Strong Preferential Ion Heating is Limited to within the Solar Alfvén Surface
Strong Preferential Ion Heating is Limited to within the Solar Alfvén Surface
复制标题
强优先离子加热仅限于太阳阿尔芬表面内
DOI：
10.3847/2041-8213/ab1de5
复制
发表时间：
2019
期刊：
影响因子：
--
通讯作者：
K. Klein
中科院分区：
文献类型：
--
作者：
J. Kasper;K. Klein
由库仑热化引起的太阳风氦氢温度比的衰减可以用来测量离太阳有多远发生强烈的优先离子加热。以前的工作已经表明，导致质量比例温度的优先离子加热区平均从太阳延伸约20-40R⊙。在这里，我们观察这个区域外边界随时间的运动，并将其与其他物理上有意义的距离进行比较。我们报道，在太阳活动周期内，边界与阿尔芬点同步运动，随着太阳活动而收缩和膨胀，相关系数优于0.95，均方根差为4.23R⊙。强烈的择优离子加热显然主要活跃在阿尔芬表面以下。为了确定潜在的优先加热机制，有必要对Alfvén表面下的局部等离子体条件进行现场测量。我们预测，帕克太阳探测器(PSP)将是第一个直接观测到这种加热作用的航天器，但在发射后仅几年，随着活动的增加，区域扩大，PSP的近日点下降。
The decay of the solar wind helium-to-hydrogen temperature ratio due to Coulomb thermalization can be used to measure how far from the Sun strong preferential ion heating occurs. Previous work has shown that a zone of preferential ion heating, resulting in mass-proportional temperatures, extends about 20–40 R⊙ from the Sun on average. Here we look at the motion of the outer boundary of this zone with time and compare it to other physically meaningful distances. We report that the boundary moves in lockstep with the Alfvén point over the solar cycle, contracting and expanding with solar activity with a correlation coefficient of better than 0.95 and with an rms difference of 4.23 R⊙. Strong preferential ion heating is apparently predominately active below the Alfvén surface. To definitively identify the underlying preferential heating mechanisms, it will be necessary to make in situ measurements of the local plasma conditions below the Alfvén surface. We predict that the Parker Solar Probe (PSP) will be the first spacecraft to directly observe this heating in action, but only a couple of years after launch as activity increases, the zone expands, and PSP’s perihelion drops.
影响因子：
19.6
作者：
Grant, Samuel D. T.;Jess, David B.;Hewitt, Rebecca L.
通讯作者：
Hewitt, Rebecca L.