Ion Chemistry in Photon-dominated Regions: Examining the [HCO+]/[HOC+]/[CO+] Chemical Network

Details Ion Chemistry in Photon-dominated Regions: Examining the [HCO+]/[HOC+]/[CO+] Chemical Network Ion Chemistry in Photon-dominated Regions: Examining the [HCO+]/[HOC+]/[CO+] Chemical Network

Dec 2004

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2004apj...616..966s&link_type=abstract

The Astrophysical Journal, Volume 616, Issue 2, pp. 966-975.

Astronomy and Astrophysics

Astronomy

26

Astrochemistry, Ism: H Ii Regions, Ism: Abundances, Ism: Clouds, Ism: Molecules, Radio Lines: Ism

Scientific paper

HOC+ and CO+ have been detected toward two well-known photon-dominated regions (PDRs), S140 and NGC 2023, using the Arizona Radio Observatory 12 m telescope. The J=1-->0 transition of HOC+ at 89 GHz and the two spin components of the N=2-->1 line of CO+ near 236 GHz were observed, as well as the J=1-->0 transitions of H13CO+ and HC18O+. The J=3-->2 line of HOC+ at 268 GHz was also mapped across the Orion Bar. The [HCO+]/[HOC+] ratios determined in S140 and NGC 2023 were ~12,408 and 1913, respectively, values indicative of quiescent molecular gas rather than PDR sources, where the abundance of HOC+ is thought to be enhanced. However, the beam in both these measurements may contain material from the adjoining molecular cloud, favoring HCO+. Alternatively, the [HCO+]/[HOC+] ratio may vary with Av in PDR regions. The [CO+]/[HOC+] ratio in S140 and NGC 2023, at several positions in the Orion Bar, and in other PDRs, on the other hand, falls uniformly in the range ~1-10. In addition, the line profiles of CO+ and HOC+ in the Orion Bar look remarkably similar. The syntheses of HOC+ and CO+ appear to be correlated in PDRs, most likely through the common precursor, C+. The reaction of C+ and H2O is thought to preferentially create HOC+, as opposed to HCO+, and C++OH or O2 leads favorably to CO+.

Affiliated with

Also associated with

No associations

Rating

Ion Chemistry in Photon-dominated Regions: Examining the [HCO+]/[HOC+]/[CO+] Chemical Network does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Ion Chemistry in Photon-dominated Regions: Examining the [HCO+]/[HOC+]/[CO+] Chemical Network, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ion Chemistry in Photon-dominated Regions: Examining the [HCO+]/[HOC+]/[CO+] Chemical Network will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1471800