Detection of anhydrous hydrochloric acid, HCl, in IRC+10216 with the Herschel SPIRE and PACS spectrometers

TL;DR

This paper reports the detection of anhydrous hydrochloric acid (HCl) in the circumstellar envelope of IRC+10216 using Herschel spectrometers, revealing its abundance and distribution in the star's inner regions.

Contribution

First detection of HCl in IRC+10216 with detailed spectroscopic analysis using Herschel data, providing insights into its abundance and spatial extent.

Findings

HCl detected from J=1-0 to J=7-6 transitions

HCl abundance relative to H2 is 5x10^-8

HCl extends to the photodissociation zone

Abstract

We report on the detection of anhydrous hydrochloric acid (hydrogen chlorine, HCl) in the carbon-rich star IRC+10216 using the spectroscopic facilities onboard the Herschel satellite. Lines from J=1-0 up to J=7-6 have been detected. From the observed intensities, we conclude that HCl is produced in the innermost layers of the circumstellar envelope with an abundance relative to H2 of 5x10^-8 and extends until the molecules reach its photodissociation zone. Upper limits to the column densities of AlH, MgH, CaH, CuH, KH, NaH, FeH, and other diatomic hydrides have also been obtained.