2003A&A...398..621L


C.D.S. - SIMBAD4 rel 1.7 - 2019.11.17CET09:38:13

2003A&A...398..621L - Astronomy and Astrophysics, volume 398, 621-630 (2003/2-1)

Gas-phase recombination, grain neutralization and cosmic-ray ionization in diffuse gas.

LISZT H.

Abstract (from CDS):

Atomic ions are mostly neutralized by small grains (or PAH molecules) in current theories of heating and cooling in cool diffuse clouds; in the main they do not recombine with free electrons. This alters the ionization balance by depressing n(H+) and n(He+) while carbon generally remains nearly fully once-ionized: charge exchange with atomic oxygen and formation of H2 and OH also depress n(H+) in partly molecular gas. Seemingly restrictive empirical limits on ζH are relaxed and higher values for ζH are favored in a wide range of circumstances, when grain neutralization is recognized. Maintenance of the proton density at levels needed to reproduce observations of HD requires ζH>2x10–16/s, but such models naturally explain the presence of both HD and H3+ in relatively tenuous H I clouds. In dense gas, a higher ionization rate can account for high observed fractions of atomic hydrogen, and recognition of the effects of grain neutralization can resolve a major paradox in the formation of sulfur-bearing compounds.

Abstract Copyright:

Journal keyword(s): ISM: general - ISM: cosmic rays - ISM: atoms - ISM: molecules

Simbad objects: 7

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Number of rows : 7

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 * omi Per ** 03 44 19.13204 +32 17 17.6929 3.13 3.88 3.83 3.71 3.71 B1III 571 0
2 * zet Per V* 03 54 07.9224751 +31 53 01.081262 2.19 2.97 2.85 2.71 2.62 B1Ib 810 0
3 NAME Per B AGN 04 37 04.37510272 +29 40 13.8184969   21.7       ~ 458 2
4 * zet Oph Be* 16 37 09.5390545 -10 34 01.529471 1.73 2.58 2.56 2.46 2.50 O9.2IVnn 1708 2
5 HD 192639 s*b 20 14 30.4275040181 +37 21 13.815126140 6.83 7.46 7.11     O7.5Iabf 265 0
6 * 10 Lac ** 22 39 15.6786372 +39 03 00.971152 3.650 4.670 4.880 4.98 5.19 O9V 715 0
7 NAME Cas A SNR 23 23 24.000 +58 48 54.00           ~ 2338 1

    Equat.    Gal    SGal    Ecl

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2019.11.17-09:38:13

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