Anterograde Collisional Analysis of Solar Wind Ions
Anterograde Collisional Analysis of Solar Wind Ions
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DOI：
10.3847/1538-4357/accc32
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发表时间：
2023-06
期刊：
影响因子：
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通讯作者：
E. Johnson;B. Maruca;Michael T. McManus;K. Klein;E. Lichko;J. Verniero;K. Paulson;H. DeWeese;I. Dieguez;R. Qudsi;Jens H. Kasper;M. Stevens;B. Alterman;L. Iii;R. Livi;A. Rahmati;D. Larson
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文献类型：
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作者：
E. Johnson;B. Maruca;Michael T. McManus;K. Klein;E. Lichko;J. Verniero;K. Paulson;H. DeWeese;I. Dieguez;R. Qudsi;Jens H. Kasper;M. Stevens;B. Alterman;L. Iii;R. Livi;A. Rahmati;D. Larson
由于太阳风密度低、温度高，它经常表现出强烈的局部热力学平衡偏离，其中包括其组成离子的不同温度。先前的研究发现，两种最丰富的离子-质子（电离氢）和α粒子（电离氦）的温度比与库仑碰撞年龄密切相关。然而，这些先前的研究在很大程度上仅限于使用来自单个任务的观测结果。相比之下，本研究利用同期，在两个不同的航天器在两个不同的距离太阳的原位观测：帕克太阳探测器（PSP; r = 0.1-0.3 Au）和风（r = 1.0 Au）。碰撞分析，它结合了碰撞松弛和大规模扩张的方程，适用于每个PSP数据，以预测等离子体的状态更远离太阳在r = 1.0 Au。这些预测的α质子相对温度的分布与Wind观测值吻合得很好。这些结果有力地表明，在日冕之外，相对离子温度主要受库仑碰撞的影响，α粒子的优先加热主要限于日冕。
Owing to its low density and high temperature, the solar wind frequently exhibits strong departures from local thermodynamic equilibrium, which include distinct temperatures for its constituent ions. Prior studies have found that the ratio of the temperatures of the two most abundant ions—protons (ionized hydrogen) and α-particles (ionized helium)—is strongly correlated with the Coulomb collisional age. These previous studies, though, have been largely limited to using observations from single missions. In contrast, this present study utilizes contemporaneous, in situ observations from two different spacecraft at two different distances from the Sun: the Parker Solar Probe (PSP; r = 0.1–0.3 au) and Wind (r = 1.0 au). Collisional analysis, which incorporates the equations of collisional relaxation and large-scale expansion, was applied to each PSP datum to predict the state of the plasma farther from the Sun at r = 1.0 au. The distribution of these predicted α–proton relative temperatures agrees well with that of values observed by Wind. These results strongly suggest that, outside of the corona, relative ion temperatures are principally affected by Coulomb collisions and that the preferential heating of α-particles is largely limited to the corona.