Several decaying asteroids have been found around a distant white dwarf, an old star that our Sun will become in a few billion years. This picture explains the presence of heavy elements on the surfaces of white dwarfs - and shows the bleak end of the Earth.
The white dwarf is the final stage in the evolution of medium-sized stars. These dense objects can weigh as much as the Sun and be as large as the Earth. The attraction on their surface is very high, and calculations show that all elements heavier than helium should rather quickly descend closer to the center of such a star. Despite this, observations have repeatedly found both silicon and iron on the surfaces of white dwarfs.
The reason for this is revealed by a new work by Andrew Vanderburg and his colleagues at the Harvard-Smithsonian Center for Astrophysics. Analyzing observational data from the Kepler space telescope, they drew attention to the unusual behavior of the white dwarf WD 1145 + 017, located in the constellation Virgo. Its regular darkening, which was recorded by Kepler, the authors explained by the presence of at least one (and most likely several) asteroids orbiting the star and decaying in flight.
Now this asteroid orbits already literally above the surface of a half-dead star, completing a full revolution in 4, 5-4, 9 hours. And the closer he comes to a dense dwarf, the more he feels the effect of its gravity and the tidal forces arising from this. Even weak radiation becomes perceptible and begins to evaporate volatiles from its surface. So far, its size is comparable to the size of Ceres, the largest object in the asteroid belt in the solar system. But this is not for long.
Something similar in the distant future may await our home planet. After billions of years, the Sun will use up the main reserves of its "thermonuclear fuel" and destabilize. It will expand and the star will become a red giant, engulfing Mercury and most likely Venus and Earth. The planets and other bodies of the solar system will destabilize, and massive collisions will begin. Then the dying Sun will throw off its outer shells, and the core will shrink, remaining a slowly fading white dwarf, gradually finishing off the remains of what was once its planetary system.