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  • Revisiting a gravity-darken...
    Kamiaka, Shoya; Masuda, Kento; Xue, Yuxin; Suto, Yasushi; Nishioka, Tsubasa; Murakami, Risa; Inayama, Koichiro; Saitoh, Madoka; Tanaka, Michisuke; Yonehara, Atsunori

    Publications of the Astronomical Society of Japan, 10/2015, Letnik: 67, Številka: 5
    Journal Article

    We reanalyse the time-variable light curves of the transiting planetary system PTFO 8-8695, in which a planet of 3 to 4 Jupiter masses orbits a rapidly rotating pre-main-sequence star. Both the planetary orbital period P orb of 0.448 d and the stellar spin period P s of less than 0.671 d are unusually short, which makes PTFO 8-8695 an ideal system to check the model of gravity darkening and nodal precession. While the previous analysis of PTFO 8-8695 assumed that the stellar spin and planetary orbital periods are the same, we extend the analysis by discarding the spin–orbit synchronous condition, and find three different classes of solutions roughly corresponding to the nodal precession periods of 199 ± 16, 475 ± 21, and 827 ± 53 d that reproduce the transit light curves observed in 2009 and 2010. We compare the predicted light curves of the three solutions against the photometry data of a few percent accuracy obtained at Koyama Astronomical Observatory in 2014 and 2015, and find that the solution with a precession period of 199 ± 16 d is preferred even though it is preliminary. Future prospects and implications for other transiting systems are briefly discussed.