About this world
HD 97658 b is a sub-Neptune orbiting HD 97658, an orange dwarf (type K1V) 70.3 light-years from Earth. It is about 2.1 times the size of Earth and holds 8.3 Earth masses. It completes an orbit every 9.49 days at 0.081 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 751 K (478 °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.
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.