THEORETICAL RESTRICTIONS ON ACCRETION DISKS

We construct a standard thin disk model taking into account the pressu re from both gas and radiation, the opacity contributed by both electr on scattering and absorption, and the gravity from both a central obje ct and a disk. A simple and powerful technique for solving the non-lin ear equations is presented. Through a numerical algorithm for the two equationl for beta, gamma, xi, all the disk quantities are expressed a s the analytical function of beta, gamma, xi. We also discuss the solu tions in the limit cases beta --> 0, beta --> 1 and the parameter rang e of the linear approximation. From the numerical solutions and limit analyses, we found that it is not necessary to include the self-gravit y of the disk.