2024/10/06 by David A. Neufeld, Curtis DeWitt, Neufeld, David A. +11
Physics and Astronomy · #Astrophysics and Star Formation Studies #Astrophysics of Galaxies (astro-ph.GA) #Atomic and Molecular Physics #FOS: Physical sciences #Stellar, planetary, and galactic studies
paper · pdf · doi:10.48550/arxiv.2410.04473
openalex publication_date 2024/10/06 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Using the EXES instrument on SOFIA, we have obtained velocity-resolved spectra of several pure rotational lines of H2 toward shocked molecular gas within three Galactic sources: the supernova remnant (SNR) IC443 (Clump C), a protostellar outflow in the intermediate-mass star-forming region NGC 2071, and the SNR 3C391. These observations had the goal of searching for expected velocity shifts between ortho- and para-H2 transitions emitted by C-type shocks. In contrast in our previous similar study of HH7, the result of our search was negative: no velocity shifts were reliably detected. Several possible explanations for the absence of such shifts are discussed: these include a preshock ortho-to-para ratio that is already close to the high-temperature equilibrium value of 3 (in the case of IC443C), the more complex shock structures evident in all these sources, and the larger projected aperture sizes relative to those in the observations of HH7.