Abundance and chemistry of interstellar HOCO+.
We derive HOCO+ column densities approximately 10(15) cm-2 toward the Galactic center and < or = 10(12) cm-2 for cold dark clouds from observations and an LVG model.  We mapped the HOCO+ 4(04)-3(03) line toward Sgr A.  The fractional abundance of HOCO+ in the Galactic center region is three orders of magnitude larger than predicted by quiescent ion-molecule chemistry and an order of magnitude larger than predicted by a MHD shock model.  If HOCO+ traces interstellar CO2, the implied high abundance ([CO2] approximately [CO]) in the Galactic center may result from UV photolysis of grain mantles.
Minh
Y C
YC
Department of Physics and Astronomy, University of Massachusetts, Amherst 01003, USA.
Brewer
M K
MK
Irvine
W M
WM
Friberg
P
P
Johansson
L E
LE
D055580:Astronomical Phenomena; D001256:Astronomy; D002245:Carbon Dioxide / Q000032:analysis* / Q000737:chemistry*; D005118:Extraterrestrial Environment; D008956:Models, Chemical; D011522:Protons; D016082:Solar System; D013696:Temperature
D011522:Protons; D002245:Carbon Dioxide