Bright points and subflares in ultraviolet lines and X-rays

被引:5
|
作者
Rovira, M
Schmieder, B
Démoulin, P
Simnett, GM
Hagyard, MJ
Reichmann, E
Tandberg-Hanssen, E
机构
[1] Consejo Nacl Invest Cient & Tecn, Inst Astron & Fis Espacio, RA-1428 Buenos Aires, DF, Argentina
[2] Observ Paris, Sect Meudon, DASOP, URA2080, F-92195 Meudon, France
[3] Univ Oslo, Inst Theoret Astrophys, N-0315 Oslo, Norway
[4] Univ Birmingham, Birmingham B15 2TT, W Midlands, England
[5] NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA
来源
ASTROPHYSICAL JOURNAL | 1999年 / 510卷 / 01期
关键词
Sun : flares; Sun : UV radiation; Sun; x-rays; gamma rays;
D O I
10.1086/306566
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We have analyzed an active region which was observed in H alpha (Multichannel Subtractive Double Pass Spectrograph), in UV lines (SMM/UVSP), and in X-rays (SMM/HXIS). In this active region there were only a few subflares and many small bright points visible in UV and in X-rays. Using an extrapolation based on the Fourier transform, we have computed magnetic field lines connecting different photospheric magnetic polarities from ground-based magnetograms. Along the magnetic inversion lines we find two different zones: (1) a high-shear region (> 70 degrees) where subflares occur, and (2) a low-shear region along the magnetic inversion line where UV bright points are observed. In these latter regions the magnetic topology is complex with a mixture of polarities. According to the velocity field observed in the Si IV lambda 1402 line and the extrapolation of the magnetic field, we notice that each UV bright point is consistent with emission from low-rising loops with downflows at both ends. We notice some hard X-ray emissions above the bright-point regions with temperatures up to 8 x 10(6) K, which suggests some induced reconnection due to continuous emergence of new flux. This reconnection is also enhanced by neighboring subflares.
引用
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页码:474 / 484
页数:11
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