About this world
HAT-P-17 c is a gas giant orbiting HAT-P-17, an orange dwarf (type K) 301 light-years from Earth. It is about 1.2 times the size of Jupiter (its size estimated from its mass), with at least 3.4 Jupiter masses (a minimum, measured by radial velocity). It completes an orbit every 15.3 years at 5.6 AU from its star, on a strongly elongated orbit (e = 0.39).
Its equilibrium temperature is about 100 K (−174 °C): too cold for liquid water on its surface. At its size it almost certainly keeps a deep envelope of hydrogen and helium.
It was discovered in 2012 by radial velocity with W. M. Keck Observatory. The star wobbles toward and away from us, Doppler-shifting its spectrum. HAT-P-17 has 2 known planets; the others are HAT-P-17 b.