About this world
51 Peg b is a gas giant orbiting 51 Peg, a yellow, Sun-like star (type G5V) 50.4 light-years from Earth. It is about 1.3 times the size of Jupiter (its size estimated from its mass) and holds 0.61 Jupiter masses. It completes an orbit every 4.23 days at 0.052 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 1,329 K (1,056 °C): far too hot for liquid water on its surface. At its size it almost certainly keeps a deep envelope of hydrogen and helium.
It was discovered in 1995 by radial velocity with Haute-Provence Observatory. The star wobbles toward and away from us, Doppler-shifting its spectrum.