Convergence studies of mass transport in disks with gravitational instabilities. I. the constant cooling time case
dc.altmetrics.display | false | en |
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.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.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 | https://hdl.handle.net/2022/19066 | |
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 |
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