About this world
ZTF J1828+2308 b is a gas giant orbiting ZTF J1828+2308, a hot blue star 658 light-years from Earth. It is about 0.99 times the size of Jupiter and holds 20 Jupiter masses. It completes an orbit every 2.69 hours at 0.0039 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 1,419 K (1,145 °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 2025 by transit with Zwicky Transient Facility. A planet crosses its star and dims it by a tiny, periodic fraction.