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Analyses and Period Study of the Totally Eclipsing, Southern Solar Type Binary, SZ Sculptoris

Published onJun 01, 2020
Analyses and Period Study of the Totally Eclipsing, Southern Solar Type Binary, SZ Sculptoris

We report here on a BVRcIc observations, analysis and period study of SZ Scl (GSC 6990-0597), a solar type (T ~ 5040 K), shallow contact, eclipsing binary. It was observed on 05, 07, and 15, October 2019 in remote mode on the Cerro Tololo InterAmerican Observatory, 0.6-m SARA South reflector by R.Samec. The amplitude of the light curves was 0.68 mags in V. Six times of minimum light were calculated from both three primary eclipses and three secondary eclipses, from our present observations: HJD I = 2458771.75786 ± 0.00029, 2458792.61086 ± 0.00010, 2458794.53585 ± 0.00021 d, HJD II = 2458771.59807 ± 0.00094, 2458792.77217 ± 0.00084, 2458794.69767 ± 0.00079 d. Eight times of low light were also taken from ASAS SN observations. Two additional timings were taken from the BBSAG bulletin #39. From 13 years of observations, the orbital period was found to be decreasing over this interval: JD Hel Min I = (2458792.61140(34) + 0.32081788(25)×E - 0.000000000225(6)×E2) d. This may be due to angular momentum loss (AML) resulting from rotating ion streams leaving along stiff magnetic bipolar field lines from the system. A linear ephemeris was also calculated: JD Hel Min I = (2458792.6156(25) + 0.32082842(15)×E) d. A Wilson-Devinney Program (W-D) solution of BVRcIc Johnson-Cousins filtered observations gives a mass ratio of m1/m2 = 0.3800 ± 0.0007, and a substantial component temperature difference of 350 K and a contact fill-out of only 11%. Thus, the system is in poor thermal contact. A near equatorial spot (colatitude of 112.5 ± 0.5 deg), radius of 15.04 ± 0.45 deg and T-factor of 0.84 ± 0.01 were calculated. The system is an unusual shallow contact A-type W UMa Binary (pshift = 0.5), albeit, the depths of the primary and secondary eclipse are equal within the errors. An eclipse duration of ~21 minutes was determined for the secondary eclipse and the light curve solution. Additional and more detailed information is given in the poster paper.

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