Frequency of debris discs around white dwarfs

The Frequency of Debris Disks at White Dwarfs

Metallicity-unbiased survey of cool, hydrogen-atmosphere white dwarfs. The inferred debris disc frequency is 4.3^+2.7_-1.2%, which they interpret either as a lower limit on the frequency of planetary systems around the progenitor stars (progenitor masses 1–7 M_⊙) or alternatively the fraction of the white dwarf lifetime where the white dwarf undergoes accretion, assuming a 100% frequency for planetary systems.