Presentation #215.01 in the session “Binary Stellar Systems I”.
CCD, BVRI light curves of V1115 CAS were taken on 8, 9, and 10, November 2020, remotely, at the SARA Jacobus Kapteyn 1.0-m Telescope , La Palma, Canary Islands, Spain. Further observations were made in October 2020 at Dark Sky Observatory. The variability of V1115Cas (2MASS J01322075+5513569) was discovered by Hoffmeister (1966). It is classified as a contact variable with a mean V magnitude of 14.32, an amplitude of V=0.532 mags and a period of 0.32328248d. Four times of minimum light were determined from our present observations, which include two primary and two secondary eclipses. We selected 8 times of low light from ASAS SN observations and 48 timings from the literature. From these we determined the following linear ephemeris, JD Hel MinI = 24558870.5185(17)d + 0.32328248(15)×E (1). In the 19 year period study, the residuals form a sinusoidal curve. An analysis of this curve yields a third body of mass 0.23 solar masses. A Wilson-Devinney analysis reveals that the system is an W-type W UMa binary with a somewhat extreme mass ratio, q = 0.2296 ± 0.0002 (star 1 is the more massive, primary component, 1/q = M1/M2 = 4.4). Its Roche Lobe fill-out is ~24%. Two spots were needed in the solution. The temperature difference of the components is ~225 K, with the more massive component as the slightly cooler one, so that in the present observations, it is an W-type W UMa Binary. The inclination is high, 86.06 ± 0.13° resulting in a total eclipse. As a result, the secondary minimum has a time of constant light with an eclipse duration of some 37 minutes. More information is given in this preliminary report.