Chromospheric evaporation velocities in solar flares
Chromospheric evaporation velocities in solar flares
复制标题
太阳耀斑中的色层蒸发速度
DOI：
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发表时间：
1984
期刊：
影响因子：
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通讯作者：
A. Mcclymont
中科院分区：
文献类型：
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作者：
G. Fisher;R. Canfield;A. Mcclymont
我们证明了耀斑环色球蒸发速度的上限约为2.35c/次S/，其中c/次S/是蒸发物质中的声速。观测到的上升速度大于这一极限将意味着存在额外的非流体动力。非热高能电子碰撞加热(厚靶模型)的流体力学计算给出了在上限附近的上升速度(或=3×10/sup 10/ergs S/sup-1/cm/sup-2/)能量流量值。在较适中的流量(10/超9/-10/超10/尔格斯S/超-1/)下，“热”和“厚靶”模型的最大速度都在上限的10%到30%之间。从太阳极大任务(Antonucci和Dennis)观测到的假定蒸发速度似乎在上限的10%到25%之间。当同时考虑蒸发等离子体的温度和速度时，能量通量在3×10/sup 9/和10/sup 10/ergs S/sup-1/cm/sup-2/之间的“热”模型与这些观测结果最为一致。
We show that an upper limit to chromosphere evaporation velocities in solar flare loops is approximately 2.35c/sub s/, where c/sub s/ is the sound speed in the evaporated material. Observed upward velocities greater than this limit would imply the existence of additional nonhydrodynamic forces. Hydrodynamic calculations of collisional heating by nonthermal energetic electrons (thick-target model) yield upward velocities near the upper limit at large (> or =3 x 10/sup 10/ ergs s/sup -1/ cm/sup -2/) energy flux values. At more modest fluxes (10/sup 9/-10/sup 10/ ergs s/sup -1/), both 'thermal' and 'thick-target' models yield maximum velocities that are between 10% and 30% of the upper limit. Observations of postulated evaporation velocities from the Solar Maximum Mission (Antonucci and Dennis) appear to be between 10% and 25% of the upper limit. When both temperature and velocity of the evaporated plasma are considered, the 'thermal' model with energy fluxes between 3 x 10/sup 9/ and 10/sup 10/ ergs s/sup -1/ cm/sup -2/ is found to be most consistent with these observations.