The Age of the KIC 7177553 System

KIC 7177553 is a quadruple system containing two binaries of orbital periods 16.5 and 18 d. All components have comparable masses and are slowly rotating, non-evolved stars of spectral type near G2V. The longer period binary is eclipsing with component masses and radii, M1 = 1.043 +/- 0.014 M_sun, R1 = 0.940 +/- 0.005 R_sun, and M2 = 0.986 +/- 0.015 M_sun, R2 = 0.941 +/- 0.005 R_sun. The essentially equal radii measurements are inconsistent with the two stars being on the main sequence at the same age using standard stellar evolution models. Instead a consistent scenario is found if the stars are in their pre-main sequence phase of evolution and have age 33 - 36 Myr. Such a young age has important implications for the detectability of the massive planet indicated by eclipse time variations.