Pitch Angle Distributions of Energetic Particles Near Callisto

Author:

Krupp N.1ORCID,Roussos E.1ORCID,Fränz M.1,Kollmann P.2ORCID,Paranicas C.2ORCID,Clark G.2ORCID,Khurana K.3ORCID,Galli A.4ORCID

Affiliation:

1. Max Planck Institute for Solar System Research Göttingen Germany

2. The Johns Hopkins University Applied Physics Laboratory Laurel MD USA

3. University of California Los Angeles Los Angeles CA USA

4. Physikalisches Institut University of Bern Bern Switzerland

Abstract

AbstractThe Galileo spacecraft performed close flybys of the moon Callisto between 1996 and 2001. We reanalyzed particle data of the energetic particles detector onboard Galileo and derived pitch angle distributions in the energy range of several keV to MeV during Callisto flybys C3, C9, C10, and C30. We establish that field‐aligned beams observed during the flyby periods are more likely to originate from Callisto's magnetospheric interaction rather than by independent magnetospheric processes. These beams are prominent only during flyby C3, they come mainly from the North, and connect the moon and the ionosphere of Jupiter. For short intervals they have also been observed propagating from the South. The beams are regularly unidirectional and typically extend to 300 keV in energy, occasionally reaching above 600 keV. Energetic particle depletions in Callisto's wake during the downstream flybys are not at all obvious, even at low altitudes and in the wake center. The signature of the wake becomes more apparent when energetic particle observations are organized in pitch angle. In that case, pitch angle distribution minima at 90 deg can be discerned in some flybys, however, not always associated with a profound drop in the absolute signal intensity. They instead indicate that field‐aligned particle flux within the wake is higher. Outside the wake these minima continue in an energy‐dependent disturbed region toward Jupiter which seems to be at least partially collocated with Alfvén‐wing structures as predicted from magnetohydrodynamic simulation results or simple flyby geometry considerations.

Funder

Planetary Science Division

National Aeronautics and Space Administration

Publisher

American Geophysical Union (AGU)

Subject

Space and Planetary Science,Geophysics

同舟云学术

1.学者识别学者识别

2.学术分析学术分析

3.人才评估人才评估

"同舟云学术"是以全球学者为主线,采集、加工和组织学术论文而形成的新型学术文献查询和分析系统,可以对全球学者进行文献检索和人才价值评估。用户可以通过关注某些学科领域的顶尖人物而持续追踪该领域的学科进展和研究前沿。经过近期的数据扩容,当前同舟云学术共收录了国内外主流学术期刊6万余种,收集的期刊论文及会议论文总量共计约1.5亿篇,并以每天添加12000余篇中外论文的速度递增。我们也可以为用户提供个性化、定制化的学者数据。欢迎来电咨询!咨询电话:010-8811{复制后删除}0370

www.globalauthorid.com

TOP

Copyright © 2019-2024 北京同舟云网络信息技术有限公司
京公网安备11010802033243号  京ICP备18003416号-3