About this world
GJ 9827 d is a super-Earth orbiting GJ 9827, an orange dwarf (type K7V) 96.7 light-years from Earth. It is about 2 times the size of Earth and holds 3 Earth masses. It completes an orbit every 6.2 days at 0.053 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 675 K (402 °C): far too hot for liquid water on its surface. By the "cosmic shoreline", its star has probably stripped its atmosphere away, leaving bare rock. Its atmosphere has already been studied: 7 spectroscopic observations, all of them with the James Webb Space Telescope.
It was discovered in 2017 by transit with K2. A planet crosses its star and dims it by a tiny, periodic fraction. GJ 9827 has 3 known planets; the others are GJ 9827 b and GJ 9827 c.