Modeling Mid-Infrared Variability in Circumstellar Disks
First Author:
Kevin Flaherty
Email: kmf AT email.arizona.edu
University of AZ, Steward Observatory
933 N Cherry Ave
Tucson, AZ 85721 USA
Abstract
The Spitzer Space Telescope has opened up the possibility of obtaining time series mid-infrared observations of T-Tauri stars. A dedicated monitoring program of the young cluster IC 348 using Spitzer has found a number of stars, such as the G6 classical T-Tauri star LRLL 31, that exhibit unique and unexpected behavior. Based on IRS spectra of LRLL 31 separated by as little as a week we find that the short and long wavelength flux are anti-correlated with changes of the flux up to 30%. We present a series of simple models of this unusual variability. We consider a flat disk that is not confined to the midplane, either due to a warp at the outer edge, a warp at the inner edge or a spiral wave originating from the inner edge of the disk. These models show that the shadowing caused by a change in the height of the warp/spiral wave near the inner disk rim can reproduce the anti-correlation as well as the strength of the variability, while a precessing warp/spiral wave is unable to reproduce the observations.
