Observation and Theory of Magnetic Fields in Spiral Galaxies.

(1)利用射电极化数据，在螺旋星系中发现了对称的螺旋磁场。尽管导电气体有不同的旋转，它们还是松散地缠绕在圆盘上。这与20年前让许多天文学家为旋臂着迷的难题是一样的。我们通过考虑星际磁场的湍流扩散和盘晕气体中垂直扩散的发电机作用来解决这个问题：由微分旋转产生的紧密扭曲的磁场通过湍流运动扩散到星系晕中，并被发电机作用新产生的松散扭曲的磁场所取代。(2)当各种介质的非线性动力学得到更全面的发展时，上述问题的最终解才会得到。为了实现这一目标，我们研究了正弦形式离散双正弦-戈登方程中的扭结-反扭结态和呼吸模式，DNA的局部结构波动，以及量子自旋系统的解耦细胞法蒙特卡罗模拟。我们已经发现了一些在连续或/和离散介质中产生的混沌和非线性全局结构的例子。讨论了在天体物理学中的可能应用。(3)热动力学和水磁学应用于旋转的气体盘。一般的稳定性和不稳定性分析发现了一种新的模态，这种模态在气体介质的微分旋转中总是不稳定的。认为盘状气体的湍流运动就是从这种不稳定性中产生和发展起来的。如果这是真的，我们可能是第一个发现x射线发射吸积气体< α > p型粘度的基本过程。(4)用CO (J=1-0) < λ > =2.6 mm射电辐射观测到棒状星系M83中的分子气体。发现了分子气体的非圆运动和不对称凝聚。重力扭矩在M83中起作用。

(1) Bisymetric spiral magnetic fields have been found in spiral galaxies from radio polarization data. They are wound rather loosely in the disk in spite of the differential rotation of electrically-conducting gas. This is the same dilemma as the one that tantalized many astronomers for the spiral arms two decades ago. We solved this problem by taking into account both the turbulent diffusion of interstellar magnetic fields and the associated dynamo action in the disk-halo gas in vertical spread: The tightly-twisted magnetic fields, generated by the differential rotation, diffuse out into the galactic halo by the turbulent motion and are replaced by the loosely-twisted ones newly generated by the dynamo action.(2) Final solution of the above problem is to be obtained when the nonlinear dynamics of various kinds of media are more generally developed. As several steps towards this goal, we have worked on the kink-antikink states and breather-like modes in sine-form discrete double Sine-Gordon equation, the local structural fluctuation of DNA, and the decoupled cell method Monte Carlo simualtion for quantum spin system. We have found some examples of chaos and nonlinear global structures generated in continuous or/and discrete media. A possible appication to astrophysics was discussed.(3) Therodynamics and hydromagnetics are applied to rotating gaseous disks. A general stabiltity-and-instability analysis has found a new type of mode which is always unstable in the gaseous media in differential rotation. It is suggested that the turbulent motion of disk gas is initiated and developed from this instabiltiy. If it is true, we could be the first to find a basic process for the <alpha> P-type viscosity in the X-ray emitting accretion gas.(4) Molecular gas in the barred galaxy M83 has been observed by <lambda> =2.6 mm radio emission of CO (J=1-0). Noncircular motion and asymmetyric condensation of molecular gas are found. Gravitational torque is operative in M83.