JWST Captures a Sudden Stellar Outburst and Inner Disk Wall Destruction

We analyze JWST/MIRI observations of T Cha, a highly variable (ΔV ∼ 3–5 mag) accreting Sun-like star surrounded by a disk with a large (∼15 au) dust gap. We find that the JWST mid-IR spectrum is significantly different from the Spitzer spectrum obtained 17 yr before—the emission at short wavelengths (5–10 μm) has decreased by ∼2/3 while that at longer wavelengths (15–25 μm) has increased by up to a factor of ∼3. The JWST spectrum is contemporaneous with a fairly constant higher optical emission captured by the All Sky Automated Survey. After analyzing and modeling both spectral energy distributions, we propose that JWST caught the star during an outburst that partly destroyed and significantly reduced the height of the asymmetric inner disk wall responsible for the high optical variability and lower 15–25 μm emission during the Spitzer period. The dust mass lost during this outburst is estimated to be comparable (∼1/5) to the upper limit of the total micron-sized dust mass in the inner disk of T Cha now. Monitoring this system during possible future outbursts and more observations of its quiescent state will reveal if the inner disk can be replenished or will continue to be depleted and vanish.