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Introduction and History

The variability of V1063 Cas (GSC 04493-01966) was discovered in Northern Sky Variability Survey (NSVS, Wozniak et al., 2004, IBVS 5700). They reported an ephemeris of Min. I = 2451578.75215 + 0.6200 d*E, and identified the variable as TYC 4493-1966-1, and gave its position, α=01h 04m 47.254s, β =+76˚ 06’ 13.59”. It is classified as an EW contact variable with a V magnitude range of 11.2-12.0.

The ASASSN information includes, alternate names: APASS_DR9ID 4936706, ALLWISE J010447.16+760613.5, GALEX J010447.2+760613, mean VMag 11.75, Amplitude VMag 0.54 , Ephemeris:

HJD= 2457940.05047d + 0.6200091*E (1)

J-K:0.422, B-V=0.798, parallax 1.9869 ± 0.0125 mas. distance (pc): 495 pc.

Their light curve is below:

The ASASSN-V J010447.11+760613.4 Light Curves (Pojmański 2002).

This system was observed as a part of our professional collaborative studies of interacting binaries between the Pisgah Astronomical Research Institute (PARI) and Appalachian State University (AppState), with data taken from AppState's Dark Sky Observatory (DSO) observations.

The observations were taken by Daniel Caton, Ronald Samec, and Danny Faulkner. Reduction and analyses was done by R. Samec.

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Period Determination

Four mean times (from BVRI data) of minimum light were calculated from our present observations, one primary and three secondary eclipses:

HJD I = 2457310.73361 ± 0.00078,

HJD II = 2457311.66319 ± 0.00160, 2457326.54313 ± 0.00108 and 2457337.70113 ± 0.00047. These minima were weighted as 1.0 in the period study.

In addition, four times of low light were calculated from ASAS data and were weighted 0.1. Also 6 timings were found in the literature (weighted 1.0 each).

These gave us a period study with an interval of 20.6 years. From these timings, two ephemerides have been calculated, a linear and a quadratic one:

JD Hel MinI = 2457326.54377±0.00042d + 0.62000902±0.00000013×E (1)

JD Hel MinI = 2457326.54275 ±0.00035d + 0.62000991±0.00000019×E+
0.000000000134±0.000000000024×E2 (2)

The O-C's of the linear and quadatic fits are listed in the table below:

The quadratic o-c plot is shown below:

The period study does shows an orbital period that is increasing as shown in he O-C curve. This might be due to mass transfer to the more massive, primary component making the mass ratio more extreme.

The quadratic ephemeris yields a 𝑃 ̇= 1.58^10-7 d/yr or a mass exchange rate of

in a conservative scenario (the primary component is the gainer).

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Light Curve Characteristics

The phased light curves below were calculated from equation (2):

The curves were of good precision, averaging about 1% photometric precision. The amplitude of the light curve varies from 0.58-0.61, I to B mags. The O'Connell effect, an indicator of spot activity was 0.001-0.006 mags, I to B, which is actually less than the error of the curves. The difference in minima, 0.02 to 0.06 B to I indicates over contact light curves in good thermal contact. The light curves do not attain the amplitude needed to display total eclipses.

The characteristics of the light curves are tabulated below:

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Light Curve Solution

Temperature

The 2MASS, J-K = 0.422 ± 0.049 for the binary star. These correspond to ~G8V±2. which yields a temperature of 5500±200 K. Fast rotating binary stars of this type are noted for having strong magnetic activity, so the binary is of solar type with a convective atmosphere.

Solution

The B,V,Rc and Ic curves were pre-modeled with Binary Maker 3.0 (Bradstreet and Steelman 2002). Fits were determined in all filter bands which were very stable. The solution was that of an over contact eclipsing binary. The parameters were then averaged (q=0.81, fill-out=0.13, i=85˚, T1=5500, T2=5507 with one 14˚ cool spot, T-FACT=1.2). (These were with an assumed third light.). These results were input into a 4-color simultaneous light curve calculation using the Wilson-Devinney Program (Wilson & Devinney 1971, Wilson 1990, 1994, Van Hamme and Wilson 1998). During the iterations, the third light went to negative values and was removed and the spot T-factor went to unity and so the spot was removed. The solution was computed in Mode 3 and converged to a solution. We also noted that R and I light curves appeared slightly deeper in the secondary so we redid the period study using a previous secondary for our starting minima. Convective parameters, g = 0.32, A = 0.5 were used.

A q-search was performed since the eclipses were not total. The more massive component is the slightly cooler one making the system a W-type W UMa contact binary (however, the component temperatures were nearly identical making this distinction less important). The Q-search solution is shown in the plot below:

Solution Parameters and Dimensions

Light Curve Solutions

Surface Geometry

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Observations

The 2015 BVRI light curves were taken on October 15-18, 20, and 31. and on November 11-13,14, 21, at Apalachian State University's Dark Sky Observatory, with the historical (installed 1981) 18” reflector, by Dan Caton, Ronald Samec, and Danny Faulkner, with a thermoelectrically cooled (-35 ºC) Apogee Alta U42 camera that had a 2048^2 E2V CCD and Bessell BVRcIc filters [Note: this CCD chip has since been recently repackged into a Finger Lakes Instrumentation Microline camera body]. It has a DFM FW-82 filter wheel with 8 positions, with 2” filters, Johnson-Cousins U, B, V, Rc, Ic, Luminance, clear, park (plug). Like the 32”, the camera and filter wheel are controlled with MaxIm DL.The 18” telescope is a former ground-based satellite tracking optical tube assembly, mounted on a German equatorial mount, and is controlled by the same DFM Engineering telescope control system as the DSO 32”.

