Mass Motions and Plasma Properties in the 107 K Flare Solar Corona
Mass Motions and Plasma Properties in the 107 K Flare Solar Corona
复制标题
107 K 耀斑日冕中的质量运动和等离子体特性
DOI：
10.1086/344524
复制
发表时间：
2003
期刊：
影响因子：
--
通讯作者：
W. Curdt
中科院分区：
文献类型：
--
作者：
E. Landi;U. Feldman;D. Innes;W. Curdt
在目前的工作中，我们分析了太阳紫外线测量发射辐射（SUMER）观测的一个太阳临边耀斑，发生在1999年5月9日。分析的数据涵盖了大约6.4小时的时间跨度，在此期间，一个M-7.6耀斑爆发和衰减的视野。两个选定的区域沿着SUMER狭缝已被认为是定量分析。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化。为了实现这一点，我们使用具有2.5 × 106至2 × 107 K范围内的形成温度的线，从中我们推导出净质量运动和非热速度，并将它们与不受耀斑活动影响的周围等离子体的性质进行比较。为了了解燃烧等离子体和周围材料的物理条件，我们推导出电子温度，电子密度，和发射等离子体的发射措施。我们发现，散装运动，最初的订单数百公里每秒在两个方向上，衰减在10分钟内从耀斑发作;非热速度衰减到preflare值约30公里s-1在不到2小时的最大值约100公里s-1在耀斑发作。测量的电子密度似乎并没有改变活动期间，而耀斑等离子体温度稳步衰减到preflare值。的温度演变是一致的辐射冷却等离子体，虽然不确定性的测量耀斑等离子体的热能的变化，防止一个明确的结论上可能的持续加热的耀斑等离子体。
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 × 106 to 2 × 107 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.