First interstellar detection of OH+
Abstract
The Atacama Pathfinder Experiment (APEX) 12 m telescope was used to observe the N = 1-0, J = 0-1 ground-state transitions of OH+ at 909.1588 GHz with the CHAMP+ heterodyne array receiver. Two blended hyperfine structure transitions were detected in absorption against the strong continuum source Sagittarius B2(M) and in several pixels offset by 18´´. Both absorption from Galactic center gas and absorption from diffuse clouds in intervening spiral arms in a velocity range from -116 to 38.5 km s-1 is observed. The total OH+ column density of absorbing gas is 2.4 × 1015 cm-2. A column density local to Sgr B2(M) of 2.6 × 1014 cm-2 is found. On the intervening line-of-sight, the column density per unit velocity interval is in the range of 1 to 40 × 1012 cm-2/(km s-1). OH+ is found to be on average more abundant than other hydrides, such as SH+ and CH+. Abundance ratios of OH and atomic oxygen to OH+ are found in the range of 101-2 and 103-4, respectively. The detected absorption of a continuous velocity range on the line-of-sight shows OH+ to be an abundant component of diffuse clouds.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- July 2010
- DOI:
- 10.1051/0004-6361/201014364
- arXiv:
- arXiv:1004.2627
- Bibcode:
- 2010A&A...518A..26W
- Keywords:
-
- astrochemistry;
- ISM: abundances;
- ISM: molecules;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 5 pages, 4 figures. Accepted for publication in Astronomy and Astrophysics