Predicting a Third Planet in the Kepler-47 Circumbinary System

Abstract

We have studied the possibility that a third circumbinary planet in the Kepler-47 planetary system be the source of the single unexplained transiting event reported during the discovery of these planets. We applied the MEGNO technique to identify regions in the phase space where a third planet can maintain quasi-periodic orbits, and assessed the long-term stability of the three-planet system by integrating the entire 5 bodies (binary + planets) for 10 Myr. We identified several stable regions between the two known planets as well as a region beyond the orbit of Kepler-47c where the orbit of the third planet could be stable. To constrain the orbit of this planet, we used the measured duration of the unexplained transit event (∼ 4.15 hours) and compared that with the transit duration of the third planet in an ensemble of stable orbits. To remove the degeneracy among the orbits with similar transit durations, we considered the planet to be in a circular orbit and calculated its period analytically. The latter places an upper limit of 424 days on the orbital period of the third planet. Our analysis suggests that if the unexplained transit event detected during the discovery of the Kepler-47 circumbinary system is due to a planetary object, this planet will be in a low eccentricity orbit with a semimajor axis smaller than 1.24 AU. Further constraining of the mass and orbital elements of this planet requires a re-analysis of the entire currently available data including those obtained post-announcement of the discovery of this system. We present details of our methodology and discuss the implication of the results.

An Exo-Jupiter candidate in the eclipsing binary FL Lyr

“…The 2009 times of minima are HJD-2400000 = 54965.02424, 54967.20240, and 54969.38054, and the 2014 times are HJD-2400000 = 56385.18082, 56387.35900, and 56389.53716. 9 We applied the PERDET (PERiod DETermination) code [33].…”

“…The first planet discovered in such a binary was Kepler-16 (AB)b [2]. Others include Kepler-34 (AB)b and Kepler-35 (AB)b [3], Kepler-38 (AB)b [4], Kepler-47 (AB)b Kepler-47 (AB)c [5], PH1-Kepler-64 b [6], Kepler-413 (AB)b [7,8], a possible third planet in the Kepler-47 [9] system and the candidate planet KIC 9632895 (AB)b [10]. Several planets near cataclysmic variables and a planet near the young star FW Tau [1] have also been discovered.…”

Habitability Properties of Circumbinary Planets

“…An observational evidence for the existence of planets outer to those trapped at the edge of the central cavity is provided by the discoveries of such planets as Kepler-47c, Kepler-1647b, and OGLE-2007-BLG-349L(AB)c (Orosz et al, 2012a;Kostov et al, 2013;Hinse et al, 2015;Kostov et al, 2016a;Bennett et al, 2016). The discoveries of such objects demonstrate that not all CBP halt migration at the cavity edge, but some settle at much greater distances from the host binary.…”

“…The discoveries of such objects demonstrate that not all CBP halt migration at the cavity edge, but some settle at much greater distances from the host binary. In the case of the Kepler-47 multiplanet system, there is a lot of space between Kepler-47b and Kepler-47c to harbor possible dynamically stable low-mass planets (Hinse et al, 2015), i.e., the observed two-planet system is in no way closely-packed dynamically. The systems Kepler-1647 and OGLE-2007-BLG-349L(AB) may as well contain low-mass planets in orbits inner to the observed giant planets because the orbits of the former ones are large in size in comparison with the central chaotic zone.…”

No circumbinary planets transiting the tightestKeplerbinaries – a possible fingerprint of a third star

“…Multiplanet stability has been analysed in circumbinary systems (Kratter & Shannon 2013;Hinse et al 2015) but never in the presence of a third star.…”