KEPLER-413B: A SLIGHTLY MISALIGNED, NEPTUNE-SIZE TRANSITING CIRCUMBINARY PLANET

International audienceWe report the discovery of a transiting, R-p=4.347 +/- 0.099R circle plus, circumbinary planet (CBP) orbiting the Kepler K+M eclipsing binary (EB) system KIC 12351927 (Kepler-413) every similar to 66 days on an eccentric orbit with a(p)=0.355 +/- 0.002 AU, e(p)=0.118 +/- 0.002. The two stars, with M-A=0.820 +/- 0.015M circle dot, R-A=0.776 +/- 0.009R circle dot and M-B=0.542 +/- 0.008M circle dot, R-B=0.484 +/- 0.024R circle dot, respectively, revolve around each other every 10.11615 +/- 0.00001 days on a nearly circular (e(EB)=0.037 +/- 0.002) orbit. The orbital plane of the EB is slightly inclined to the line of sight (i(EB)= 87 degrees.33 +/- 0 degrees.06), while that of the planet is inclined by similar to 2 degrees.5 to the binary plane at the reference epoch. Orbital precession with a period of similar to 11 yr causes the inclination of the latter to the sky plane to continuously change. As a result, the planet often fails to transit the primary star at inferior conjunction, causing stretches of hundreds of days with no transits corresponding to multiple planetary orbital periods). We predict that the next transit will not occur until 2020. The orbital configuration of the system places the planet slightly closer to its host stars than the inner edge of the extended habitable zone. Additionally, the orbital configuration of the system is such that the CBP may experience Cassini State dynamics under the influence of the EB, in which the planet's obliquity precesses with a rate comparable to its orbital precession. Depending on the angular precession frequency of the CBP, it could potentially undergo obliquity fluctuations of dozens of degrees (and complex seasonal cycles) on precession timescales