University of Maryland, College Park, Maryland 20742, USA.
School of Space Research, Kyung Hee University, Yongin, Gyeonggi 17104, Korea.
Phys Rev Lett. 2019 Oct 4;123(14):145101. doi: 10.1103/PhysRevLett.123.145101.
Reliable models of the solar wind in the near-Earth space environment may constrain conditions close to the Sun. This is relevant to NASA's contemporary innerheliospheric mission Parker Solar Probe. Among the outstanding issues is how to explain the solar wind temperature isotropy. Perpendicular and parallel proton and electron temperatures near 1 AU are theoretically predicted to be unequal, but in situ observations show quasi-isotropy sufficiently below the instability threshold condition. This has not been satisfactorily explained. The present Letter shows that the dynamical coupling of electrons and protons via collisional processes and instabilities may contribute toward the resolution of this problem.
可靠的近地空间太阳风模型可能会约束接近太阳的条件。这与美国宇航局（NASA）当前的内日球层帕克太阳探测器任务有关。尚未解决的问题之一是如何解释太阳风温度各向同性。理论上预测，在 1 AU 附近的质子和电子的垂直和平行温度应该是不相等的，但原位观测显示，在低于不稳定性阈值条件下，太阳风具有近乎各向同性。这一点尚未得到令人满意的解释。本研究表明，通过碰撞过程和不稳定性对电子和质子的动力学耦合可能有助于解决这一问题。
