A planetesimal orbiting within the debris disc around a white dwarf star

Area of Science:

• Astronomy and Astrophysics
• Exoplanetary Science

Background:

• White dwarf stars are remnants of Sun-like stars and can accrete material from surrounding bodies.
• Some white dwarf systems possess gaseous debris discs, detectable via emission lines, indicating past accretion events.
• The study of these debris discs provides insights into the composition and evolution of planetary systems around stellar remnants.

Purpose of the Study:

• To investigate the nature of gaseous debris discs around white dwarf stars.
• To analyze periodic variations in emission line profiles from the debris disc around white dwarf SDSS J122859.93+104032.9.
• To determine the origin of the observed short-period signal within the debris disc.

Main Methods:

• Observational astronomy utilizing spectroscopy to analyze emission line profiles.
• Time-series analysis to detect periodic variations in spectral data.
• Modeling of debris disc dynamics and composition.

Main Results:

• A stable 123.4-minute periodic variation was detected in the Ca ii emission line profiles of the debris disc.
• The signal's characteristics suggest the presence of a compact, solid body within the disc.
• The observed periodicity is consistent with a planetesimal held together by its own internal strength.

Conclusions:

• The findings provide strong evidence for the existence of a planetesimal within the debris disc of SDSS J122859.93+104032.9.
• This planetesimal is likely a remnant of the star's planetary system, surviving the star's evolution.
• The study highlights the potential for white dwarf systems to harbor intact planetary bodies, offering a unique laboratory for studying planetary system evolution.