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Samec R.G.,Pisgah Astronomical Research Institute | Kring J.D.,Bob Jones University | Robb R.,University of Victoria | Van Hamme W.,Florida International University | Faulkner D.R.,University of South Carolina
Astronomical Journal | Year: 2015

GSC 3208 1986 is an NSVS and TYCHO binary, first observed from 1999 to 2000. It is a W UMa binary with a period of 0.405 days. The present observations were taken in 2012 September and are of high precision, averaging a standard deviation of better than 5 mmag. The amplitude of the light curve is very nearly 0.5 mag yet it undergoes total eclipses. Dominion Astrophysical Observatory spectra give an F3V type (T ∼ 6900 K) for the system, the earliest of the extreme mass ratio W UMa binaries. The linear period determination of 0.4045672 days was calculated with the two sets of epochs available. An early NSVS light curve reveals that the period has been smoothly decreasing over its past 12,000 orbits. The binary may be undergoing sinusoidal oscillations due to the presence of a third body, possibly with a period of 23 ± 3 years. The high inclination of 85° results in a long duration secondary total eclipse, lasting some 49.5 minutes. Findings indicate that GSC 3208 1986 is an immaculate extreme mass ratio, q(m2/m1) = 0.24, A-type W UMa binary. © 2015. The American Astronomical Society. All rights reserved. Source


Samec R.G.,Pisgah Astronomical Research Institute | Koenke S.S.,Bob Jones University | Faulkner D.R.,University of South Carolina
Astronomical Journal | Year: 2015

A 2012 follow up to the analysis of 2009 observations is presented for the very short period (∼0.43 days) precontact W UMa binary (PCWB) V1001 Cassiopeia. Its short period, similar to the majority of W UMa binaries, and its distinct EA light curve make it a very rare and interesting system for continuing photometric investigation. Previous photometric VRI standard magnitudes give a K4 spectral type. Our solutions of light curves separated by some three years give approximately the same physical parameters. However, the spots have radically changed in temperature, area, and position. While only one dark spot was used to model the first curves, two hot spots are now needed. This affects the overall shape of the light curve, especially in the secondary eclipses in B and V. Additional eclipse timings now show that the orbital period is changing. We conclude that spots are very active on this solar-type dwarf system and that it may mimic its larger cousins, the RS CVn binaries. The conclusion is that analysis now needs to be directed at the continuous time evolution of PCWBs. © 2015. The American Astronomical Society. All rights reserved.. Source


Samec R.G.,Pisgah Astronomical Research Institute | Samec R.G.,Emmanuel College at Franklin Springs | Benkendorf B.,Bob Jones University | Dignan J.B.,Bob Jones University | And 3 more authors.
Astronomical Journal | Year: 2015

HR Bootis is a neglected binary that is found to be a solar-type (G2V) extreme mass ratio binary (EMRB). It was discovered by Hanley & Shapley in 1940. Surprisingly, little has been published in the intervening years. In 1999 it was characterized by a 0.31587 day orbital period. Since that time it has been observed by various observers who have determined ∼20 timings of minimum light over the past ∼15,000 orbits. Our observations in 2012 represent the first precision curves in the BVRcIc Johnson-Cousins wavelength bands. The light curves have rather low amplitudes, averaging some 0.5 magnitudes, yet they exhibit total eclipses, which is typical of the rare group of solar-type EMRBs. An improved linear ephemeris was computed along with a quadratic ephemeris showing a decaying orbit, which indicates magnetic breaking may be occurring. The light curve solution reveals that HR Boo is a contact system with a somewhat low 21% Roche-lobe fill-out but a mass ratio of q = 4.09 (0.2444), which defines it as an EMRB. Two spots, both hot, were allowed to iterate to fit the light curve asymmetries. Their radii are 32and 16. Both are high-latitude polar spots indicative of strong magnetic activity. The shallow contact yet nearly equal component temperatures makes it an unusual addition to this group. © 2015. The American Astronomical Society. All rights reserved.. Source


Englert C.R.,U.S. Navy | Harlander J.M.,St. Cloud State University | Brown C.M.,U.S. Navy | Meriwether J.W.,Clemson University | And 5 more authors.
Journal of Atmospheric and Solar-Terrestrial Physics | Year: 2012

The thermospheric wind is a critical geophysical parameter for understanding the behavior of the Earth's upper atmosphere. Global-scale characterization of this parameter is needed to enable improved specification and forecasting of the near space environment. Global-scale measurements of horizontal wind vectors versus altitude have been performed from satellites using a variety of techniques, but the available data are still sparse. To address some of the challenges presented by space-based thermospheric wind measurement, the Doppler Asymmetric Spatial Heterodyne (DASH) technique has recently been developed. Here we present results of a ground-based validation of the DASH technique. The successful validation was performed by conducting collocated ground-based measurements with an instrument that uses the well established Fabry-Perot interferometer technique. Due to cloud cover and a limited observation period, data for only one night of simultaneous observations with minor cloud interference were obtained. The wind velocities observed by the two techniques show good overall agreement, but differences larger than the combined uncertainties are present at times. Contributions to these larger disagreements could be due to cloud interference, the minor differences in the observation geometry, or a non-zero vertical wind. A comparison of this single night of data with the Horizontal Wind Model (HWM07) climatology shows differences of up to about 100 m/s on timescales of less than an hour to several hours. © 2012. Source


Samec R.G.,Pisgah Astronomical Research Institute | Clark J.D.,Bob Jones University | Van Hamme W.,Florida International University | Faulkner D.R.,University of South Carolina
Astronomical Journal | Year: 2015

Complete Bessel BVRI light curves of ZZ Eridani [2MASS J04130109-1044545, HV 6280, NSVS 14888164 α(2000) = 04h13m1s10, δ(2000) = -10°44′54″.5 (ICRS), V = 13.9-14.4-15.0] are observed and analyzed. The system is a southern pre-contact W UMa binary. Its light curve has the appearance of an Algol (EA) light curve, however, it is made up of dwarf solar-type components with a period of only 0.4521 days. Our 34 year period study yields a sinusoidal fit or an increasing quadratic fit. The sinusoid may indicate that a third body is orbiting the close binary. The lower-limit mass of the third body is near that of the brown dwarf limit (0.095 M⊙). Also included is an improved ephemeris, a mass ratio search, and a simultaneous BVRI Wilson-Devinney solution. © 2015. The American Astronomical Society. All rights reserved. Source

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