Detection of Interstellar SO +: A Diagnostic of Dissociative Shock Chemistry
Abstract
SO(+), predicted to form efficiently by dissociative shocks, has been detected in the shocked molecular clump IC 443G, by means of four transitions at 3 and 1.3 mm wavelength. Its large line width establishes its formation by shocks, and the physical conditions derived from statistical equilibrium calculations (T = 50-200 K, n is about a few times 100,000/cu cm) match those of the Turner et al. (1992) model of IC 443G in which dissociative shocks control the chemistry of several species. It is argued that neither nondissociative shocks nor ion-molecule chemistry can produce detectable quantities of SO(+) in warm interstellar clouds, so that SO(+) is an unambiguous indicator of dissociative shocks - a property unique to this molecular species.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- September 1992
- DOI:
- 10.1086/186528
- Bibcode:
- 1992ApJ...396L.107T
- Keywords:
-
- Dissociation;
- Interstellar Chemistry;
- Interstellar Matter;
- Molecular Ions;
- Sulfur Oxides;
- Free Radicals;
- Microwave Spectra;
- Molecular Clouds;
- Astrophysics;
- ISM: MOLECULES;
- MOLECULAR PROCESSES;
- SHOCK WAVES