According to research published in the Monthly Notices of the Royal Astronomical Society, planets that have been stripped down to their cores by their stars interact with that star (likely at the end of its lifespan and thus, a white dwarf) and send out radio waves, thanks to the magnetic field between the two celestial bodies.
“There is a sweet spot for detecting these planetary cores: a core too close to the white dwarf would be destroyed by tidal forces, and a core too far away would not be detectable," the study's lead author, Dimitri Veras, said in a statement.
(AP) FROZEN EARTHLIKE PLANETS COULD SUPPORT LIFE: STUDY "Also, if the magnetic field is too strong, it would push the core into the white dwarf, destroying it," Veras continued.
"Hence, we should only look for planets around those white dwarfs with weaker magnetic fields at a separation between about 3 solar radii and the Mercury-Sun distance."
It's still unclear how long the planetary cores can survive after the planet is stripped by the star.
Veras added that no one has yet found the "bare core" of a major planet before, a major planet via magnetic signatures or a major planet around a white dwarf.
“We will use the results of this work as guidelines for designs of radio searches for planetary cores around white dwarfs," Wolszczan commented.