Washington: Astronomers have now confirmed the presence of Kepler-88 c, an unseen planet that had been previously predicted thanks to the gravitational perturbation it caused on its transiting brother planet, Kepler-88 b.
Searching for periodic transits in hundreds of thousands of stars was the primary goal of the Kepler space telescope. More than 3,500 of such periodic transits were found during the 4 years of the mission.
Planets that share the same host star gravitationally interact with each other. This interaction between planets can cause perturbations in the predicted times of transit of planets in multi-planetary systems.
Lead author Susana Barros, a researcher at the Laboratoire d`Astrophysique de Marseille (LAM), said that this is called transit timing variations (TTV).
The TTV technique is sensitive to planets in multiple systems down to the mass of the Earth, and can therefore be used to unveil the existence of non-transiting planets, that cause perturbations in the orbital motion of transiting planets.
A careful analysis of the dynamical interaction between planets, previously performed by a team led by David Nesvorny (Southwest Research Institute), predicted that this system had two planets near a two-to-one resonance (the orbital period of the unseen outer planet is exactly two times longer than the transiting inner planet).
Using the SOPHIE velocimeter, the team independently measured the mass of Kepler-88 c.
The inferred mass for the unseen planet is in perfect agreement with the value that was predicted from TTV.
