Danny R. Faulkner

CN Andromedae: A Broken-Contact Binary?

We solve new UBV light curves of the eclipsing binary CN Andromedae simultaneously with radial velocities by the method of differential corrections. We find it semidetached with the more massive star filling its limiting lobe and the less massive star very close to lobe-filling. Our solutions of earlier light curves have the same configuration. Within the uncertainties, the system may be in a broken or a marginal contact stage as it undergoes thermal relaxation oscillations. The light curves are strongly affected by a large dark spot at high latitude on the more massive star and by a bright substellar spot on the companion. Spot locations and temperatures do not differ significantly from epoch to epoch. Based on single star evolutionary models, the primarys mass (1.299 ± 0.045 M⊙) and radius (1.425 ± 0.016 R⊙) are consistent with those of a star of age 2.9 × 109 yr that will leave the main sequence in another 2.0 × 109 yr. The orbital period has decreased during the past 50 yr according to traditional eclipse timings and also according to our generalized light and velocity solutions that include a reference epoch T0 and a rate of period change dP/dt. We find dP/dt = -0.01951 ± 0.00054 s yr-1, which is consistent with mass transfer from the more to the less massive star of 1.4 × 10-7 M⊙ yr-1, assuming no mass is lost from the system. Reliable absolute dimensions are determined.

Epochs of minimum light for 27 eclipsing binaries

Sixty-one epochs of minimum light for 27 eclipsing binaries are presented. Where possible these epochs are compared to existing and reliable light elements. Improved light elements have been computed for WZ And, V417 Aql, ZZ Aur, AP Aur, ACCMi, AX Dra, and XZ Leo. Brief notes are made on the periods of SS Ari, AP Aur, U Cep, and GR Tau. The first photoelectric light curves of WZ And and TY Del have been obtained, for which solutions will be forthcoming. TZ Dra is identified as being a BD star, while it is pointed out that FR Vul is probably not a BD star.

THE PHYSICAL NATURE AND ORBITAL BEHAVIOR OF V523 CASSIOPEIAE

V523 Cassiopeiae is a dwarf contact binary with one of the shortest orbital periods among the nondegenerate systems. Its orbital history is marked by large period changes. The photometrically determined mass ratios have historically been inconsistent with those calculated from radial velocity curves. In 1998 we acquired high-precision and standardized Johnson-Cousins UBV light curves. Our simultaneous BV light curve/radial velocity curve solutions provided good fits to both the light curves and the radial velocity curves using standard gravity darkening coefficients with a mass ratio of ~0.5. Seven precision mean epochs of minimum light were determined from these observations. We combine these with all available published times of minimum light, along with 50 times of low light found from a search of the archival Harvard plate stacks in the interval 1901–1942 to give us 567 eclipse timings. Our period study covers nearly 160,000 orbits, or ~102 yr. We find a high-amplitude sinusoidal variation with a period of 101 ± 7 yr, overlaid on a strong continuous period increase. The quadratic term is common in contact binaries, but a sinusoidal one is not. This suggests a hierarchical three-star system. Assuming that this is the case and that the inclination from our orbital solution for the close pair is the same as the larger orbit, we obtain a mass for the third star of 0.41 M⊙. This is similar to the masses of the stars that comprise the contact binary. If this scenario is correct, V523 Cas consists of a trio of late K and early M-type dwarfs having a total mass of ~1.6 M⊙. We show that high-resolution imaging can confirm this suggestion.

RR Leporis - An Algol-like system

The eclipsing binary star RR Lep was observed on seven nights during December 1979 with the facilities at Cerro Tololo Inter-American Observatory. The observations covering eclipse portions of the light curve yielded two epochs of minimum light. These observations are apparently the first published photoelectric data to be reported on the system. A study of the period of the system indicates that it may have remained fairly constant for almost 50 years. The light curves, defined by 700 observations with the B filter and 699 with the V filter, indicate a very large temperature disparity between the components and they show a superluminous region between the phases of 0.1 and 0.26. Also, a sinusoidal light variation is found to be present in the light curve over half a cycle. The light curves are modeled with the Wilson-Devinney code. The preliminary solution indicates that RR Lep is a classical semidetached Algol system with an A-type primary and a K-type secondary which fills its Roche lobe.

