title: Detection of H3+ in the diffuse interstellar medium toward Cygnus OB2 No. 12.
abstract: The molecular ion H3+ is considered the cornerstone of interstellar chemistry because it initiates the reactions responsible for the production of many larger molecules. Recently discovered in dense molecular clouds, H3+ has now been observed in the diffuse interstellar medium toward Cygnus OB2 No. 12. Analysis of H3+ chemistry suggests that the high H3+ column density (3.8 x 10(14) per square centimeter) is due not to a high H3+ concentration but to a long absorption path. This and other work demonstrate the ubiquity of H3+ and its potential as a probe of the physical and chemical conditions in the interstellar medium.
authors.affiliation: Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637, USA.
authors.forename: B J
authors.initials: BJ
authors.lastname: McCall
authors.forename: T R
authors.initials: TR
authors.lastname: Geballe
authors.forename: K H
authors.initials: KH
authors.lastname: Hinkle
authors.forename: T
authors.initials: T
authors.lastname: Oka
mesh_terms: D055580:Astronomical Phenomena; D001256:Astronomy; D002248:Carbon Monoxide; D002414:Cations, Monovalent; D019443:Cosmic Dust; D003359:Cosmic Radiation; D005118:Extraterrestrial Environment; D008433:Mathematics; D013696:Temperature; D014316:Tritium
chemical_list: D002414:Cations, Monovalent; D019443:Cosmic Dust; D014316:Tritium; D002248:Carbon Monoxide