Star Formation
Wilhelm Kley
Universität Tübingen
The theory of star formation deals with the formation of stars and
possibly their planetary systems.
A model for the FU Ori Outburst phenomenon
During their formation protostars may undergo very intense time variability
in their luminosity. We performed time dependent two-dimensional
Radiation Hydrodynamical Models
of the inner region (see Boundary Layer) of an Accretion Disk.
The details are published in
ApJ 518, 833 (1999).
Related Animation:
(
Movie)
The Boundary Layer
The interaction region
of the disk with the central star, the Boundary Layer, is of great importance
in accretion disk theory since up to half of the accretion luminosity
can be released from a very small region.
Together with Doug Lin
at the University of California at Santa Cruz
(UCSC)
we studied the detailed structure of this inner region region of the disk
in a protostellar context.
The details are published in
ApJ 461, 933 (1996).
Causal Viscosity
In one-dimensional models we studied the effects of a causal implementation of viscosity
for boundary layer calculations.
The details are published in
MNRAS 285, 239 (1997).
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Convection in protostellar Accretion Disks
The temperature and densities in a protostellar disk are such that the
vertical stratification within some radial range
becomes unstable to thermal convection. It has
been suggested that this convection is a possible mechanism to generate
turbulence in the disk. Hence it may play an important role in contributing
to the angular momentum transport in disks. Together with
Doug Lin
(UCSC)
and
John Papaloizou
from the Queen Mary and Westfield College
(QMW)
in London I studied the two-dimensional structure of convectively unstable
disks.
We found that in this case the induced angular momentum transport
tends to be into the negative radial direction.
The details are published in
ApJ 416, 679 (1993).
We also investigated the three-dimensional case by a linear analysis and
found that in this case there may be modes which are able to transport
angular momentum outwards
ApJ 416, 689 (1993).