1 Stockholm Observatory, Stockholm University, AlbaNova University Center, 106 91 Stockholm, Sweden
2 Department of Earth and Space Sciences, Chalmers University of Technology, Onsala Space Observatory, 439 92 Onsala, Sweden
3 Omnisys Instruments AB, Solna Strandväg 78, 171 54 Solna, Sweden
4 OHB Sweden, PO Box 1269, 164 29 Kista, Sweden
5 Onsala Space Observatory, Chalmers University of Technology, 439 92 Onsala, Sweden
Received: 25 October 2016
Accepted: 21 December 2016
Context. The Odin satellite is now into its sixteenth year of operation, much surpassing its design life of two years. One of the sources which Odin has observed in great detail is the Sgr A complex in the centre of the Milky Way.
Aims. To study the presence of NH3 in the Galactic centre and spiral arms.
Methods. Recently, Odin has made complementary observations of the 572 GHz NH3 line towards the Sgr A +50 km s-1 cloud and circumnuclear disk (CND).
Results. Significant NH3 emission has been observed in both the +50 km s-1 cloud and the CND. Clear NH3 absorption has also been detected in many of the spiral arm features along the line of sight from the Sun to the core of our Galaxy.
Conclusions. The very large velocity width (80 km s-1) of the NH3 emission associated with the shock region in the southwestern part of the CND may suggest a formation/desorption scenario similar to that of gas-phase H2O in shocks/outflows.
Key words: Galaxy: center / ISM: individual objects: Sgr A / ISM: molecules / ISM: clouds
Odin is a Swedish-led satellite project funded jointly by the Swedish National Space Board (SNSB), the Canadian Space Agency (CSA), the National Technology Agency of Finland (Tekes), the Centre National d’Études Spatiales (CNES), France, and the European Space Agency (ESA). The former Space division of the Swedish Space Corporation, today OHB Sweden, is the prime contractor, also responsible for Odin operations.
The reduced spectra are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (188.8.131.52) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/599/A135
© ESO, 2017