The Influence of Tidal Heating on the Habitability of Planets Orbiting White Dwarfs

In recent years, there have been a growing number of observations indicating the presence of rocky material in short-period orbits around white dwarfs. In this Letter, we revisit the prospects for habitability around these post-main-sequence star systems. In addition to the typically considered radiative input luminosity, potentially habitable planets around white dwarfs are also subjected to significant tidal heating. The combination of these two heating sources can, for a narrow range of planetary properties and orbital parameters, continuously maintain surface temperatures amenable for habitability for planets around white dwarfs over timescales up to 10 Gyr. We show that for a specific locus of orbital parameter space, tidal heating can substantially extend the timescale of continuous habitability for a planet around a white dwarf.