Invited by the Research Center for Galaxy and Cosmology of Shanghai Astronomical Observatory (SHAO), Prof. James M. Stone from Princeton University visited SHAO during Sept. 23 – 27 and gave a colloquium talk in the Lecture Hall.

     Prof. Stone started from the basic equations of magnetohydrodynamics of accretion disks to their recent study in this regime. Next, he mainly focused on the results and application of the recent numerical studies to radiation dominated disks. His team found that a radiation dominated disk always undergoes a thermal runaway, either collapsing or expanding over several thermal times.  He further pointed out that the physics of this runaway is quite different from the classical linear instability in radiation dominated alpha disks predicted by Shakura and Sunyaev. He discussed the requirements for saturation of the runaway. Future work to solve this problem were also presented at the end of his talk.

     Prof. Stone works in the Department of Astrophysical Sciences at Princeton University, and he is also the director of the Princeton Institute for Computational Science and Engineering (PICSciE). Prof. Stone's major research interest is the numerical methods application to nonlinear and multidimensional fluid dynamics in astrophysical systems, such as accretion flows onto black holes, exoplanet formation, e.t.c. During his visit, professors and students from the Research Center for Galaxy and Cosmology of SHAO have further discussions with Prof. Stone, about their research and possible collaboration.