We Just Discovered a Scorched Planet That Outlived Its Sun

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Artist's impression of a planet orbiting a white dwarf. NASA

Through the hazy shimmer of a dim white dwarf star that's 410 light-years from Earth, astronomers have peered upon something extraordinary. A planet, closely orbiting this dead star, has apparently survived the cataclysmic implosion that claimed its sun's life.

It's just the second body ever discovered orbiting a perished star, reports The Washington Post.

The planet didn't make it out unscathed; it's a scorched world completely stripped of its outer clothes. Those layers now drift around it like debris around a shipwreck, hinting at its once-rocky planetary glory. Only a metal core of the former world remains intact, but intact it remains — and that's impressive, given what this planet had to endure.

It could be an ominous glimpse into the future for Earth, as our solar system is scheduled to encounter the same fate as this white dwarf did in about 5 billion years.

All stars that are too small to go supernova or collapse into a black hole, like our sun, will eventually run out of their hydrogen fuel and die. Stars don't shuffle off this mortal coil without a fight, however. As their fuel runs dry, these stars balloon to massive sizes, called red giants, which consume the orbits of nearby planets. In our solar system, Mercury and Venus are sure to be completely swallowed up. Earth will get charred as well.

With a little luck, though, Earth's metal core might get spit out intact, too, like this faraway planetoid.

After the red giant phase, our sun will convulse and peter out, eventually shriveling down to a mass about the size of our planet that dimly glows, a shell of the once-radiant star it was.

That's what has happened to the white dwarf, known as SDSS J122859.93+104032.9, survived by its cold metal planetoid.

"We have this glimpse into our possible future," said Jessie Christiansen, an astronomer at NASA's exoplanet science institute who wasn't involved in the new study. "It's exciting, and you can imagine that happening here."

This unusual discovery was found using the world's largest optical telescope, the Gran Telescopio Canarias in Spain. The dead solar system was flagged after it was noticed that its light signature was consistently being disrupted by an orbiting stream of gas, which we now know was the debris that surrounded the surviving metal planet. The discovery by astronomers at the University of Warwick in England was published in the journal Science.

Due to this planet's close orbit to its sun and the surprising fact that it survived the death of its sun, researchers surmise that it must be incredibly dense, most likely a solid ball of iron.

Scientists now want to find other worlds like this one in the hope of better understanding the fate of our own solar system. Given that clouds of debris are common to see around white dwarfs, there's hope that the galaxy is filled with such sustaining worlds, which might improve the odds that our solar system will also survive the sun's death.

"All of that suggests that up to half of all white dwarfs have planetary systems that survived their evolutions and are flinging in material," said Christopher Manser, one of the study's astrophysicists.

And if planetary systems can survive around their white dwarf stars, there's optimism that life might experience a second genesis while circling around them too. It's a warming thought, that life in our solar system might live on even after the sun dies.