A COMPREHENSIVE SURVEY OF HYDROGEN CHLORIDE IN THE GALAXY

摘要: We report new observations of the fundamental J = 1–0 transition HCl (at 625.918 GHz) toward a sample 27 galactic star-forming regions, molecular clouds, and evolved stars, carried out using Caltech Submillimeter Observatory. Fourteen sources in sample are also observed corresponding H^(37)Cl J 624.978 GHz). have obtained clear detections all but four targets, often in emission. Absorptions against bright background continuum seen nine cases, usually involving a delicate balance between emission absorption features. From RADEX modeling, we derive gas densities column for with is found wide range of environments, gas ranging from 10^5 to 10^7 cm^(−3). The abundance relative H_2 the range (3–30) × 10^(−10). Comparing chlorine solar neighborhood, this corresponds to a depletion factor up ~400, assuming that accounts one-third total the gas phase. [^(35)Cl]/[^(37)Cl] isotopic ratio rather varied, unity ~5, mostly lower than terrestrial value 3.1. Such variation highly localized, could be generated by nucleosynthesis supernovae, which predicts ^(37)Cl deficiency most models. ratios W3IRS4 W3IRS5 likely confine the progenitors supernovae stars relatively large mass (≳25 M_⊙) high metallicity (Z ~ 0.02).