太阳耀斑和亮点中双向出流的成像观测研究

Magnetic reconnection is an important model of solar eruption phenomena, such as solar flares, bright points and explosive event in solar atmosphere. To look for the observational evidence of magnetic reconnection is a hot topic in solar physics, astrophysics and so on. There is no way to measure the magnetic field in the solar corona at present, while the magnetic reconnection takes place there. It is an interesting work to look for the indirect evidence after magnetic reconnection for solar physics researcher. Actually, the bi-directional outflow is thought to be one of the indirect evidences. According to the reconnection model, the particles (electrons and ions) are accelerated from the reconnection region and move upward and downward simultaneously. They are so-welled bi-directional outflows. They could produce radiation or excite waves or drive the mass movement when these outflows propagate through the surrounding plasma. Theoretically, it is widely accepted that the solar flare, bright points and explosive events are thought to be produced by the reconnection model. The current sheet between the two kinds coronal X-ray sources above flare loops are thought to be the accelerated region for the outflows. Meanwhile, the bi-directional outflows produce both the blue and red-shifted components in the explosive events from the ultraviolet spectral observations, which supports that the explosive events are produced by the reconnection model. Solar Dynamic Observatory (SDO) provides unprecedented capabilities for spatially investigating the bi-directional outflows along the magnetic loops with a high temporal and spatial resolution at different wavelengths from the chromosphere to solar corona. In this proposal, the main aim is to imaging study the bi-directional outflows in solar flares or bright points. Meanwhile, the bi-directional inflows would be studied as well. In the previous time, we have analyzed the solar flares and bright points respectively. Imaging study the bi-directional outflows in solar flares and bright points are helpful to understand the magnetic reconnection model. Meanwhile, the results would be an observational constraint on the reconnection model.

磁重联是太阳大气中的耀斑和亮点等爆发现象的主流模型之一。到目前为止，太阳大气中的磁场不能直接被观测到，因而我们无法得到磁场重联的直接证据。那么寻求磁场重联模型的间接证据一直以来是太阳物理甚至天体物理界科学研究的热点之一。研究发现，双向出流被认为是磁场重联模型的最重要的间接证据之一。根据重联模型，带电粒子在重联区被加速后会同时向着相反方向逃逸，这就是所谓的双向出流，其速度与当地的阿尔芬速度相当。当这些被加速双向粒子流穿过当地的等离子体时会产生电磁辐射或者激发某些波动现象等能被观测到。和双向粒子出流类似，这些现象也具有双向性、同时性、空间上的对称性等特点。因此，这些双向辐射现象就被认为是磁场重联模型的一个可观测的间接证据。本项目的主要研究内容就是利用目前国际上最先进的空间太阳望远镜(SDO)的观测资料，成像研究耀斑爆发或亮点中磁重联产生的双向出流的辐射轨迹或波动现象的物理特性。

磁重联是太阳大气中的耀斑和亮点等爆发现象的主流模型之一。根据模型，双向出流被认为是磁场重联的最重要的间接证据之一。根据重联模型，带电粒子在重联区被加速后会同时向着相反方向逃逸，这就是所谓的双向出流，其速度与当地的阿尔芬速度相当。当这些被加速双向粒子流穿过当地的等离子体时会产生电磁辐射或者激发某些波动现象等能被观测到。和双向粒子出流类似，这些现象也具有双向性、同时性、空间上的对称性等特点。因此，这些双向辐射现象就被认为是磁场重联模型的一个可观测的间接证据。本项目的主要研究内容就是利用目前国际上最先进的空间太阳望远镜(SDO)和地面望远镜的观测资料，成像研究数十个太阳耀斑爆发或亮点中磁重联产生的双向出流的辐射轨迹或波动现象的物理特性。研究发现，在太阳耀斑和亮点事例中，确实存在双向出流的等离子体，他们的辐射轨迹被望远镜成功观测到。根据重联模型，他们的出发地就是磁场重联地方，双向出流的等离子可以在日冕的不同层次被观测到，出流速度大约百公里每秒的量级。同时，这些双向出流有一定重复性，在不同的事例中周期不同，周期平均在分钟量级。因此，磁场重联的周期性研究是未来研究的一个有意义的方向。