Doppler-imaging of the planetary debris disc at the white dwarf SDSS J122859.93+104032.9

TL;DR

This study presents twelve years of optical spectroscopy of the white dwarf SDSS J1228+1040, revealing a precessing gaseous debris disc with variable emission lines consistent with relativistic effects.

Contribution

The paper provides the first detailed Doppler tomography analysis of a white dwarf debris disc, linking observed spectral variations to relativistic precession.

Findings

Detection of multiple ionic emission lines indicating disc composition.

Identification of a 24-30 year precession period of the debris disc.

Spectral variations consistent with general relativistic precession effects.

Abstract

Debris discs which orbit white dwarfs are signatures of remnant planetary systems. We present twelve years of optical spectroscopy of the metal-polluted white dwarf SDSS J1228+1040, which shows a steady variation in the morphology of the 8600 {\AA} Ca II triplet line profiles from the gaseous component of its debris disc. We identify additional emission lines of O I, Mg I, Mg II, Fe II and Ca II in the deep co-added spectra. These emission features (including Ca H & K) exhibit a wide range in strength and morphology with respect to each other and to the Ca II triplet, indicating different intensity distributions of these ionic species within the disc. Using Doppler tomography we show that the evolution of the Ca II triplet profile can be interpreted as the precession of a fixed emission pattern with a period in the range 24-30 years. The Ca II line profiles vary on time-scales that are broadly consistent with general relativistic precession of the debris disc.