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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 448223.0, MPI für Astronomie / Publikationen_mpia
Radiative transfer in very optically thick circumstellar disks
Authors:Min, M.; Dullemond, C. P.; Dominik, C.; de Koter, A.; Hovenier, J. W.
Date of Publication (YYYY-MM-DD):2009
Title of Journal:Astronomy and Astrophysics
Journal Abbrev.:A & A
Start Page:155
End Page:166
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:Aims. In this paper we present two efficient implementations of the diffusion approximation to be employed in Monte Carlo computations of radiative transfer in dusty media of massive circumstellar disks. The aim is to improve the accuracy of the computed temperature structure and to decrease the computation time. The accuracy, efficiency, and applicability of the methods in various corners of parameter space are investigated. The effects of using these methods on the vertical structure of the circumstellar disk as obtained from hydrostatic equilibrium computations are also addressed. Methods: Two methods are presented. First, an energy diffusion approximation is used to improve the accuracy of the temperature structure in highly obscured regions of the disk, where photon counts are low. Second, a modified random walk approximation is employed to decrease the computation time. This modified random walk ensures that the photons that end up in the high-density regions can quickly escape to the lower density regions, while the energy deposited by these photons in the disk is still computed accurately. A new radiative transfer code, MCMax, is presented in which both these diffusion approximations are implemented. These can be used simultaneously to increase both computational speed and decrease statistical noise. Results: We conclude that the diffusion approximations allow for fast and accurate computations of the temperature structure, vertical disk structure and observables of very optically thick circumstellar disks.
Free Keywords:radiative transfer; diffusion; stars: circumstellar matter
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:URL:http://adsabs.harvard.edu/abs/2009A%26A...497..155... [ID No:1]
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