Overview

• Hubble ultraviolet spectroscopy of WD 1647+375 identifies volatile-rich debris with the highest nitrogen abundance yet seen in a white dwarf debris system (~5.1% by mass).
• An oxygen excess (~84%) and a water-to-rock ratio of about 2.45 point to a water-rich composition consistent with a fragment of a Kuiper-belt-like dwarf planet.
• The white dwarf has been accreting at roughly 2×10^8 grams per second for at least 13 years, implying a minimum parent-body mass near 10^17 grams.
• Researchers report the debris is about 64% water ice, suggesting material from the crust or mantle of an exo-Pluto–type object.
• The object's total mass and origin remain unresolved, and the team plans James Webb observations to probe molecular volatiles in infrared light.