Formation of undermassive single white dwarfs and the influence of planets on late stellar evolution

We propose a scenario to form low-mass, single, slow rotating white dwarfs from a solar-like star accompanied by a massive planet, or a brown dwarf, in a relatively close orbit (e.g. HD 89707). Such white dwarfs were recently found by Maxted & Marsh (1998). When the solar-like star ascends the giant branch it captures the planet and the subsequent spiral-in phase expels the envelope of the giant leaving a low-mass helium white dwarf remnant. In case the planet evaporizes, or fills its own Roche-lobe, the outcome is a single undermassive white dwarf. The observed distribution of planetary systems supports the applicability of this scenario....