2014/09/10 by David J. Wilson, David J Wilson, Boris Gaensicke +11 · 3 citations
Physics and Astronomy · #Astro and Planetary Science #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Blue dwarf #Cataclysmic variable star #Physics #Stars #Stellar, planetary, and galactic studies #Variable (mathematics) #Variable star #White dwarf #astro-ph.SR
paper · pdf · doi:10.1093/mnras/stu1876
Accepted for publication in MNRAS
arxiv created 2014/09/10 · openalex publication_date 2014/10/14 · arxiv updated 2015/06/22 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We present the discovery of strongly variable emission lines from a gaseous disc around the DA white dwarf SDSS J1617+1620, a star previously found to have an infrared excess indicative of a dusty debris disc formed by the tidal disruption of a rocky planetary body. Time-series spectroscopy obtained during the period 2006-2014 has shown the appearance of strong double-peaked Ca II emission lines in 2008. The lines were weak, at best, during earlier observations, and monotonically faded through the remainder of our monitoring. Our observations represent unambiguous evidence for short-term variability in the debris environment of evolved planetary systems. Possible explanations for this extraordinary variability include the impact onto the dusty disc of either a single small rocky planetesimal, or of material from a highly eccentric debris tail. The increase in flux from the emission lines is sufficient that similar events could be detected in the broadband photometry of ongoing and future large-area time domain surveys.