A Recurrent Infrared Modulation in the Warm Postimpact Debris Disk NGC 2547 ID8

Abstract Extreme debris disks are signposts of violent rocky collisions, but it remains unclear whether their mid-infrared variability traces transient dust clouds or longer-lived postimpact reservoirs. We analyze a 19 yr mid-infrared record of the young solar analog NGC 2547 ID8, combining four spectra from 2007 to 2024 with 3–5 μ m monitoring through 2026. The optically thin mineral surface remains compositionally stable: broad fits spanning multiple grain sizes give 550–577 K, and a common-basis decomposition with T surf fixed at 560 K is dominated by 1 μ m olivine/Mg-olivine and 0.1 μ m forsterite. The W2-equivalent 4.5 μ m excess, traced across six recurrent high states, is instead driven mainly by changes in the hot-base continuum component and defines a 956.8 days infrared recurrence timescale with cycle-to-cycle variations in timing and amplitude. This combination supports the interpretation of ID8 as an early postimpact stage in which material on eccentric orbits repeatedly interacts with a warm rocky reservoir, preserving the impact’s mineral fingerprint while the interaction geometry evolves. Material on eccentric orbits can persist for decades, and possibly longer, while interacting with debris disks. Longer-baseline, higher-cadence infrared monitoring of ID8 will further constrain the stability of its recurrence timescale and the detailed evolution of its infrared variability.