Theoretical Study of Magnetohydrodynamic Phenomena in Active Celestial Objects

该项目的目的是组织对许多活动天体观测到的各种磁流体动力学现象（重联、发电机、MHD湍流、MHD波、射流、吸积等）的合作研究，并鼓励在不同领域（如天文学、核聚变、等离子体物理、地球物理、流体力学）研究类似物理过程的研究人员之间的积极交流。为了实现这些目标，我们于1992年9月在热海举行了一次关于宇宙MHD现象的专题讨论会。超过60人参加了仪式。我们不仅讨论了理论研究结果，还讨论了从聚变等离子体到星系间等离子体等各种宇宙等离子体的观测结果。我们讨论的具体项目有：聚变等离子体中的发电机过程、地球和行星核心中的对流和发电机过程、地球磁层中的涡旋重联、磁重联和开尔文-亥姆霍兹不稳定性、加速和动力学、太阳风的更多研究、太阳中的磁流体动力学现象（特别是YOHKOH观测到的日冕中的磁重联和动力学现象）、黑洞磁层中的射流形成、恒星形成区的磁场。星际空间中的MHD现象，星系间磁场等。这些研究得到的主要结果总结如下：(1)我们比较了发生在地球磁层尾部和太阳日冕的磁重联，发现等离子体的形成和加速在这两种情况下都起着关键作用。地球和太阳磁场重联的二维和三维MHD数值模拟也证实了这一点。(2)通过对YOHKOH拍摄的太阳日冕图像与盘状星系高分辨率光学图像的详细对比，发现了盘状星系中各种类似太阳日冕动态现象（环、喷流、棘柱）。对盘状星系和太阳中的帕克不稳定性也进行了数值模拟，这解释了盘状星系和太阳中磁环的形成。少

The purposes of this project are to organize cooperative research on various magnetohydrodynamic phenomena (reconnection, dynamo, MHD turbulence, MHD wave, jet, accretion, etc.) observed in many active celestial objects, and to encourage active communication between researchers, who are studying similar physical processes, in different fields (e.g., astronomy, nuclear fusion, plasma physics, geophysics, fluid mechanics).In order to accomplish these objectives, we held a symposium on cosmic MHD phenomena at Atami in September, 1992. More than 60 people attended. We discussed not only theoretical research results but also observational results in relation to various cosmical plasmas ranging from fusion plasmas to intergalactic plasmas. Specific items we discussed are; dynamo processes in fusion plasmas, convection and dynamo in terrestrial and planetary cores, vortex reconnection, magnetic reconnection and Kelvin-Helmholtz instability in terrestrial magnetosphere, acceleration and dynami … More cs of solar wind, magnetohydrodynamic phenomena in the Sun (especially on magnetic reconnection and dynamic phenomena in the solar corona observed by YOHKOH), jet formation in black hole magnetosphere, magnetic field in star forming regions, MHD phenomena in interstellar space, intergalactic magnetic fields, etc.Major results obtained by these researches are summarized in the following;(1) We compared magnetic reconnections occurring in the tail of terrestrial magnetosphere and in the solar corona, and found that the formation and acceleration of plasmaids play a key role in both cases. This has also been confirmed by 2D and 3D MHD numerical simulations of magnetic reconnection for both terrestrial and solar cases.(2) Various dynamic phenomena (loops, jets, spincules) similar to solar coronal dynamic phenomena have been discovered in disk galaxies from detailed comparison between solar coronal images taken by YOHKOH and high resolution optical images of disk galaxies. Numerical simulations have also been done for the Parker instability both in disk galaxies and in the Sun, which explains the formation of magnetic loops in disk galaxies and the Sun. Less