AAVSO: American Association of Variable Star Observers

Observations and Analysis of the Extreme Mass Ratio, High Fill-out Solar Type Binary, V1695 Aquilae

Volume 45 number 2 (2017)

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Ronald G. Samec
Natural Sciences Dept. Emmanuel College,181 Springs Street, Franklin Springs, GA 30639; ronaldsamec@gmail.com
Christopher R. Gray
Natural Sciences Dept. Emmanuel College,181 Springs Street, Franklin Springs, GA 30639
Daniel Caton
Dark Sky Observatory, Department of Physics and Astronomy, Appalachian State University, 525 Rivers Street, Boone, NC 28608
Danny R. Faulkner
Johnson Observatory, 1414 Bur Oak ourt., Hebron, KY 41048
Robert Hill
Robert Hill Department of Chemistry and Physics, Bob Jones University, 1700 Wade Hampton Blvd., Greenville, SC 29614
Walter Van Hamme
Department of Physics, Florida International University,11200 SW 8th Street, CP 204, Miami, FL 33199


CCD BVRcIc light curves of V1695 Aquilae were taken during the Fall 2016 season at the Cerro Tololo InterAmerican Observatory with the 0.6-meter reflector of the SARA South observatory in remote mode. It is an eclipsing binary with a period of 0.41283 d. The light curves yield a total eclipse (duration: 59 minutes) but have an amplitude of only ~0.4 mag. The spectral type is ~G8V (~5500 K). Four times of minimum light were calculated, all primary eclipses, from our present observations. We calculated linear and quadratic ephemerides from all available times of minimum light. A 17-year period study reveals a quadratic orbital period decrease at a high level of confidence. The orbital period is changing at a rapid rate of of dp / dt = –1.73 × 10–6 d/yr. The solution is that of an Extreme Mass Ratio Binary. The mass ratio is found to be near 0.16. Its Roche Lobe fill-out is a hefty 83%. The small component has the slightly hotter temperature of ~5650 K, which makes it a W-type W UMa Binary. As expected in binaries of this spectral type, it has cool spot regions.