Kepler-56b is about 0.1028 AU (9.56 million mi; 15.38 million km) away from its host star[1] (about one-tenth of the distance between Earth to the Sun), making it even closer to its parent star than Mercury (0.39 AU [36 million mi; 58 million km]) and Venus (0.72 AU [67 million mi; 110 million km]). It takes 10.5 days for Kepler-56b to complete a full orbit around its star.[1] Further research shows that Kepler-56b's orbit is about 45° misaligned to the host star's equator. Later radial velocitymeasurements have revealed evidence of a gravitational perturbation from Kepler-56d.
Both Kepler-56b and Kepler-56c will be devoured by their parent star in about 130 and 155 million years.[4] Even further research shows that it will have its atmosphere boiled away by intense heat from the star, and it will be stretched by the strengthening stellar tides.[4]
The measured mass of Kepler-56b is about 30% larger than Neptune's mass, but its radius is roughly 70% larger than Neptune's. Therefore, Kepler-56b should have a hydrogen/helium envelope containing a significant fraction of its total mass.[5][6] Like Kepler-11b and Kepler-11c, the envelope's light elements are susceptible to photo-evaporation caused by radiation from the central star. For example, it has been calculated that Kepler-11c lost over 50% of its hydrogen/helium envelope after formation.[7] However, the larger mass of Kepler-56b, compared to that of Kepler-11c, reduces the efficiency of mass loss.[7] Nonetheless, the planet may have been significantly more massive in the past and may keep losing mass in the future.
Steffen, Jason H; Fabrycky, Daniel C; Agol, Eric; et al. (20 August 2012). "Transit Timing Observations from Kepler: VII. Confirmation of 27 planets in 13 multiplanet systems via Transit Timing Variations and orbital stability". Mon. Not. R. Astron. Soc. 428 (2): 1077. arXiv:1208.3499. Bibcode:2013MNRAS.428.1077S. doi:10.1093/mnras/sts090.