About this world
GJ 1148 b is a gas giant orbiting GJ 1148, a cool red dwarf (type M5) 35.9 light-years from Earth. It is about 1.1 times the size of Jupiter (its size estimated from its mass), with at least 0.3 Jupiter masses (a minimum, measured by radial velocity). It completes an orbit every 41.4 days at 0.17 AU from its star, closer than Mercury is to the Sun, on a strongly elongated orbit (e = 0.38).
Its equilibrium temperature is about 233 K (−40 °C), which places it in the conservative habitable zone: the band where liquid water could exist on a rocky surface. At its size it almost certainly keeps a deep envelope of hydrogen and helium.
It was discovered in 2010 by radial velocity with W. M. Keck Observatory. The star wobbles toward and away from us, Doppler-shifting its spectrum. GJ 1148 has 2 known planets; the others are GJ 1148 c.