Remnant planetary systems around bright white dwarfs

We cross-correlate several sources of archival photometry for 1265 bright (V ∼ 16 mag) white dwarfs (WDs) with available high signal-to-noise spectroscopy. We find 381 WDs with archival Spitzer+IRAC data and investigate this subsample for infrared excesses due to circumstellar dust. This large data set reveals 15 dusty WDs, including three new debris discs and the hottest WD known to host dust (WD 0010+280). We study the frequency of debris discs at WDs as function of mass. The frequency peaks at 12.5 per cent for 0.7–0.75 M⊙ WDs (with 3 M⊙ main-sequence star progenitors) and falls off for stars more massive than this, which mirrors predicted planet occurrence rates for stars of different masses