Comet Giacobini-Zinner: In Situ Observations of Energetic Heavy Ions
Comet Giacobini-Zinner: In Situ Observations of Energetic Heavy Ions
复制标题
贾科比尼-津纳彗星：高能重离子的原位观测
DOI：
10.1126/science.232.4748.366
复制
发表时间：
1986
期刊：
影响因子：
56.9
通讯作者：
M. Scholer
中科院分区：
文献类型：
--
作者：
F. Ipavich;A. Galvin;G. Gloeckler;D. Hovestadt;B. Klecker;M. Scholer
结论性的证据表明，在贾科比尼-辛纳彗星的1.5 × 106公里范围内存在高能（535，0000至150，000电子伏）、重（>-12原子质量单位）、单电荷的彗星离子。观测是用国际彗星探测器航天器上的马里兰州大学/马克斯-普朗克研究所超低能电荷分析仪进行的。确定这些离子质量的最直接的证据是通过分析其中一个固态探测器的能量信号获得的;它在三西格玛水平上很重要。最大通量记录在最接近彗核前201小时和最接近彗核后201小时。如果假设这些粒子主要是以18 - 6原子质量单位的质量单电离的，那么将在彗星半径50，000公里处观测到的粒子角分布转换到一个分布几乎是各向同性的静止坐标系中，需要一个与当地太阳风速度一致的转换速度。这些水基离子是各向同性的参考系的存在意味着它们在电离后经历了强烈的俯仰角散射。如果这些离子被局部电离然后被太阳风拾取，则静止坐标系中的粒子能量将扩展到比预期高得多的值，这意味着离子被加速或加热。导出的离子密度为每立方厘米10.1，与拾取离子的产生和运输的粗略模型一致。
Conclusive evidence is presented for the existence of energetic (∼535,0000 to 150,000 electron volts), heavy (>-12 atomic mass units), singly charged cometary ions within ∼1.5 x 106 kilometers of comet Giacobini-Zinner. The observations were made with the University of Maryland/Max-Planck-Institut ultralow-energy charge analyzer on, the International Cometary Explorer spacecraft. The most direct evidence for establishing the mass of these ions was obtained from an analysis of the energy signals in one of the solid-state detectors; it is significant at the three-sigma level. Maximum fluxes were recorded ∼1 hour before and ∼1 hour after closest approach to the cometary nucleus. Transformation of the particle angular distributions observed at ∼50,000 kilometers radial distance from the comet during the inbound pass into a rest frame in which the distributions are nearly isotropic requires a transformation velocity that is consistent with the local solar wind velocity if one assumes that these particles are primarily singly ionized with a mass of 18 � 6 atomic mass units. The existence of a frame of reference in which these water-group ions were isotropic implies that they underwent strong pitch angle scattering after their ionization. Particle energies in the rest frame extend to substantially higher values than would be expected if these ions were locally ionized and then picked up by the solar wind, implying that the ions were accelerated or heated. The derived ion density, ∼0.1 per cubic centimeter, is consistent with a crude model for the production and transport of pickup ions.