Fundamental calibrators for stellar evolution models: New eclipsing binaries in young clusters identified by K2
Double-lined eclipsing binaries serve as fundamental calibrators for stellar evolution models. Benchmark grade calibrators (with mass and radius uncertainties of ~3%) having component masses below 1 solar mass are rare, particularly at pre-main sequence stages. We present the discovery and characterization of new eclipsing binaries in young stellar clusters, all identified by K2. In the 5-10 Myr old Upper Scorpius region, the nearest OB association, we present the lowest mass stellar eclipsing binary to date, with both components close to the hydrogen burning limit. Also in Upper Scorpius, we present evidence for a hierarchical triple with an eclipsing pair of brown dwarfs, only the second eclipsing brown dwarf pair known to date. In the 110-125 Myr old Pleiades cluster, only one eclipsing binary was known prior to the K2 mission. We present three new Pleiades eclipsing binaries, all with system masses less than 1 solar mass. We use these systems to critically assess stellar evolution models at low masses and young ages. K2 data in hand has also revealed new eclipsing and transiting systems in the moderately older (600-800 Myr) Hyades and Praesepe clusters.