Overview

• The findings, published September 18 in MNRAS and detailed on arXiv, identify WD 1647+375 about 260 light-years away as accreting volatile‑rich debris.
• Spectra show an oxygen excess of about 84% over rock expectations, an inferred ~64% water‑ice fraction, and a nitrogen mass fraction near 5%—the highest yet seen in white dwarf debris—along with carbon and sulfur.
• The accretion has persisted for at least 13 years at roughly 2 × 10^8 grams per second, implying a minimum parent‑body mass of ~10^17 grams and potentially much more if the episode lasts longer.
• Researchers interpret the material as most consistent with a fragment from the crust or mantle of a Kuiper‑belt‑analog dwarf planet, though an interstellar capture cannot be ruled out by composition alone.
• This is reported as the first unambiguous case of a hydrogen‑atmosphere white dwarf accreting an icy planetesimal, underscoring the unique role of ultraviolet spectroscopy and motivating infrared follow‑up with JWST.