64 research outputs found
Effect of Dust Evaporation and Thermal Instability on Temperature Distribution in a Protoplanetary Disk
The thermal instability of accretion disks is widely used to explain the
activity of cataclysmic variables, but its development in protoplanetary disks
has been studied in less detail. We present a semi-analytical stationary model
for calculating the midplane temperature of a gas and dust disk around a young
star. The model takes into account gas and dust opacities, as well as the
evaporation of dust at temperatures above 1000 K. Using this model, we
calculate the midplane temperature distributions of the disk under various
assumptions about the source of opacity and the presence of dust. We show that
when all considered processes are taken into account, the heat balance equation
in the region r<1 au has multiple temperature solutions. Thus, the conditions
for thermal instability are met in this region. To illustrate the possible
influence of instability on the accretion state in a protoplanetary disk, we
consider a viscous disk model with alpha parameterization of turbulent
viscosity. We show that in such a model the disk evolution is non-stationary,
with alternating phases of accumulation of matter in the inner disk and its
rapid accretion onto the star, leading to an episodic accretion pattern. These
results indicate that this instability needs to be taken into account in
evolutionary models of protoplanetary disks.Comment: Published in Astronomy Reports Vol. 67, No. 5, pp. 470-482 (2023
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