Presentation #205.18 in the session Binary Stellar System - iPoster Session.
CCD, BVRI light curves of V471 Cas were taken on 8, 9, and 10, November 2020, remotely, at the SARA Jacobus Kapteyn 1.0-m Telescope (JKT), La Palma, Canary Islands, Spain by Ronald Samec and Walter Van Hamme. The variability of V471 Cas (2MASS J01322047+5512196) was discovered by Hoffmeister (1966). It is classified as an EW binary by Liu & Huisong (1991,1993) with a period of 0.405356 d. and a B-V=0.77±0.02. Their solution gave a mass ratio of 0.6. Kjurkchieva, et al. 2019 published i’, g’ curves and published a solution using a search algorithm. Neither of the papers used a third light in the solution. Five times of minimum light were determined from our present observations, which include three primary and two secondary eclipses. Caton added fourteen new timings. From sixty-five recent low scatter minima, including many from the literature, we determined an ephemeris with a 17 σ positive quadratic term.
In an 82-year period study, the later, low scatter, linear residuals form a sinusoidal curve. An analysis by Wolf, yields a composite third body of mass 0.11 Msolar. The sinusoidal ephemeris follows: JD Hel MinI = 2459141.53622(21)d+ 0.400937799(12)×E+3.5(2)×10-11×E2+ 0.01271(0.000766) SIN[0.001563(70)×E+1.06(390)]. The quadratic ephemeris is JD Hel MinI=2459141.53690(12)d + 0.40093781(4)×E +0.000000000035(2)×E2
A Wilson-Devinney analysis reveals that the system is a A-type W UMa binary with a mass ratio near unity, q=0.893±0.007 (star 1 is the more massive, primary component). Its Roche Lobe fill-out is low, ~8%. One hot spot was needed in the solution. The temperature difference of the components is only ~30 K. The inclination is not quite high enough, 82.33±0.03˚ to yield a total eclipse. The third light gives a V normalized light value of 0.0366 at phase 0.5. Despite the inclusion of third light, the eclipses are not total, so the light curve solution is still ambiguous. More information is given in this preliminary report.