Accretion in the Disk of epsilon Aurigae: Results of Monte Carlo Radiative Transfer Modelling

Type Conference Paper
Names Naomi Pequette, R. Stencel, B. Whitney
Proceedings Title Bulletin of the American Astronomical Society
Conference Name American Astronomical Society, AAS Meeting #218, #225.05
Volume 43
Date May 1, 2011
Short Title Accretion in the Disk of epsilon Aurigae
Library Catalog NASA ADS
Abstract Epsilon Aurigae is a mysterious eclipsing binary system that has been observed for more than 175 years. Current theory remains undecided whether the system is made up of a massive F-supergiant star and an equally massive, but hidden, companion, or a post-AGB F-star and a binary companion made up of a B5V which is surrounded by a transitional or debris disk. We used a Monte Carlo Radiative Transfer Model (MCRTM, written by Barbra Whitney of the Space Sciences Institute) to model the B-star and surrounding disk. By using this model, our goal was to reproduce the observed Spectral Energy Distribution (SED, Hoard, Howell and Stencel, HHS, 2010) of the B-star and disk components of the epsilon Aurigae System. Our initial parameters utilized the results of HHS. The initial run of MCRTM did not result in matching the observed SED. Subsequently, we explored previously unknown disk parameters, most importantly disk mass and accretion rate. We found that to reproduce the observed 10:1 ratio of IR to Far-UV flux, we must have a non-zero rate of accretion occuring in the disk. To avoid depleting the disk too quickly, our simulations find that a more massive disk becomes too opaque due to increased scattering and does not reproduce the observed SED. Thus, we propose the extra mass might be in the form of planetesimals. The high accretion rate also implies dust mass replinishment, possibly due to a high rate of collisional interaction among planetesimals embedded in the disk. This work was supported in part by the bequest of William Herschel Womble in support of astronomy at the University of Denver, by NSF grant 1016678 and JPL RSA 1414715 to the University of Denver.
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