Theoretical Study of Magnetohydrodynamic Phenomena in Active Celestial Objects

该项目的目的是组织对各种磁流体现象(重联、发电机、MHD湍流、MHD波、喷流、吸积等)的合作研究。为了实现这些目标，我们于1992年9月在热海举办了一次关于宇宙MHD现象的研讨会。60多人参加了会议。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际等离子体的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、地核和行星核中的对流和发电机、涡旋重联、磁重联和地球磁层中的开尔文-亥姆霍兹不稳定性、加速度和动态…。对太阳风、太阳磁流体动力学现象(特别是Yohkoh观测到的太阳日冕中的磁重联和动力学现象)、黑洞磁层中的喷流形成、恒星形成区的磁场、星际空间中的MHD现象、星际磁场等方面的较多研究成果总结如下：(1)我们比较了发生在地球磁层尾部和日冕中的磁重联，发现等离子体的形成和加速在这两种情况下都起到了关键作用。地球和太阳磁场重联的2D和3D MHD数值模拟也证实了这一点。(2)通过将Yohkoh拍摄的日冕图像与盘星系的高分辨率光学图像进行详细比较，在盘状星系中发现了各种类似于日冕动力学现象的动力学现象(环、喷流、尖晶石)。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。较少

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