Abstract
Aims. The Odin satellite has been used to search for the 118.75-GHz line of molecular oxygen (O-2) in the Galactic centre.
Methods. Odin observations were performed towards the Sgr A* circumnuclear disk (CND), and the Sgr A + 20 km s(-1) and + 50 km s(-1) 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 J = 13-12 HC3N line. Upper limits are presented for the 118.75-GHz O-2 (11-10) ground transition line and for the 118.11-GHz (3)Pi(2), J = 3-2 ground state SiC line at the Galactic centre. Upper limits are also presented for the 487-GHz O-2 line in the SgrA + 50 km s(-1) cloud and for the 157-GHz, J = 4-3, SiC line in the SgrA + 20 and + 50 km s(-1) clouds, as well as the CND. The CH3OH line complex at 157.2-157.3 GHz has been detected in the + 20 and + 50 km s(-1) clouds but not towards SgrA*/CND.
Conclusions. A 3 sigma upper limit for the fractional abundance ratio of [O-2]/[H-2] is found to be X(O-2) = 1.2 x 10(-7) towards the SgrA molecular belt region.
| Original language | English |
|---|---|
| Pages (from-to) | 849-853 |
| Number of pages | 5 |
| Journal | Astronomy & Astrophysics |
| Volume | 482 |
| Issue number | 3 |
| DOIs | |
| Publication status | Published - May 2008 |
Keywords
- galaxy : center
- ISM : individual objects : SgrA
- ISM : molecules
- ISM : clouds
- ISM : abundances
- RHO-OPHIUCHI CLOUD
- MOLECULAR CLOUDS
- SGR-A
- SATELLITE
- SUBMILLIMETER
- OXYGEN
- CYANOACETYLENE
- MILLIMETER
- CHEMISTRY
- EMISSION