Hydroxyl, water, ammonia, carbon monoxide and neutral carbon towards the Sgr A complex. Issue Volume 9:Issue S303(2013) (22nd May 2014)

• Record Type: Journal Article
• Authors: Karlsson, R.; Sandqvist, Aa.; Hjalmarson, Å.; Winnberg, A.; Fathi, K.; Frisk, U.; Olberg, M.
• Is Part Of: Proceedings of the International Astronomical Union. Volume 9:Issue S303(2013)
• Page Start: 97
• Page End: 99
• Publication Date: 2014-05-22
• Subjects: Sgr A, -- +50, -- +20 km s−1 clouds, -- CND, -- OH, -- H2O abundances, -- gas-phase chemistry; Astronomy -- Congresses; Astronomy -- Periodicals; 520
• DOI: 10.1017/S174392131400026X
• Languages: English
• ISSNs: 1743-9213

Abstract

Abstract: We observed Hydroxyl, water, ammonia, carbon monoxide and neutral carbon towards the +50 km s −1 cloud (M−0.02−0.07), the circumnuclear disk (CND) and the +20 km s −1 (M−0.13−0.08) cloud in the Sgr A complex with the VLA, Odin and SEST. Strong OH absorption, H2 O emission and absorption lines were seen at all three positions. Strong C 18 O emissions were seen towards the +50 and +20 km s −1 clouds. The CND is rich in H2 O and OH, and these abundances are considerably higher than in the surrounding clouds, indicating that shocks, star formation and clump collisions prevail in those objects. A comparison with the literature reveals that it is likely that PDR chemistry including grain surface reactions, and perhaps also the influences of shocks has led to the observed abundances of the observed molecular species studied here. In the redward high-velocity line wings of both the +50 and +20 km s −1 clouds and the CND, the very high H2 O abundances are suggested to be caused by the combined action of shock desorption from icy grain mantles and high-temperature, gas-phase shock chemistry. Only three of the molecules are briefly discussed here. For OH and H2 O three of the nine observed positions are shown, while a map of the C 18 O emission is provided. An extensive paper was recently published with Open Access (Karlsson et al. 2013, A&A 554, A141).