BVRI PHOTOMETRIC 2015 WD ANALYSIS OF THE SOUTHERN TOTALLY ECLIPSING, SOLAR-TYPE, SHALLOW-CONTACT W UMA BINARY, DD INDUS

Observations and a 2015 Wilson–Devinney Program analysis are undertaken for the first precision observations of DD Indi. DD Indi is of solar-type (T 1 ~ 5750 K) and was determined to be a shallow-contact eclipsing binary. It was observed from 2013 June through September at Cerro Tololo InterAmerican Observatory in remote mode. The 24 inch Boller and Chivens reflector, now under management by The Southeastern Association for Resarch in Astronomomy (SARA) was used. Five new eclipse timings were obtained, for three primary and two secondary eclipses. Seven more eclipse timings were calculated from All Sky Automated Survey data. A possibly increasing period was found from all available eclipse timings with a 5 ± 2 × 10−11 × E 2 quadratic term. A BVR c I c simultaneous synthetic light-curve analysis reveals that the system has a mass ratio of ~0.46, a ~ 140 K component temperature difference, and two weak cool spots. The Roche Lobe fill-out of this W-type binary is only ~11%, and an inclination of ~86° was determined. A time of constant light of ~16 minutes is measured around phase zero. More detail is included in this report.

IS NSVS 5066754 A NEAR-CONTACT OR A MARGINAL CONTACT BINARY?

BVR c I c light curves of NSVS 5066754 were taken on 2014 May at Dark Sky Observatory in North Carolina. This variable is a solar-type eclipsing binary (T1 ~ 5750 K) with a period of only 0.3751689(1) days. It appeared to be one of the shortest periods in Shaws list of near-contact binaries. The Binary Maker fits and our Wilson–Devinney solutions show that the binary could have both semidetached and marginal contact binary configurations. Five new times of minimum light were calculated, along with two minima determined from archived All Sky Automated Survey observations. From these minima and the discovery epoch, a quadratic ephemeris was determined. Thus, a magnetic braking scenario is possible. Both semidetached and contact models were explored. A marginal contact solution had the best sum of square residuals. It gave a mass ratio of ~0.5, and a component temperature difference of ~360 K, albeit somewhat large for a contact binary. Two substantial cool spots were determined in this solution with 37° and 28° radii and t-factors or 0.94 and 0.78 respectively. The fill-out is very shallow, ~106%. It may have recently achieved contact.

BVRcIc Observations and Analysis of the Near-Contact Solar Type Eclipsing Binary, V530 Andromedae

We present the first precision UBVRcIc light curves, an initial period study, and a simultaneous light curve solution for the near-contact solar type eclipsing binary V530 And. Our observations were taken with the 0.81 m Lowell reflector on 27 and 29 September, 2011, with time being granted from the National Undergraduate Research Observatory (NURO). Our Wilson Devinney Program solution yields a semidetached, V1010 Oph configuration: the more massive component is filling its Roche lobe. The system is apparently approaching contact for the first time. It is not a classic Algol.

UBVRI Photometric Analysis of the Solar-Type Eclipsing Binary TYC 3034-299-1

TYC 3034-0299-1 (CVn) is a magnetically active, contact binary, ROTSE variable. UBVRcIc light curves are presented along with a period study and a simultaneous UBVRI light curve solution. Our light curves show eclipse amplitudes of 0.72 and 0.62 mags (V) in the primary and secondary eclipses. Modeled results include a dark spot region, found at longitude 51°, a 24% Roche lobe fill-out, and a mass ratio of 0.48. A total eclipse is found to occur in the secondary eclipse making TYC 3034-0299-1 a W-type (less massive star is hotter) W UMa variable.