A Study of the Kepler K2 Variable EPIC 211957146 Exhibiting a Variable O’ Connell Effect
- Department of Astronomy, Osmania University, Hyderabad 500007 (India)
We present the multi-band photometric and spectroscopic study of an over-contact binary system, EPIC 211957146. The light curves exhibit a variable O’ Connell effect, confirmed from our observational data and the Kepler K2 data. The best photometric solution incorporating a dark spot over the primary component unveils that the system has a low-mass ratio ( q ∼ 0.17) and a high inclination ( i ∼ 85°). To confirm the solution and constrain the uncertainty, Monte-Carlo simulations are performed and the results are reported. Based on the O–C diagram analysis, we see that the variable shows a period increase at the rate of dP / dt ∼ 1.06 × 10{sup −6} days yr{sup −1}, which is higher than the theoretically predicted value. Presence of a third body having a period of ∼16.23 years is evident from the O–C diagram. No filled-in effect is observed in the H α line, while the effect is vividly present in the Na line. From the Kepler K2 data, we found that the primary and secondary minima exhibit an anti-correlated O–C variation followed by an erratic behavior. This is possibly caused by the longitudinal motion of the spot, and hence, we set a lower limit of ∼40 days for the spot modulation. We also observe a possibly associated photometric difference in the primary depth by comparing our light curves with Kepler K2 normalized light curves. This system has a low-mass ratio and a high fill-out factor, and, theoretically, such a physical configuration would lead to a merger.
- OSTI ID:
- 22663682
- Journal Information:
- Astronomical Journal (Online), Vol. 153, Issue 5; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1538-3881
- Country of Publication:
- United States
- Language:
- English
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