Kepler-47b

Kepler-47b is a gas giant, an exoplanet that is near the same mass and radius as the planets Jupiter and Saturn.^[4] It has a temperature of 449 K (176 °C; 349 °F).^[5] The planet has a radius of 3.03 R_🜨, and is thought to have no solid surface.^[6] It has a mass of 8.43 M_🜨.

The planet orbits in a circumbinary orbit around a (G-type) and (M-type) binary star system. The stars orbit each other about every 7.45 days.^[2] The stars have masses of 1.04 M_☉ and 0.35 M_☉ and radii of 0.96 R_☉ and 0.35 R_☉, respectively.^[2][1] They have temperatures of 5636 K and 3357 K.^[2][1] Based on the stellar characteristics and orbital dynamics, an estimated age of 4–5 billion years for the system is possible. In comparison, the Sun is about 4.6 billion years old^[7] and has a temperature of 5778 K.^[8] The primary star is somewhat metal-poor, with a metallicity ([Fe/H]) of −0.25, or 56% of the solar amount.^[1] The stars' luminosities (L_☉) are 84% and 1% that of the Sun.^[2][1]

The apparent magnitude of the system, or how bright it appears from Earth's perspective, is about 15.8. Therefore, it is too dim to be seen with the naked eye.

Kepler-47b orbits around its parent stars every 45 days at a distance of 0.29 AU from its stars (close to where Mercury orbits from the Sun, 0.39 AU), which is the smallest known circumbinary orbit of any planet.^[9] It receives about 9.6 times as much sunlight that Earth does from the Sun.^[5]

Kepler-47b, as well as Kepler-47c, was first discovered by scientists, from both NASA and the Tel-Aviv University in Israel, using the Kepler space telescope.^[10] Additionally, the planetary characteristics of both objects were identified by a team of astronomers at the University of Texas at Austin's McDonald observatory.^[6] Both planets were discovered after transiting their parent stars, and they both seem to be orbiting along the same plane.^[10]