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

submillimeter: ISM

ISM: supernova remnants


Sofia Wallström

Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik

C. Biscaro

Universität Basel

F. Salgado

Leiden Observatory Research Institute

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

Universite de Toulouse

CNRS Centre National de la Recherche Scientifique

J. Rho

NASA Ames Research Center

SETI Institute

Aggm Tielens

Leiden Observatory Research Institute

Astronomy and Astrophysics

0004-6361 (ISSN) 1432-0746 (eISSN)

Vol. 558 L2


Astronomi, astrofysik och kosmologi


Grundläggande vetenskaper


Onsala rymdobservatorium