X-ray velocimetry of solar wind ion impact on comets

被引:78
作者
Beiersdorfer, P [1 ]
Lisse, CM
Olson, RE
Brown, GV
Chen, H
机构
[1] Univ Calif Lawrence Livermore Natl Lab, Dept Phys, Livermore, CA 94551 USA
[2] Space Telescope Sci Inst, Baltimore, MD 21218 USA
[3] Univ Missouri, Dept Phys, Rolla, MO 65401 USA
关键词
atomic data; atomic processes; comets : general; X-rays : general;
D O I
10.1086/319143
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
Laboratory measurements of the interaction of low-energy, bare, and hydrogen-like ions with neutral gases are presented. The measurements demonstrate that charge-exchange-induced cometary K-shell X-ray spectra represent rich spectral diagnostics for determining the speed of the solar wind and the collision dynamics within the coma. We show that the K-shell spectrum observed from low-energy ion-neutral collisions (less than or equal to 50 km s(-1)) has a distinct high-energy component that is suppressed in high-energy collisions (greater than or equal to 800 km s(-1)). As a result, the hardness ratio of the K-shell spectrum increases by as much as a factor of 4 as the ions decelerate in the coma. The change in spectral shape can be observed even with low-resolution energy dispersive solid-state detectors, opening the possibility of spatial imaging of the solar wind heavy-ion velocity profile in the coma. Our results clearly show that energy-dependent data are needed to fully describe charge-exchange-induced Xray production in the heliosphere.
引用
收藏
页码:L147 / L150
页数:4
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