Sublimation from icy jets as a probe of the interstellar volatile content of comets

被引:55
作者
Blake, GA [1 ]
Qi, C
Hogerheijde, MR
Gurwell, MA
Muhleman, DO
机构
[1] CALTECH 150 21, Div Geol & Planetary Sci, Pasadena, CA 91125 USA
[2] Univ Colorado, JILA, Boulder, CO 80309 USA
[3] Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA
[4] Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA
关键词
D O I
10.1038/18372
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
Comets are some of the most primitive bodies left over from the Solar System's early history. They may preserve both interstellar material and material from the proto-solar nebula, and so studies of their volatile components can provide dues about the evolution of gases and ices, as a collapsing molecular cloud transforms into a mature planetary system(1,2). Previous observations of emission from rotational transitions in molecules have averaged over large areas of the inner coma, and therefore include both molecules that sublimed from the nucleus and those that result from subsequent chemical processes in the coma. Here we present high-resolution observations of emission from the molecules HNC, DCN and HDO associated with comet Hale-Bopp, Our data reveal are-like structures-icy jets-offset from (but close to) the nucleus. The measured abundance ratios on 1-3" scales are substantially different from those on larger scales(3-5), and cannot be accounted for by models of chemical processes in the coma(2,6,7); they ape, however, similar to the values observed in the cores of dense interstellar clouds and young stellar objects. We therefore propose that sublimation from millimetre-sized icy grains ejected from the nucleus provides access to relatively unaltered volatiles. The D/H ratios inferred from our data suggest that, by mass, Hale-Bopp (and by inference the outer regions of the early solar nebula) consists of greater than or equal to 15-40% of largely unprocessed interstellar material.
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页码:213 / 216
页数:4
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