Optical Flares and Quasi-Periodic Pulsations (QPPs) on CR Draconis during Periastron Passage

Volume 46 number 1 (2018)

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Gary Vander Haagen

Stonegate Observatory, 825 Stonegate Road, Ann Arbor, MI; garyvh2@gmail.com

Abstract

The high cadence search at a primary sampling rate of 10 samples/sec of CR Dra revealed six B-band flares totaling 7,574 seconds duration at 26 to 62 mmag peak above the mean. The search for sub-second or spike flares was also conducted with negative results. The study collected 2.5 × 106 photometric measurements over 69.36 hours from 6 July through 10 October 2017. This represents a flare rate of 0.086 flare/hour. The analysis confirmed detection of quasi-periodic pulsations (QPPs) at periods of 71, 51, 39.5–40.9, 32, 28.4, and 21.3–21.7 seconds in the 2017-10-10 flare data within the impulsive and decay phases. Published B-band flare data from 1970–2017 over the binary’s two-body separation of 2.96–2.1 AU and through periastron passage were tabulated and analyzed using chi square. The analysis confirmed that there is statistical significance for flaring at periastron verses the more distant separations at better than a 95% probability level. This conclusion should be confirmed with a second more homogeneous photometric study over a similar range of linear two-body separations.