1 research outputs found
Structure and Instabilities of an Irradiated Viscous Protoplanetary Disk
We investigate the structure and the stabilities of a protoplanetary disk,
which is heated by viscous process in itself and by its central star. The disk
is set to rotate with the Keplerian velocity and has the surface density
distribution of the minimum mass solar nebula. We assume the vertical
hydrostatic equilibrium and the radiative equilibrium at each point, and solve
the two-dimensional radiative transfer equation by means of the Short
Characteristic method in the spherical coordinate in order to determine the
disk structure. Our calculation shows that at the outer region of the disk with
a distance from the central star of x>1AU the radiative heating from the inner
disk dominates the viscous heating even near the midplane. It is because of the
high temperature distribution in the optically thin surface layer and the
relatively high disk height as a consequence of the irradiation from the inner
hot region of the disk. In addition, we examine the convective and the
magnetorotational instabilities of the disk. As a result, the whole disk is
convectively stable since the dusty region is not heated by the viscous
dissipation from the midplane but by the radial radiative heating. On the other
hand, almost all the disk is magnetorotationally unstable except for the region
near the equatorial plane of from 2AU to 10AU. Finally we discuss the growth
and the size distribution of dust particles in the disk, which suggests that
there exist cm-sized particles in the surface layer, namely, in the exposed
region of the disk.Comment: 23 pages, 5 figures, accepted by ApJ (Vol. 567, 2002