The host star is running out of hydrogen in the core, swells up, and its surface becomes cooler. It is also losing mass, which causes the planets to move further out. The perturbation of the orbits may lead to collisions that will generate large amounts of rocky debris. Credit: Mark A. Garlick, space-art.co.uk/University of Warwick
WARWICK, England, May 3 (UPI) -- Dust from destroyed planets that once orbited dwarf stars suggests the shattered worlds were similar in composition to Earth, British astrophysicists say.
University of Warwick scientists using the Hubble Space Telescope to study the chemical composition of the atmospheres of white dwarf stars found the most frequently occurring elements in the dust around four white dwarfs observed were oxygen, magnesium, iron and silicon -- the four elements that make up roughly 93 percent of the Earth.
"What we are seeing today in these white dwarfs several hundred light years away could well be a snapshot of the very distant future of the Earth," Warwick astrophysicist Boris Gansicke said in a university release Thursday.
"As stars like our sun reach the end of their life, they expand to become red giants when the nuclear fuel in their cores is depleted," he said.
The orbits of the planets could become destabilized by this, he said, causing collisions that could shatter entire worlds, leaving fragments and dust around the star with chemical composition mirroring that of the destroyed planets.
One of the white dwarf stars studied stood out from the rest owing to the relative overabundance of the elements iron, nickel and sulphur in the dust surrounding it, researchers said.
"It is entirely feasible that in [white dwarf star] PG0843+516 we see the accretion of such fragments made from the core material of what was once a terrestrial exoplanet."
