Dynamics of solar coronal loops -: I.: Condensation in cool loops and its effect on transition region lines

被引:0
作者
Müller, DAN
Hansteen, VH
Peter, H
机构
[1] Kiepenheuer Inst Sonnenphys, D-79104 Freiburg, Germany
[2] Univ Oslo, Inst Theoret Astrophys, N-0315 Oslo, Norway
关键词
Sun : corona; Sun : transition region; Sun : UV radiation;
D O I
10.1051/0004-6361:20031328
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We report numerical calculations of the condensation of plasma in short coronal loops, which have several interesting physical consequences. Firstly, we propose a connection between small, cool loops (T < 10(6) K), which constitute one of the basic components of the solar transition region, and prominences, in the sense that the same physical mechanism governs their dynamics: Namely the onset of instability and runaway cooling due to strong radiative losses. Secondly, we show that the temporal evolution of these loop models exhibits a cyclic pattern of chromospheric evaporation, condensation, motion of the condensation region to either side of the loop, and finally loop reheating with a period of 4000 - 8000 s for a loop of 10 Mm length. Thirdly, we have synthesized transition region lines from these calculations which show strong periodic intensity variations, making condensation in loops a candidate to account for observed transient brightenings of solar transition region lines. Remarkably, all these dynamic processes take place for a heating function which is constant in time and has a simple exponential height dependence.
引用
收藏
页码:605 / 613
页数:9
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