HEATING AND COOLING PROTOSTELLAR DISKS

Magnetohydrodynamics of Protostellar Disks

The magnetohydrodynamical behavior (MHD) of accretion disks is reviewed. A detailed presentation of the fundamental MHD equations appropriate for protostellar disks is given. The combination of a weak (subthermal) magnetic field and Keplerian rotation is unstable to the magnetorotational instability (MRI), if the degree of ionization in the disk is sufficiently high. The MRI produces enhanced a...

Transport Processes in Protostellar Disks

Photoevaporation of Protostellar Disks Iv. Externally Illuminated Disks

By means of numerical simulations we investigate the photoevaporation of protostellar disks. Here we concentrate on the evolution of disks under the influence of an external Lyman continuum radiation field. The morphological evolution is illustrated in detail for the case of a relatively massive disk exposed to a modest ionizing flux. Cometary tails develop and break off into filaments which le...

Dust Evolution in Protostellar Accretion Disks

We calculated the collapse of a / r 2 density peaked, slowly rotating molecular cloud core by 2D numerical radiation hydrodynamical simulations. The dynamics of the dust grains is calculated applying a multicomponent uid model. Acceleration by the radiation eld, coupling to the gas component by dynamical friction, coagulation and shattering of the grains is included. Relative velocities between...

Radiation Induced Warping of Protostellar Accretion Disks

We examine the consequences of radiatively driven warping of accretion disks surrounding pre-main-sequence stars. These disks are stable against warping if the luminosity arises from a steady accretion flow, but are unstable at late times when the intrinsic luminosity of the star overwhelms that provided by the disk. Warps can be excited for stars with luminosities of around 10L⊙ or greater, wi...