First double gas ring discovered around a white dwarf

An international team led by the University of Trieste has discovered, for the first time, two concentric rings of gas around a white dwarf star, WD J1328−1450, located about 1,600 light-years from Earth. The structure, observed using the X-shooter spectrograph on the Very Large Telescope in Chile, has remained stable for over two years and shows two rings separated by a gas-free zone.

According to the study published in Nature Astronomy, the two rings are likely shaped by the gravitational influence of two intact planetary bodies that survived the destruction of their stellar system. The inner body could be as large as an asteroid, while the outer one might reach sizes comparable to Ceres, Pluto, or even the Moon.

White dwarfs are the extremely dense stellar remnants left behind when a Sun-like star exhausts its nuclear fuel. During this transformation, planets and asteroids in the system can be destroyed, leaving fragments that continue to orbit for billions of years. Until now, 21 systems with gaseous disks around white dwarfs were known, but all exhibited a single disk structure.

The discovery of WD J1328−1450 represents a unique case because it shows, for the first time, a dual configuration. Researchers observed this star between 2021 and 2023, noting that it emitted more infrared radiation than expected, a typical signal of orbiting dust. Spectroscopic analysis revealed four peaks instead of the usual two, indicating two distinct rings.

This discovery not only shows how complex structures can survive around dead stars but also offers a possible scenario for the fate of our Solar System billions of years from now, when the Sun itself becomes a white dwarf.