Optical Variability of the T Tauri Star HH 30 IRS

Abstract

We report results of VRI photometric monitoring of the T Tauri star plus disk system HH 30 IRS. We find that HH 30 IRS is highly variable over timescales of a few days with ΔV ~ 1.5 mag, ΔI ~ 1.1 mag. Furthermore, we find hints of periodicity with periodograms indicating possible periods of 11.6 and 19.8 days. The VRI photometry is available through the ANONYMOUS FTP service. We model the variability with Monte Carlo radiation transfer simulations for a spotted star plus disk system and find that the large variability is best reproduced with a single hot spot and circumstellar grains that are larger than typical interstellar grains. The apparent existence of a single hot spot and the need for larger, more forward-throwing grains is consistent with previous modeling of Hubble Space Telescope imagery.