An aging star sheds its outer layers, leaving behind a dense, hot core the size of Earth — a white dwarf. If remnants of planets, asteroids, or comets orbit nearby, they heat up and begin to glow in the infrared. That extra light is like a warm spot on a cold floor.
Astronomers used data from the Gaia space telescope and ground-based surveys. They measured the glow of 456 white dwarfs within a hundred light-years of the Sun. For 292 of them, the infrared excess is confirmed reliably; the rest are candidates. Three-quarters of these objects were found for the first time.
An interesting detail: among dusty white dwarfs, those with helium atmospheres rather than hydrogen are more common. And the redder the star, the higher the probability. For ordinary white dwarfs, the trend is reversed.
This catalog is the largest and most reliable to date. Nearby dusty white dwarfs are convenient to study further: their disks can reveal what the destroyed planets were made of and how stellar systems die.
A white dwarf the size of Earth can weigh as much as the Sun, a teaspoon of its material would weigh several tons.
In Dan Simmons' novel 'Hyperion,' white dwarfs and their surroundings are mentioned as part of ancient astroengineering structures.