Sporadic Dips from Extended Debris Transiting the Metal-Rich White Dwarf SBSS 1232+563

TL;DR

This paper reports the discovery of sporadic, deep transits caused by debris around the metal-rich white dwarf SBSS 1232+563, revealing that such transits can be infrequent and vary over years.

Contribution

It provides the first long-term observational evidence that debris transits around white dwarfs are sporadic and can include large-amplitude events after years of inactivity.

Findings

Deep, sporadic transits observed over 25 years.

An 8-month-long dimming event caused >40% flux drop.

No significant change in elemental abundances over two decades.

Abstract

We present the discovery of deep but sporadic transits in the flux of SBSS 1232+563, a metal-rich white dwarf polluted by disrupted exoplanetary debris. Nearly 25 years of photometry from multiple sky surveys reveal evidence of occasional dimming of the white dwarf, most notably evident in an 8-months-long event in 2023 that caused a >40% drop in flux from the star. In-transit follow-up shows additional short-timescale (minutes- to hours-long) dimming events. TESS photometry suggests a coherent 14.842-hr signal that could represent the dominant orbital period of debris. Six low-resolution spectra collected at various transit depths over two decades show no evidence of significant changes in the observed elemental abundances. SBSS 1232+563 demonstrates that debris transits around white dwarfs can be sporadic, with many years of inactivity before large-amplitude dimming events.