CO rotational line emission from a dense knot in Cassiopeia A: Evidence for active post-reverse-shock chemistry
Artikel i vetenskaplig tidskrift, 2013
We report a Herschel detection of high-J rotational CO lines from a dense knot in the supernova remnant Cas A. Based on a combined analysis of these rotational lines and previously observed ro-vibrational CO lines, we find the gas to be warm (two components at ~400 and 2000 K) and dense (1e6−7 cm-3), with a CO column density of ~5e17 cm-2. This, along with the broad line widths (~400 km/s), suggests that the CO emission originates in the post-shock region of the reverse shock. As the passage of the reverse shock dissociates any existing molecules, the CO has most likely reformed in the past several years in the post-shock gas. The CO cooling time is similar to the CO formation time, therefore we discuss possible heating sources (UV photons from the shock front, X-rays, electron conduction) that may maintain the high column density of warm CO.
ISM: individual objects: Cassiopeia A
ISM: supernova remnants
submillimeter: ISM
Författare
Sofia Wallström
Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik
C. Biscaro
Universität Basel
F. Salgado
Universiteit Leiden
John H Black
Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik
I.M. Cherchneff
Universität Basel
Sebastien Muller
Chalmers, Rymd- och geovetenskap, Onsala rymdobservatorium
O. Berné
Université de Toulouse
Centre national de la recherche scientifique (CNRS)
J. Rho
National Aeronautics and Space Administration (NASA)
SETI Institute
Aggm Tielens
Universiteit Leiden
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 558 L2 L2Ämneskategorier (SSIF 2011)
Astronomi, astrofysik och kosmologi
Fundament
Grundläggande vetenskaper
Infrastruktur
Onsala rymdobservatorium
DOI
10.1051/0004-6361/201322576