2001/04/20 by J. R. Rizzo, J. Martín‐Pintado, J. Martin-Pintado +1 · 3 citations
Chemistry · Physics and Astronomy · #Astrophysics and Star Formation Studies #Spectroscopy and Laser Applications #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/320695
Accepted by ApJ Letters. 4 pages, 1 PS figure. Uses aastex.cls
arxiv created 2001/04/20 · openalex publication_date 2001/06/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
We report the detection of the (1, 1) and (2, 2) metastable lines of ammonia (NH 3 ) in the molecular cloud associated with the Wolf-Rayet (W-R) nebula NGC 2359. Besides the CO and H 2 , this is the first molecule detected in the environs of a W-R star. Width (Δ V 1/2 = 3 km s -1 ) and radial velocity ( V LSR ~ 54 km s -1 ) indicate that the NH 3 lines arise from the molecular cloud that is interacting with the W-R star. The rotational temperature derived from the (1, 1) and (2, 2) line intensity ratios is about 30 K, significantly larger than the typical kinetic temperature of the ambient gas of ~10 K. The derived NH 3 abundance is ~10 -8 . Line width, abundance, and kinetic temperature can be explained if NH 3 is released from dust grain mantles to the gas phase by shocks produced by the expansion of the bubble created by the W-R stellar wind. We briefly discuss the implications of the detection of warm NH 3 associated with a W-R star in connection to the hot NH 3 emission detected in the Galactic center and in the nuclei of external galaxies.