Photometric Observations of the Totally Eclipsing, Solar Type Eclipsing Binary, DK Andromedae

We present the first precision BVRI light curves, synthetic light curve solutions and a period study for the Sonneberg variable, DK And. Observations were taken with the NURO 0.81-m Lowell reflector on 24, 25 and 27 September and 26 October and 01 November 2011 with the SARA 0.9-m reflector. Our light curves were premodeled with Binary Maker 3.0, and solved with the Wilson-Devinney program. Our observations included 374 B, 372 V, 392 R and 394 I individual and calibrated observations. These were taken with the NURO, Lowell 2KX2K NASACAM, and the SARA 1KX1K Apogee camera. Six mean times of minimum light were determined, includingHJDMin I= 2455866.8222(±0.0003), 2455828.6632(±0.0001), 2455829.6405(±0.0097), and HJDMin II=2455866.5782(±0.0007), 2455860.6970(±0.0053) and 2455828.9081(±0.0004). Thirty-one timings taken over 73 years are included in our ephemeris calculation: J.D. Hel Min I = 2451435.4330(±0.0011)d + 0.48922346(±0.00000015)×E + 2.4(±0.4)×10_-11×E₂ For conservative mass transfer, the positive quadratic term means that the more massive star is the gainer. Our light curves shows a time of constant light in the secondary eclipse of 28 minutes making this an A-type W UMa system. The amplitude of the light curves are about 0.5 mags in V. The light curve solution reveals a rather extreme mass ratio of 0.32, a component temperature difference of ~300K, and an inclination of 82.5°. The curves show the effects of dark spot activity. We thank USC, Lancaster for their support of our membership in NURO for the past 8 years, the American Astronomical Society for its support through its small research program and Arizona Space grant for the partial support for our student’s travel.