Observational Study of the 0.9d Period, Solar-Type, Totally Eclipsing, Near-Contact Eclipsing Binary, NS Camelopardalis

CCD, BVRI light curves of NS Cam were taken on 1, 20, 21, 22, and 23 January, and 4, 22, and 23 February 2020 at the Dark Sky Observatory, North Carolina with the 0.81-m reflector of Appalachian State University by Daniel Caton, Danny Faulkner and Ronald Samec. The initial study (light curves, classification, ephemeris etc.) of NS Cam (NSV 3771, GSC 4373 0708) was given by Khruslov and Tula of the SKYdot team (IBVS 5699). They classified it as an EB system with a maximum magnitude of 12.9 and minima of 13.5 and 13.2 for the primary and secondary eclipses. The period was 0.90733 d. Three times of minimum light were determined form our present observations, which include one primary eclipse and two secondary eclipses: HJD I = 2457849.5230 ± 0.0011 d, HJD II = 2457870.8428 ± 0.0016 and 2457883.54736 ± 0.00068 d. We selected 4 times of low light from parabola fits of ASAS SN observations. From these we determined both linear and quadratic ephemerides, JD Hel Min I = (2457883.587 ± 0.013 + (0.9072950 ± 0.0000043)×E) d (1), JD Hel Min I = (2457883.5517 ± 0.0063 + (0.9072416 ± 0.000052)×E - (0.0000000080 ± 0.0000000007)×E²) d (2). Thus from our 17.5 year study, the period is found to be decreasing. Since the spectral types are ~G3V, this is probably due to magnetic braking. Wilson-Devinney analyses reveal that the system is a detached, near contact binary in nearly a classical Algol configuration. The component temperature difference is 535 K. The mass ratio is somewhat extreme, M2/M1 = 0.2143 ± 0.003. The total eclipses make this a firm determination. Its Roche Lobe fill-outs are identical (~99.5%), within the errors of the potentials. The dark spot was at midlatitude (colatitude = 62°), with a radius of ~20° and a Tfactor of only ~0.4. The spot was on the primary component, facing the secondary component (system gravitationally locked). The inclination is high, at 82.6 ± 0.2 deg, resulting in a total eclipse. As a result, the primary minimum has a time of constant light with an eclipse duration of 91.5 minutes. More information is given in this preliminary report.