THE AGE OF THE KIC 7177553 SYSTEM

KIC 7177553 is a quadruple system containing two binaries of orbital periods 16.5 and 18 days. All components have comparable masses and are slowly rotating with spectral types of ∼G2V. The longer period binary is eclipsing with component masses and radii M ₁ = 1.043 ± 0.014 M _⊙, R ₁ = 0.940 ± 0.005 R _⊙ and M ₂ = 0.986 ± 0.015 M _⊙, R ₂ = 0.941 ± 0.005 R _⊙. The essentially equal radii measurements are inconsistent with the two stars being on the man sequence at the same age using standard nonmagnetic stellar evolution models. Instead a consistent scenario is found if the stars are in their pre-main-sequence phase of evolution and have an age of 32–36 Myr. We have also computed evolutionary models of magnetic stars, but we find that our nonmagnetic models fit the empirical radii and effective temperatures better than the magnetic models.