Relentless and Complex Transits from a Planetesimal Debris Disk

Understand

This article reports quasi-continuous transiting events towards WD 1054-226 at d=36.2 pc and V=16.0 mag, based on simultaneous, high-cadence, multi-wavelength imaging photometry using ULTRACAM over 18 nights from 2019 to 2020 March.

• The predominant period is 25.02 h, and corresponds to a circular orbit with blackbody Teq = 323 K, where a planetary surface can nominally support liquid water.
• The light curves reveal remarkable night-to-night similarity, with changes on longer timescales, and lack any transit-free segments of unocculted starlight.
• The most pronounced dimming components occur every 23.1 min -- exactly the 65th harmonic of the fundamental period -- with depths of up to several per cent, and no evident color dependence.