A team led by Nicola Gentile Fusillo, of the University of Trieste and associated with Italy’s National Institute for Astrophysics (INAF), has discovered the first double debris disc around a white dwarf, the star J1328−1450. The study was published in Nature Astronomy.
White dwarfs are what remains of stars like the Sun after they run out of fuel. Until now, discs found around them showed the signature of a single disc. In this case there are two concentric rings separated by a clear gap.
The observations were made with the X-shooter spectrograph on ESO’s Very Large Telescope, in Chile’s Atacama Desert. The rings contain calcium, oxygen, magnesium and iron, but only the inner one has gaseous magnesium, suggesting two different source bodies.
According to the authors, the inner ring was formed by a body a few kilometres across, the size of an asteroid, and the outer one by an object that could be as large as Pluto or the Moon. The system helps us understand what may happen to planetary systems like ours in the distant future.
