ASK Space

EXOPLANETS

Can planets form around dead stars?

The majority of stars will end their lives as white dwarfs, and it is expected that a large fraction of their planetary systems will survive this stellar evolution. There are theories that planets could form from recycled planetary material around white dwarfs, but none have been discovered so far.

However, for evidence of planets that have formed around a dead star, one only has to look at the first exoplanetary system discovered, around the neutron star PSR B1257+12. The planets in this system orbit very close in – the farther planet orbiting PSR B1257+12 orbits at 0.46 astronomical units, or AU; the Earth orbits at one AU – and must have formed after the neutron star, as any previous planetary system would not have survived the birth of the neutron star.

While neutron stars can be formed through multiple channels, one possible scenario is that PSR B1257+12 and its planetary system were