THE [C-II] 158-MICRON EMISSION FROM THE HORSEHEAD NEBULA

被引:24
作者
ZHOU, S
JAFFE, DT
HOWE, JE
GEIS, N
HERRMANN, F
MADDEN, SC
POGLITSCH, A
STACEY, GJ
机构
[1] MAX PLANCK INST EXTRATERR PHYS,W-8046 GARCHING,GERMANY
[2] UNIV ILLINOIS,DEPT ASTRON,URBANA,IL 61801
[3] UNIV CALIF BERKELEY,BERKELEY,CA 94720
[4] UNIV MARYLAND,DEPT ASTRON,COLL PK,MD 20742
[5] CORNELL UNIV,DEPT ASTRON,ITHACA,NY 14853
关键词
INFRARED; INTERSTELLAR; LINES; ISM; INDIVIDUAL (IC-434); MOLECULES;
D O I
10.1086/173473
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We have mapped the [C II] 158 mum line and observed several rotational lines of CO, (CO)-C-13 and CS toward selected positions in the Horsehead extinction region in IC 434. The observations show that the region has a gas density of about 10(4) cm-3 and an external UV flux 20-100 times the average interstellar UV field. Although this is a regime where the C+ emission varies rapidly with UV intensity, fine-structure line emission from gas with this range of physical conditions has not been investigated previously. Comparisons of our results with models of photodissociation regions show that existing plane-parallel photodissociation region models are in general agreement with the observed intensity. It is not necessary to invoke a clumpy structure in the boundary layer to explain the observations, but the overall geometry of the cloud is important in determining the distribution of C+ emission.
引用
收藏
页码:190 / 196
页数:7
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