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We have observed and spatially resolved a set of seven A-type stars in thenearby Ursa Major moving group with the Classic, CLIMB, and PAVO beam combinerson the CHARA Array. At least four of these stars have large rotationalvelocities ($v \sin i$ $\gtrsim$ 170 $\mathrm{km~s^{-1}}$) and are expected tobe oblate. These interferometric measurements, the stars' observed photometricenergy distributions, and $v \sin i$ values are used to computationallyconstruct model oblate stars from which stellar properties (inclination,rotational velocity, and the radius and effective temperature as a function oflatitude, etc.) are determined. The results are compared with MESA stellarevolution models (Paxton et al. 2011, 2013) to determine masses and ages. Thevalue of this new technique is that it enables the estimation of thefundamental properties of rapidly rotating stars without the need to fullyimage the star. It can thus be applied to stars with sizes comparable to theinterferometric resolution limit as opposed to those that are several timeslarger than the limit. Under the assumption of coevality, the spread in agescan be used as a test of both the prescription presented here and the MESAevolutionary code for rapidly rotating stars. With our validated technique, wecombine these age estimates and determine the age of the moving group to be 414$\pm$ 23 Myr, which is consistent with, but much more precise than previousestimates.

The Ages of A-Stars I: Interferometric Observations and Age Estimates for Stars in the Ursa Major Moving Group