Individual observations included 744 in B, 756 in V, and 673 in R, and 699 in I. The probable error of a single observation was 8 mmag in B, 9 mmag in V, 7 mmag in R, and 5 mmag in I. The nightly C-K values stayed constant throughout the observing run with a precision of less than 1%. Exposure times were 60s in B, 30s in V and 20s in R and 15s in I. To produce these images, nightly images were calibrated with 25 bias frames, at least five flat frames in each filter, and ten 300-second dark frames.

The finder chart and information for the comparison (C), check (K) stars are given below:

V1063 Cas finder Chart from JD 2457337

Some nightly light curves are shown below:

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Discussion, Conclusion, Future Work, and Acknowledgements

Discussion

V1063 Cas is an overcontact, W UMa binary. The fill-out was 33(1)% making it in firm contact. The system has a fairly extreme mass ratio of ~0.81 , and a component temperature difference of only ~16 K, so it is in good thermal contact. No spots were needed in the final modeling. The inclination of ~74 degrees gave no total eclipses. Its photometric spectral type indicates a surface temperature of ~5500 K for the components making it a solar type binary. Such a main sequence star would have a mass of ~0.94 Msun (G8V) and the secondary (from the mass ratio) would have a mass of ~0.76 Msun, making it somewhat undersized. These are very close to the calculated values (See the table of estimated absolute values above) The radii computed from Kepler‘s law and the contact binary characteristics (period and Roche lobe configuration, Binary Maker 3, Bradstreet and Steelman, 2002) yield an evolved system near the IV class which means V1063 Cas is very old (>10 Gyr). However, contact binaries are hard to characterize due to their component interactions.

Conclusion

The period of this binary indicates that it is increasing. This could be due to mass exchange with the flow toward the more massive component making the mass ratio more extreme.

Future Work

Radial velocity curves are needed to obtain absolute (not relative) system parameters.

Acknowledgments

We wish to think the physics and astronomy students from Appalachian State University that have helped with our many observing runs. We also thank the Lee Hawkins, the Observatory Engineer, for the maintenance of the Dark Sky Observtory.

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Abstract

CCD, BVRI light curves of V1063 Cas were taken on 15-18, 20, 31, October and 11-13, 14, 21 November 2015, at the Dark Sky Observatory, Appalachian State University with the historical (installed 1981) 18” reflector, by Dan Caton, Ronald Samec, and Danny Faulkner. The variability of V1063 Cas was discovered in Northern Sky Variability Survey (NSVS, Wozniak et al., 2004, IBVS 5700). They reported an ephemeris of Min. I = 2451578.75215 + 0.6200 d*E, and identified the variable as TYC 4493-1966-1, and gave its position, d=01h 04m 47.254s, a=+70˚ 06’ 13.59”. It is classified as an EW contact variable with a V magnitude range of 11.2-12.0. Four times of low light were found in ASAS observations. Six times of minimum light are found in the literature. Our present observations, included one primary BVRI eclipse and three secondary eclipses. From these data, we determined the following linear and quadratic ephemerides,

JD Hel MinI = 2457310.7335±0.0004d + 0.62000902±0.0000013×E (1) and

JD Hel MinI = 2457310.7325±0.0004d + 0.62000990±0.00000019×E +0.000000000134± 0.000000000024×E² (2).

Thus, from our 28.4-year period study, the orbital period is found to be increasing. This could be due to mass transfer making the mass ratio decrease (q=M2/M1). A Wilson-Devinney analyses reveals that the system is a W-type (less massive component is the hottest) W UMa binary with a fairly extreme mass ratio, q=0.8084±0.0007, 1/q=M1/M2=1.24). Its Roche Lobe fill-out is ~33%. No spot was needed in the solution. The temperature difference of the components is only ~16 K, with the more massive component as the slightly cooler one. The inclination is 73.7±0.1˚ so that no total eclipse was determined. A q-search was undertaken confirming the original solution. No third-light contribution or star spot was found. More information is given in this preliminary report.

JD Hel MinI = 2457310.7335±0.0004d + 0.62000902±0.0000013×E (1) and

JD Hel MinI = 2457310.7325±0.0004d + 0.62000990±0.00000019×E +0.000000000134± 0.000000000024×E² (2).

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Photometric BVRI Observations and the First Analyses of the Bright Solar Type Binary V1063 Cassiopeia

Daniel Caton (1), Ronald G. Samec (2), Danny Faulkner (3)

(1) Appalachian State University Dark Sky Observatory, (2) Pisgah Astronomical Research Institute, (3) Johnson Observatory

Introduction and History

Period Determination

Light Curve Characteristics