Accurate and precise effective temperature measurements for FGK stars with TESS

There is an urgent need for benchmark stars with direct and precise effective temperature measurements. Few standard stars currently available have effective temperature measurements that meet the required accuracy for calibrating temperature indicators for cool dwarf stars (+/- 50K or better). The recent availability of TESS light curves and Gaia parallaxes has made it possible to revisit the fundamental approach of deriving effective temperature for stars in eclipsing binaries (EBs). We present a new method that uses TESS light curves of EBs, Gaia parallaxes and multi-wavelength photometry to obtain very accurate fundamental effective temperatures. These measurements can be used to establish a set of benchmark stars for next-generation surveys. Initial results from the method include the F7V+K0IV binary AI Phoenicis, with T1 = 6199 +/- 22 K and T2 = 5094 +/- 16 K (Miller, Maxted & Smalley, 2020), and the newly identified system ASAS J051753-5406.0 (CPD-54 810), for which we present our preliminary results.