White dwarf, An old, extremely dense star of faint luminosity, formed by the nucleus of a red giant ... [+] contracting until it reaches the size of Earth. Rather than trying to study exoplanets, the work looks at white dwarf stars. A white dwarf is the remnant of a Sun-like star that has collapsed under its gravitational weight. The gravity of a white dwarf is so strong that the heavy elements of the star sink to its core. This means that the exoplanets likely had a similar composition, and therefore similar geology.

Source: Forbes October 19, 2019 15:56 UTC