| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1988: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1987: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Research Abstract |
Developing the 3D MHD code, I have investigated the equilibrium structures of rotating, magnetized isothermal clouds under various conditions, and also have examined their evolution in consideration of magnetic field and angular momentum loss due to the ambipolar diffusion.
Till the present work, the equilibrium structures of rotating clouds without magnetic field or those of magnetized clouds without rotation have been studied. In this research, I have explored the equilibria of isothermal clouds considering both the rotation and magnetic field by using the MHD code. Further, the evolution of them has been followed. There are two kinds of equilibrium solutions for a fixed mass cloud: one is stable and the other is unstable. These two solutions coincide when the cloud has a critical mass, above which there are no equilibrium solutions for a given magnetic field and angular momentum distribution. The dependence of this critical mass upon magnetic field strength and total angular momentum has been made clear, and we have got a simple algebraic equation for it.Utilizing this equation, we can easily see the stability of clouds and magnetic field strength for o bserved clouds.
It is shown that the evolution of rotating, magnetized clouds is rather simple. At the innner region, the magnetic pressure dominates when the angular momentum loss is included and at the outer region the centrifugal force dom-inates. This results in the collapse of inner region to stars with keeping the outer, rotating disk. This evolutionary behavior sensitively depends upon the loss rate of magnetic field due to ambipolar diffusion and associated angular momentum loss. At present, the details of these physical essence are explored by means of a simple model.
The stability of clouds and configuration of interstellar magnetic field are strongly coupled, and their coupling will affect the formation and equilibrium figures of clouds. This is an important problem to be examined more.
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