Absence of a thick atmosphere on a terrestrial exoplanet

I will present a thermal phase curve measurement for a terrestrial exoplanet recently detected by the TESS mission. The planet is in a short period orbit around a nearby M-dwarf star. The phase curve is the first such measurement for a planet smaller than 1.6 Earth radii, the size below which the existence of an atmosphere is unknown a priori. The amplitude of the phase variation puts strong constraints on the planet's atmospheric properties, which I will discuss.