最近，SDO/AIA直接观测到沿着日冕磁漏斗开放场传播的快磁声波; 其产生的物理过程还不明确。目前，本研究所太阳风与行星际物理课题组客座研究员杨利平及其合作者，利用数值模拟的方法给出日冕磁重联激发快波的产生过程， 即日冕闭合磁圈受光球剪切运动驱动，与邻近开放磁场发生多重x-lines重联，产生高速等离子团。该等离子团迅速撞击出流区，激发快波。所激发快波性质 与SDO卫星AIA观测到的快波相似。该工作发表于天体物理学杂志。
Liping Yang et al. 2015 ApJ 800 111 doi:10.1088/0004-637X/800/2/111
NUMERICAL SIMULATION OF FAST-MODE MAGNETOSONIC WAVES EXCITED BY PLASMOID EJECTIONS IN THE SOLAR CORONA
Liping Yang1,2, Lei Zhang1, Jiansen He1, Hardi Peter3, Chuanyi Tu1, Linghua Wang1, Shaohua Zhang4, and Xueshang Feng2
1School of Earth and Space Sciences, Peking University, 100871 Beijing, China 2 SIGMA Weather Group, State Key Laboratory for Space Weather, Center for Space Science and Applied Research, Chinese Academy of Sciences, 100190 Beijing, China 3 Max-Planck-Institut für Aeronomie, Max-Planck-Strasse, D-37191 Katlenburg-Lindau, Germany 4 Center of Spacecraft Assembly Integration and Test, China Academy of Space Technology, Beijing 100094, China
The Atmospheric Imaging Assembly instrument on board the Solar Dynamics Observatory has directly imaged the fast-propagating magnetosonic waves (FMWs) successively propagating outward along coronal magnetic funnels. In this study we perform a numerical investigation of the excitation of FMWs in the interchange reconnection scenario, with footpoint shearing flow being used to energize the system and drive the reconnection. The modeling results show that as a result of magnetic reconnection, the plasma in the current sheet is heated up by Joule dissipation to ~10 MK and is ejected rapidly, developing the hot outflows. Meanwhile, the current sheet is torn into plasmoids, which are shot quickly both upward and downward. When the plasmoids reach the outflow regions, they impact and collide with the ambient magnetic field there, which consecutively launches FMWs. The FMWs propagate outward divergently away from the impact regions, with a phase speed of the Alfvén speed of ~1000 km s–1. In the k – ω diagram of the Fourier wave power, the FMWs display a broad frequency distribution with a straight ridge that represents the dispersion relation. With the WKB approximation, at the distance of 15 Mm from the wave source region, we estimate the energy flux of FMWs to be E ~ 7.0 × 106 erg cm–2 s–1, which is ~50 times smaller than the energy flux related to the tube-channeled reconnection outflow. These simulation results indicate that energetically and dynamically the outflow is far more important than the waves.
Keywords
magnetic reconnection; Sun: corona; waves
Dates
Issue 2 (2015 February 20)
Received 2013 November 25, accepted for publication 2014 December 23
Published 2015 February 18
