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首页> 外文期刊>The Astrophysical journal >MASS MOTIONS AND PLASMA PROPERTIES IN THE 10~7 K FLARE SOLAR CORONA
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MASS MOTIONS AND PLASMA PROPERTIES IN THE 10~7 K FLARE SOLAR CORONA

机译：10〜7 K耀斑日冕的质量运动和等离子体性质

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摘要

In the present work, we analyze Solar Ultraviolet Measurement of Emitted Radiation (SUMER) observations of a solar limb flare that occurred on 1999 May 9. The analyzed data cover a time span of around 6.4 hr, during which an M-7.6 flare erupted and decayed in the field of view. Two selected regions along the SUMER slit have been considered for quantitative analysis. The main purpose of the present analysis is to measure the mass motions and the nonthermal velocities of the postflare plasmas and their temporal evolution. To achieve this we use lines having formation temperatures in the 2.5 x 10~6 to 2 x 10~7 K range from which we derive net mass motions and nonthermal velocities and compare them with the properties of the surrounding plasma not affected by the flare activity. To understand the physical conditions of the flaring plasma and of the surrounding material, we derive electron temperature, electron density, and emission measures of the emitting plasma. We find that bulk motions, initially of the order of several hundreds of kilometers per second in both directions, decay within 10 minutes from the flare onset; nonthermal velocities decay to preflare values of around 30 km s~(-1) in less than 2 hr from the maximum value of around 100 km s~(-1) at flare onset. The measured electron density does not seem to change during activity, while the flare plasma temperature steadily decays to preflare values. The temperature evolution is consistent with a radiatively cooling plasma, although the uncertainties associated to the measurement of the variation of thermal energy of the flare plasma prevent a definitive conclusion on possible continuous heating of the flaring plasma.
机译：在当前的工作中，我们分析了发生在1999年5月9日的太阳四肢耀斑的太阳紫外线辐射测量（SUMER）观测结果。分析的数据涵盖大约6.4 hr的时间跨度，在此期间爆发了M-7.6耀斑，在视野中衰减了。已考虑沿SUMER缝隙选择两个区域进行定量分析。本分析的主要目的是测量耀斑后等离子体的质量运动和非热速度及其时间演变。为此，我们使用地层温度在2.5 x 10〜6到2 x 10〜7 K范围内的线，从中得出净质量运动和非热速度，并将其与不受火炬活动影响的周围等离子体的性质进行比较。为了了解扩口等离子体和周围材料的物理条件，我们导出了电子温度，电子密度和发射等离子体的发射量度。我们发现，从火炬爆发起，在10分钟内，两个方向的初始运动都以每秒几百公里的速度开始衰减。非火力速度在爆发后不到2小时内便从约100 km s〜（-1）的最大值衰减到约30 km s〜（-1）的耀斑前值。在活动期间，测得的电子密度似乎没有变化，而耀斑的等离子体温度稳定地下降到耀斑前的值。温度的变化与辐射冷却等离子体是一致的，尽管与火炬等离子体热能变化的测量相关的不确定性妨碍了对火炬等离子体可能连续加热的明确结论。

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