2010/10/14 by Farahjabeen Islam, Cesare Cecchi-Pestellini, Serena Viti +1
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Excited state #Hydrogen #Infrared #Interstellar cloud #Interstellar medium #Molecular cloud #Observable #Radiative transfer #Relaxation (psychology) #Scientific Research and Discoveries #astro-ph.GA
paper · pdf · doi:10.1088/0004-637x/725/1/1111
published as ApJ 725 (2010) 1111-1123 · 32 pages, 8 figures, 5 tables
arxiv created 2010/10/14 · openalex publication_date 2010/11/23 · arxiv updated 2015/05/20 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Many theoretical and laboratory studies predict H 2 to be formed in highly excited rovibrational states. The consequent relaxation of excited levels via a cascade of infrared transitions might be observable in emission from suitable interstellar regions. In this work, we model H 2 formation pumping in standard dense clouds, taking into account the H/H 2 transition zone, through an accurate description of chemistry and radiative transfer. The model includes recent laboratory data on H 2 formation, as well as the effects of the interstellar UV field, predicting the populations of gas-phase H 2 molecules and their IR emission spectra. Calculations suggest that some vibrationally excited states of H 2 might be detectable toward lines of sight where significant destruction of H 2 occurs, such as X-ray sources, and provides a possible explanation as to why observational attempts resulted in no detections reported to date.