The abundance of HOC+ in diffuse clouds
Abstract
We used the Plateau de Bure Interferometer to search for λ3mm absorption lines of \hocp from local diffuse and translucent clouds occulting compact extragalactic mm-wave continuum sources. We detected \hocp in three directions with column densities only 70-120 times below that of the \hcop isomer, a factor 5-50 higher than typically found in dense dark gas but comparable to recent observations of dense photon-dominated regions. The observed amounts of \hocp N(\hocp)/N(\HH) = 3-6× 10-11 can be made in quiescent diffuse gas at thermal gas-kinetic rates if the \HH O/OH ratio is of order unity, in mild violation of extant observational limits.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- December 2004
- DOI:
- 10.1051/0004-6361:20041649
- arXiv:
- arXiv:astro-ph/0408509
- Bibcode:
- 2004A&A...428..117L
- Keywords:
-
- ISM: molecules;
- astrochemistry;
- Astrophysics
- E-Print:
- Accepted for publication in Astronomy and Astrophysics 23/08/2004