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article imageStudy: Four white dwarf stars swallowing up Earth-like exoplanets

By Andrew Moran     May 3, 2012 in Science
Warwick - Astrophysicists at the University of Warwick have discovered four white dwarf stars that are surrounded by cosmic dust from shattered planetary bodies. One star is in the process of consuming an Earth-like exoplanet.
A white dwarf, also known as a degenerate dwarf, is the final evolutionary state of a small star that is composed mostly of electron-degenerate matter. These stars are identical to our sun because they are dense and share a similar mass.
University of Warwick astronomers have published a paper in the Royal Astronomical Society (RAS) that identifies four nearby white dwarfs that are surrounded by cosmic dust that appear to be the remnants of rocky exoplanets similar to the Earth.
The researchers found that the dust consisted of four elements that make up 93 percent of our planet: iron, magnesium, oxygen and silicon. It is also composed of small quantities of carbon, which is the first time that such matter had been discovered in the atmosphere of white dwarfs polluted by debris.
One particular white dwarf does stand out, PG0843+516, because it has a plethora of iron, nickel and sulphur elements. Iron and nickel are found in the cores of the planets, while the pull of the gravity formation is due to the elements sinking to the centre. The same applies to sulphur.
Scientists are now proposing that this could be our planet’s future and inevitable demise. Our sun will eventually expand and engulf Mercury, Venus and Earth. It could devour terrestrial planets and form asteroids. Jupiter, though, would survive the sun’s transformation.
“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. 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,” said Boris Gänsicke, professor of the Department of Physics at the University of Warwick and lead study author.
“When this happens in our own solar system, billions of years from now, the Sun will engulf the inner planets Mercury and Venus. It’s unclear whether the Earth will also be swallowed up by the Sun in its red giant phase - but even if it survives, its surface will be roasted.”
Once our sun transitions into a white dwarf, the planets will move outwards, which will create total chaos in our solar system akin to our early days where planetary bodies collided and realigned and asteroids struck everything in their path.
More about white dwarf stars, Exoplanets, royal astronomical society, Earth, Sun
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