Fundamental Vibrational Transitions of HCl Detected in CRL 2136

Abstract

We would like to understand the chemistry of dense clouds and their hot cores more quantitatively by obtaining more complete knowledge of the chemical species present in them. We have obtained high-resolution infrared absorption spectroscopy at 3-4 um toward the bright infrared source CRL 2136. The fundamental vibration-rotation band of HCl has been detected within a dense cloud for the first time. The HCl is probably located in the warm compact circumstellar envelope or disk of CRL 2136. The fractional abundance of HCl is (4.9-8.7)e-8, indicating that approximately 20 % of the elemental chlorine is in gaseous HCl. The kinetic temperature of the absorbing gas is 250 K, half the value determined from infrared spectroscopy of 13CO and water. The percentage of chlorine in HCl is approximately that expected for gas at this temperature. The reason for the difference in temperatures between the various molecular species is unknown.

6 pages, 3 figures, A&A in press

References in corpus (3)

• Hydrogen chloride in diffuse interstellar clouds along the line of sight to W31C (G10.6-0.4)
• Direct Determination of the HF/H2 Abundance Ratio in Interstellar Gas
• Water Absorption from Gas Very Near the Massive Protostar AFGL 2136 IRS 1

Cited by in corpus (8)

• Interstellar Hydrides
• Detection of chloronium and measurement of the 35Cl/37Cl isotopic ratio at z=0.89 toward PKS1830-211
• Searches for HCl and HF in comets 103P/Hartley 2 and C/2009 P1 (Garradd) with the Herschel space observatory
• The H${}_2$O Spectrum of the Massive Protostar AFGL 2136 IRS 1 from 2 to 13 $\mu$m at High Resolution: Probing the Circumstellar Disk
• Chlorine Isotope Ratios in M Giants
• Anomalous intensities in the infrared emission of CH${}^{+}$ explained by quantum nuclear motion and electric dipole calculations
• Search for H${}_3^{+}$ isotopologues toward CRL 2136 IRS 1
• The high resolution infrared spectrum of HCl${}^{+}$