CRTS J0552–0044: A young M3+M5 eclipsing binary in the 32 Ori Moving Group

Although M dwarfs comprise the overwhelming majority of stars in the Galaxy, a detailed understanding of these objects remains elusive. For example, current modelling struggles to accurately predict mass and radius in M dwarfs and this is especially true of pre-main sequence systems, where evolutionary models are poorly constrained observationally. Double-lined eclipsing binaries are key yardsticks for fundamental stellar parameters. However, due to the intrinsic faintness of such systems, there are currently only two dozen or so M+M eclipsing binaries that can be used to robustly test models and an even smaller number of pre-main sequence systems. We have recently identified and fully characterised a young (25 Myr), nearby (103 pc) 0.5+0.2 Msun eclipsing binary which is a member of the under-studied equatorial moving group 32 Orionis. At an age of 25 Myr and with component masses which straddle the fully-convective boundary for M dwarfs, the system is uniquely placed to test models of low-mass star formation, structure and evolution at intermediate epochs between the youngest star-forming regions such as Orion and the dispersed Gyr-old field population.