JWST captures a sudden stellar outburst and inner disk wall destruction

We present JWST/MIRI observations of T~Cha, a highly variable ($\mathrm{\Delta }V\sim$3-5,mag) accreting Sun-like star surrounded by a disk with a large ($\sim 15$,au) dust gap. We find that the JWST mid-infrared spectrum is signiticantly different from the {\it Spitzer} spectrum obtained 17 years before, where the emission at short wavelengths ($5-10\mu m$) has decreased by $\sim 2\mathrm{/}3$ while at longer wavelengths ($15-25\mu m$) it increased by up to a factor of $\sim 3$. This ‘seesaw’ behavior is contemporary with a fairly constant higher optical emission captured by the All Sky Automated Survey. By analyzing and modelling both SEDs, we propose that JWST caught the star during an outburst that destructed the asymmetric inner disk wall responsible for the high optical variability and lower $15-25$,micron\ emission during the {\it Spitzer} time. The dust mass lost during this outburst is estimated to be comparable ($\sim 1\mathrm{/}5$) 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.