Title : ( Self-similar evolutionary solutions of self-gravitating, polytropic β-viscous disks )
Authors: Shahram Abbassi , Jamshid Ghanbari , fatemeh Salehi ,Abstract
We investigate the β-prescription for viscosity in standard self-gravitating thin disks and predict that in a self-gravitating thin disk the β-model will have a different dynamical behavior compared to the well-known α-prescription.Methods. We used self-similar methods to solve the integrated equations that govern the dynamical behavior of the thin disk. Results. We present the results of self-similar solutions of the time evolution of axisymmetric, polytropic, self-gravitating viscous disks around a new-born central object. We apply a β-viscosity prescription derived from rotating shear flow experiments (ν = βr2Ω). Using reduced equations in a slow accretion limit, we demonstrate inside-out self-similar solutions after core formation in the center. Some physical quantities for β-disks are determined numerically. We compare our results with α-disks under the same initial conditions. The accretion rate onto the central object for β-disks is grater than for α-disks in the outer regions where β-disks are more efficient. Our results show that the Toomre instability parameter is less than one everywhere on the β-disk which means that in such disks gravitational instabilities can occur, so the β-disk model can be a good candidate for the origin of planetary systems. Our results show that the β-disks will decouple in the outer part of the disk where self-gravity plays an important role, in agreement with theoretical predictions.
Keywords
, accretion, accretion disks – stars: formation – planets and satellites: formation@article{paperid:1046498,
author = {Abbassi, Shahram and Ghanbari, Jamshid and Fatemeh Salehi},
title = {Self-similar evolutionary solutions of self-gravitating, polytropic β-viscous disks},
journal = {Astronomy and Astrophysics},
year = {2006},
volume = {460},
number = {2},
month = {April},
issn = {0004-6361},
pages = {357--363},
numpages = {6},
keywords = {accretion; accretion disks – stars: formation – planets and satellites: formation},
}
%0 Journal Article
%T Self-similar evolutionary solutions of self-gravitating, polytropic β-viscous disks
%A Abbassi, Shahram
%A Ghanbari, Jamshid
%A Fatemeh Salehi
%J Astronomy and Astrophysics
%@ 0004-6361
%D 2006