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Transiting Planetary Debris around White Dwarfs: New Discoveries and Emerging Dichotomies

Presentation #612.01 in the session Planets around Compact Objects.

Published onApr 03, 2024
Transiting Planetary Debris around White Dwarfs: New Discoveries and Emerging Dichotomies

More than 30% of white dwarf stars are estimated to be accreting disrupted planetary material from their metal-polluted spectra. The original, intact bodies eluded detection until 2015 when K2 observations of up to 40% deep transits towards the white dwarf WD 1145+017 were published, providing the first evidence for the ongoing tidal disruption of a planetary object around a polluted white dwarf. Light curves from the Zwicky Transient Facility, Gaia, and TESS are driving the discovery of more transiting systems towards polluted white dwarfs. We showcase new follow-up photometry, including the discovery of a 5-hr transiting debris system, the fifth measured orbital period within this emerging class and the shortest since the discovery of WD 1145+017 (4.5-hr). We also highlight the discovery of deep, potentially years-long recurring transits towards another white dwarf. Altogether, these discoveries illuminate a dichotomy of either “short” (near the tidal disruption radius) or “long” (100s of days or longer) recurrence timescales. Separately, there are two distinct cases of light curve morphologies: systems showing extended phases out of transit versus systems that appear to be continuously transited by debris. We believe measuring the orbital periods of transiting debris will be a key to better understanding the broader phenomenon of white dwarf metal pollution. Observing transits across a distribution of periods with a variety of light curve morphologies could help constrain the dynamics of both evolved debris disks and objects just beginning to undergo tidal disruption, and thus place limits on the still incomplete roadmap to pollution onto white dwarf photospheres.

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