Odin observations of the Galactic centre in the 118-GHz band: Upper limit to the O2 abundance

Aa Sandqvist, B. Larsson, Å Hjalmarson, P. Bergman, P. Bernath, U. Frisk, M. Olberg, L. Pagani, L. M. Ziurys

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


Aims. The Odin satellite has been used to search for the 118.75-GHz line of molecular oxygen (O) in the Galactic centre.Methods. Odin observations were performed towards the Sgr circumnuclear disk (CND), and the Sgr A +20 km s and +50 km s molecular clouds using the position-switching mode. Supplementary ground-based observations were carried out in the 2-mm band using the ARO Kitt Peak 12-m telescope to examine suspected SiC features.Results. A strong emission line was found at 118.27 GHz, attributable to the HCN line. Upper limits are presented for the 118.75-GHz O ground transition line and for the 118.11-GHz , ground state SiC line at the Galactic centre. Upper limits are also presented for the 487-GHz O line in the Sgr A +50 km s cloud and for the 157-GHz, , SiC line in the Sgr A +20 and +50 km s clouds, as well as the CND. The CHOH line complex at 157.2-157.3 GHz has been detected in the +20 and +50 kms clouds but not towards Sgr /CND.Conclusions. A upper limit for the fractional abundance ratio of [ O] /[ H] is found to be (O) towards the Sgr A molecular belt region.

Original languageEnglish (US)
Pages (from-to)849-853
Number of pages5
JournalAstronomy and astrophysics
Issue number3
StatePublished - May 2008


  • Galaxy: center
  • ISM: abundances
  • ISM: clouds
  • ISM: individual objects: Sgr A
  • ISM: molecules

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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