THE EFFECT OF VARYING COSMIC-RAY IONIZATION RATES ON DARK CLOUD CHEMISTRY

被引:40
作者
FARQUHAR, PRA
MILLAR, TJ
HERBST, E
机构
[1] Department of Mathematics, UMIST, PO Box 88, Manchester
[2] Departments of Physics and Astronomy, Ohio State University, 174 W. 18th Avenue, Columbus, 43210, OH
基金
美国国家科学基金会;
关键词
MOLECULAR PROCESSES; ISM; CLOUDS; COSMIC RAYS; MOLECULES; GALAXIES; ABUNDANCES;
D O I
10.1093/mnras/269.3.641
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We investigate the effects of varying the cosmic ray ionization rate in chemical models of dense interstellar clouds. In the absence of such ionization, a scenario which may be applicable to dark cloud cores, we find that chemi-ionization is able to drive a limited ion-neutral chemistry. Models of clouds in starburst galaxies, which may have enhanced cosmic ray fluxes, are also investigated and enable an upper limit to be derived for the cosmic ray ionization rate in M82. The derived value, which is about 700 times the typical value for Galactic molecular clouds, is in good agreement with that necessary to explain the recent observations of C I in this galaxy.
引用
收藏
页码:641 / 648
页数:8
相关论文
共 31 条
[1]  
Bates D.R., ApJ, 306, (1986)
[2]  
Baulch D.L., Et al., J. Phys. Chem. Ref. Data, 21, (1992)
[3]  
Black J.H., Interstellar Processes, (1987)
[4]  
Burton M.G., Tielens A.G.G.M., Hollenbach D.J., ApJ, 365, (1990)
[5]  
Cesarsky C.J., Volk H.J., A&A, 70, (1978)
[6]  
Chi X., Wolfendale A.W., J. Phys. G, 19, (1993)
[7]  
Gredel R., Lepp S., Dalgarno A., Herbst E., ApJ, 347, (1989)
[8]  
Giisten R., Serabyn E., Kasemann C., Schinkel A., Schneider G., Schultz A., Young K., ApJ, 402, (1993)
[9]  
Herbst E., Lee H.-H., Howe D.A., Millar T.J., MNRAS, 268, (1994)
[10]  
Herd C.R., Adams N.G., Smith D., ApJ, 349, (1990)