Analysis of CHEOPS light curves for eclipsing binaries with very low mass stars

CHEOPS is an ESA S-class mission that was launched in December 2019. It is the first mission dedicated to searching for exoplanetary transits by performing ultrahigh precision photometry on bright stars already known to host planets. 80% of the time on CHEOPS ( ~17500 orbits) is allocated for Guaranteed Time Observations, including ~500 orbits assigned to observe about 30 eclipsing binaries with very low mass companions. Solar-type stars with transiting M-dwarf companions are found in large numbers by surveys for transiting exoplanets. These "EBLM" (eclipsing binary, low-mass) systems are ideal for calibrating the mass-radius-metallicity relation for very low mass stars using the same techniques employed for transiting exoplanets. This relation is very poorly defined currently, and it has become urgent to improve it since it has become clear that low mass stars host more rocky planets in the habitable zone than more massive stars, and it is much easier to study these planets in detail.