A Precise Radial Velocity Search for Giant Planets orbiting polluted White Dwarfs

Abstract

We present a feasibility study for extending the well-known radial velocity technique to search for planetary companions around white dwarfs. Typically, the spectra of white dwarfs contain only a few pressure-broadened hydrogen and/or helium lines, which do not permit to measure the radial velocity with sufficient precision to detect planets. A small subset of white dwarfs do also show sharp metal lines, presumably from infalling circumstellar material. We suggest to search these “polluted” white dwarfs for possible giant planets using the Doppler reflex motion technique. We show here first results to estimate the Doppler information content from simulated spectra of the metal-polluted WD GD 362.