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dc.contributor.author Michael, S. en
dc.contributor.author Steiman-Cameron, T.Y. en
dc.contributor.author Durisen, R.H. en
dc.contributor.author Boley, A.C. en
dc.date.accessioned 2014-10-27T17:12:07Z en
dc.date.available 2014-10-27T17:12:07Z en
dc.date.issued 2012 en
dc.identifier.citation Michael, S., Steiman-Cameron, T. Y., Durisen, R. H., & Boley, A. C. (2012). Convergence studies of mass transport in disks with gravitational instabilities. I. the constant cooling time case. Astrophysical Journal, 746(1). http://dx.doi.org/10.1088/0004-637X/746/1/98 en
dc.identifier.uri http://hdl.handle.net/2022/19066
dc.description.abstract We conduct a convergence study of a protostellar disk, subject to a constant global cooling time and susceptible to gravitational instabilities (GIs), at a time when heating and cooling are roughly balanced. Our goal is to determine the gravitational torques produced by GIs, the level to which transport can be represented by a simple α-disk formulation, and to examine fragmentation criteria. Four simulations are conducted, identical except for the number of azimuthal computational grid points used. A Fourier decomposition of non-axisymmetric density structures in cos ($m\phi$), sin ($m\phi$) is performed to evaluate the amplitudes $A_{m}$ of these structures. The $A_{m}$, gravitational torques, and the effective Shakura & Sunyaev α arising from gravitational stresses are determined for each resolution. We find nonzero $A_{m}$ for all $m$-values and that $A_{m}$ summed over all $m$ is essentially independent of resolution. Because the number of measurable $m$-values is limited to half the number of azimuthal grid points, higher-resolution simulations have a larger fraction of their total amplitude in higher-order structures. These structures act more locally than lower-order structures. Therefore, as the resolution increases the total gravitational stress decreases as well, leading higher-resolution simulations to experience weaker average gravitational torques than lower-resolution simulations. The effective $\alpha$ also depends upon the magnitude of the stresses, thus $\alpha_{\text{eff}}$ also decreases with increasing resolution. Our converged $\alpha_{\text{eff}}$ is consistent with predictions from an analytic local theory for thin disks by Gammie, but only over many dynamic times when averaged over a substantial volume of the disk. en
dc.language.iso en_US en
dc.publisher The American Astronomical Society en
dc.relation.isversionof https://doi.org/10.1088/0004-637X/746/1/98 en
dc.rights © 2012 The American Astronomical Society. All rights reserved. en
dc.subject accretion en
dc.subject accretion disks en
dc.subject protoplanetary disks en
dc.subject stars: formation en
dc.title Convergence studies of mass transport in disks with gravitational instabilities. I. the constant cooling time case en
dc.type Article en
dc.altmetrics.display false en


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