In Situ Observations of Interstellar Pickup Ions from 1 au to the Outer Heliosphere.
In Situ Observations of Interstellar Pickup Ions from 1 au to the Outer Heliosphere.
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DOI：
10.1007/s11214-022-00895-2
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发表时间：
2022
影响因子：
10.3
通讯作者：
Swaczyna, P.
中科院分区：
文献类型：
--
作者：
Zirnstein, E. J.;Mobius, E.;Zhang, M.;Bower, J.;Elliott, H. A.;McComas, D. J.;Pogorelov, N., V;Swaczyna, P.
星际拾取离子是日光层太阳风等离子体中普遍存在的热力学重要组成部分。这些PUI是由太阳风中的星际中性气体电离而产生的，这些中性气体由氢、氦和微量的较重元素组成，随着日光层通过当地的星际介质。当寒冷的星际中性原子被电离时，它们形成一个与太阳风同步的高能环形光束分布。随后本征湍流和自生湍流在俯仰角上的散射以及它们与径向扩展的太阳风的平流导致了填充壳层PUI分布的形成，其密度和相对于热太阳风离子的压力随着距离太阳的增加而增大。本文回顾了在日光层中对星际PUI进行原位测量的历史。从20世纪80年代的第一次探测开始，星际PUI是通过它们的高度非热分布来识别的，截止点是太阳风速的两倍。对Pui分布壳截止点和He聚焦锥的测量有助于从近地有利位置表征星际气体的性质。He聚焦锥是由太阳重力形成的一个密度增加的顺风区。与核心太阳风相比，星际PUI的优先加热已经变得明显地存在于超热PUI尾巴的存在，PUI分布的非绝热冷却指数，以及PUI对星际激波的中介作用。与旅行者号和先驱者号航天器不同，新地平线号的太阳风环绕冥王星(SWAP)仪器正在对外日光层中的星际PUI进行唯一的直接测量，目前外日光层距离太阳或到日球层终止冲击的中途。
Interstellar pickup ions are an ubiquitous and thermodynamically important component of the solar wind plasma in the heliosphere. These PUIs are born from the ionization of the interstellar neutral gas, consisting of hydrogen, helium, and trace amounts of heavier elements, in the solar wind as the heliosphere moves through the local interstellar medium. As cold interstellar neutral atoms become ionized, they form an energetic ring beam distribution comoving with the solar wind. Subsequent scattering in pitch angle by intrinsic and self-generated turbulence and their advection with the radially expanding solar wind leads to the formation of a filled-shell PUI distribution, whose density and pressure relative to the thermal solar wind ions grows with distance from the Sun. This paper reviews the history of in situ measurements of interstellar PUIs in the heliosphere. Starting with the first detection in the 1980s, interstellar PUIs were identified by their highly nonthermal distribution with a cutoff at twice the solar wind speed. Measurements of the PUI distribution shell cutoff and the He focusing cone, a downwind region of increased density formed by the solar gravity, have helped characterize the properties of the interstellar gas from near-Earth vantage points. The preferential heating of interstellar PUIs compared to the core solar wind has become evident in the existence of suprathermal PUI tails, the nonadiabatic cooling index of the PUI distribution, and PUIs’ mediation of interplanetary shocks. Unlike the Voyager and Pioneer spacecraft, New Horizon’s Solar Wind Around Pluto (SWAP) instrument is taking the only direct measurements of interstellar PUIs in the outer heliosphere, currently out to from the Sun or halfway to the heliospheric termination shock.
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影响因子：
8.7
作者：
Bzowski, M.;Kubiak, M. A.;McComas, D. J.
通讯作者：
McComas, D. J.
影响因子：
4.9
作者：
ADAMS, TF;FRISCH, PC
通讯作者：
FRISCH, PC
影响因子：
2.8
作者：
Chalov, SV;Fahr, HJ
通讯作者：
Fahr, HJ
影响因子：
4.9
作者：
Bzowski, Maciej;Kubiak, Marzena A.;Grygorczuk, Jolanta
通讯作者：
Grygorczuk, Jolanta
影响因子：
2.8
作者：
Burlaga, LF;Ness, NF
通讯作者：
Ness, NF