Dust and Gas Composition at the Inner Edge of the Transitional Disk Surrounding 7Myr old T Cha

The young (7 Myr) 1.5 solar mass T Tauri star T Cha shows dramatic variability due to optical extinction variations of up to 3 magnitudes on few hour time-scales with no obvious periodicity. We have conducted a major multi-spectral-region observing campaign to study the UV/X-ray/optical variability of T Cha. For 5 weeks (2018 Feb 9--Mar 17) we monitored the optical variability using LCOGT (Chile/South Africa/Australia) and SMARTS telescopes in Chile. We observed T Cha during 3 coordinated observations (each 5 HST orbits + 25 ksec XMM; on 2018 Feb 22, Feb 26, Mar 2) using HST COS/STIS to measure the FUV/NUV spectra and XMM-Newton to measure the corresponding X-ray spectra. The observed spectral changes are well correlated and demonstrate the influence of the same inner disk absorbing material in all the spectral regions observed. By examining which spectral features change and by how much we determine the location of different emitting regions relative to the absorbers along the line-of-sight to the star. In this talk we describe the dust and gas properties at T Cha's inner disk edge and show that the solid phase material consists almost entirely of very large grains/particles.