When a star like the Sun ages, it swells and sheds its outer layers. What remains is a small, dense white dwarf — the former core. Around it, planetary debris can remain: rocks, dust, even whole asteroids. They orbit like a carousel that's been taken apart, but the pieces are still spinning.
Astronomers watched the white dwarf WD 1054-226 for six years. Its light dims every 25 hours and 23 minutes. It's as if a rotating disk with slits were passing in front of a lamp. This means there's a dense ring of debris around the star, not just a cloud of dust. The ring is tilted edge-on to us, so we see it blocking the light.
Earlier, astronomers noticed another signal: every 11.4 hours. But it's absent in the new data. It seems that piece of the ring broke apart or drifted away. The two main signals, however, remain stable. This suggests the ring's structure isn't random: it's held in place by gravity, possibly from an unseen shepherd planet that gathers debris into a narrow band.
Such systems are living laboratories. They show what happens to planetary systems after a star dies. Perhaps our own Sun, billions of years from now, will leave behind a similar ring made from what was once Earth and Mars.
The white dwarf WD 1054-226 is so small that its diameter is less than the distance from Moscow to St. Petersburg, yet it's almost as massive as the Sun.
Arthur C. Clarke's novel "Rendezvous with Rama" describes an artificial structure spinning around a star — somewhat like this natural ring of debris.