Revisiting a gravity-darkened and precessing planetary system PTFO 8-8695: spin-orbit non-synchronous case

Abstract

We reanalyse the time-variable lightcurves of the transiting planetary system PTFO 8-8695, in which a planet of 3 to 4 Jupiter mass orbits around a rapidly rotating pre-main-sequence star. Both the planetary orbital period of 0.448 days and the stellar spin period less than 0.671 days 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$\pm$16, 475$\pm$21, and 827$\pm$53 days that reproduce the transit lightcurves observed in 2009 and 2010. We compare the predicted lightcurves of the three solutions against the photometry data of a few percent accuracy obtained at Koyama Astronomical Observatory in 2014 and 2015, and find that the solution with the precession period of 199$\pm$16 days is preferred even though preliminary. Future prospect and implications to other transiting systems are briefly discussed.

9 pages, 6 Figures, 2 Tables, accepted for publication in PASJ

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Cited by in corpus (8)

• YETI observations of the young transiting planet candidate CVSO 30 b
• Multi-Color Simultaneous Photometry of the T-Tauri Star Having A Planetary Candidate CVSO 30
• A reappraisal of parameters for the putative planet PTFO 8-8695b and its potentially precessing parent star
• Direct Imaging discovery of a second planet candidate around the possibly transiting planet host CVSO 30
• Evidence for planetary hypothesis for PTFO 8-8695b with five-year optical/infrared monitoring observations
• X-ray emission in the enigmatic CVSO 30 system
• A Wide-Field Survey for Transiting Hot Jupiters and Eclipsing Pre-Main-Sequence Binaries in Young Stellar Associations
• PTFO 8-8695: Two Stars, Two Signals, No Planet