ホット・ジュピター
Kepler-40b is a Hot Jupiter that is estimated to be 2.2 times the mass of Jupiter (over 700 times the mass of Earth), but 1.17 times Jupiter's radius (13.12 times the radius of Earth). Thus, the planet has a density of 1.68 grams per cubic centimeter, similar to that of Neptune (1.638 g/cm3). The planet's equilibrium temperature was initially estimated to be 1620 K, thirteen times hotter than Jupiter's equilibrium temperature. In 2015, the planetary nightside temperature was modeled to be even hotter at 2327 K.