × 1017 cm−2. The observational data suggest that all complex molecules are located in a warm environment. Chemical environments of the molecules are discussed. We compared molecular abundances and gas temperatures in G10.6−0.4 with those in other MSFRs, and found that gas temperatures and fractional abundances of specific molecules in G10.6−0.4 are similar to the typical MSFR W51 North, suggesting that there are similar physical and chemical environments in these two MSFRs.