Vol 9, No 9 (2009) / Li

The ROSAT bright source 1RXS J201607.0+251645: an active Algol-type binary

Hua-Li Li, Yuan-Gui Yang, Wei Su, Hui-Juan Wang, Jian-Yan Wei


1RXS J201607.0+251645 is identified as an eclipsing binary. We present preliminary observations in the V band with the 0.6-m telescope for three years and extensive observations in the V and R bands with the 0.8-m telescope for six nights, respectively. The light curve of the system is EB type. Five light minimum times were obtained and the orbital period of 0.388058d(±0.00044d) is determined. The photometric solution given by the 2003-version of the Wilson-Devinney program suggests that the binary is a semidetached system with photometric mass ratio 0.895(±0.006), which is probably comprised of a G5 primary and an oversized K5 secondary. The less massive component has completely filled its Roche lobe, while the other one almost fills its Roche lobe with a filling factor of 93.4%. The system shows a varying O’Connell effect in its phase folded diagrams from 2005 to 2007, and is X-ray luminous with log LX/Lbol ∼ −3.27. Possible mechanisms to account for these two phenomena are discussed. Finally, we infer that the binary may be in thermal oscillation or may evolve into a contact binary.



stars: binaries: close — stars: binaries: eclipsing— stars: individual: 1RXS J201607.0+251645,HD 339946

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