COOL CUSTOMERS IN THE STELLAR GRAVEYARD. III. LIMITS TO SUBSTELLAR OBJECTS AROUND NEARBY WHITE DWARFS USING THE CANADA-FRANCE-HAWAII TELESCOPE

Results from a ground-based high-contrast imaging survey of 13 nearby white dwarfs for substellar objects are presented. We place strict upper limits on the type of substellar objects present, ruling out the presence of anything larger than ~14MJ for eight of the white dwarfs at separations >19 AU and corresponding to primordial separations of ~3.6 AU assuming adiabatic mass loss without tidal interactions. With these results we place the first upper limit on the number of intermediate-mass stars with brown dwarfs at separations >13 AU. We combine these results with previous work to place upper limits on the number of massive Jovian (>10MJ) planets in orbit around white dwarfs whose progenitors spanned a mass range of 17 M.