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The Remarkable Spectroscopic and Photometric Variability of T Cha

We report on the ground-based data from a coordinated multiwavelength observing campaign on the highly-variable pre-main sequence star T Cha. The T Cha system is viewed nearly edge-on; much of the variability is likely caused by obscuration by the inner disk. The goal of the campaign is to study the structure of the gas and dust in the inner protoplanetary disk. The campaign was organized around three visits from XMM and the HST, which are reported elsewhere. Here we report on optical spectroscopy and optical and near-IR photometry. The photometry reveals periodicities at either 3.3 or 6.4 days. The color- magnitude diagrams suggest extinction with A V > 5 . We took spectra at 10-30 minute time resolution on the 8 nights of the campaign, including a 7.5 hour continuous sequence simultaneous with the third HST/XMM visit. The equivalent width of the H α line varies from -8.5Å (net emission) to +2.2Å (net absorption). We discuss the implications of the photometry and the variability of the H α line profile.