We all know that the end of the world will eventually come, but if the apocalypse is caused by our sun, fortunately it won’t be for another five billion years.
That said, scientists have seen for the first time what it will be like when our star runs out of fuel, engulfing Mercury, Venus and possibly Earth in its wake.
That’s because they spotted a star engulfing a planet just 12,000 light-years away in our own Milky Way galaxy, near the eagle-like constellation of Aquila.
Astronomers had previously observed stars just before and shortly after they gobbled up entire planets, but until now they had never caught one in the act.
It was identified when experts spotted a star that grew more than 100 times brighter in just 10 days, before quickly fading away.
Terrifying: Scientists have seen a star swallow a planet just 12,000 light-years away in our own Milky Way galaxy, near the eagle-like constellation of Aquila (shown in an artist’s impression)
More mysteriously, this white-hot flash was followed by a colder, longer-lasting signal, which led astronomers to their exciting conclusion.
They said the combination of the two events could only have been caused by a star engulfing a nearby planet that was likely a hot Jupiter-sized world.
It would have been drawn into the dying star’s atmosphere and then consumed at its core.
“We saw the final stage of swallowing,” said lead author Kishalay De of MIT’s Kavli Institute for Astrophysics and Space Research.
As terrifying as it may seem, the observation is a sobering glimpse into Earth’s fate.
While this won’t happen for billions of years, when the sun burns up, it will engulf the inner planets of the solar system and become a white dwarf.
This is a small, dense remnant of a star glowing with leftover heat.
“We see the future of the Earth,” De said.
“If another civilization were to observe us from 10,000 light-years away as the sun engulfs the Earth, they would see the sun suddenly brighten up as it ejects some material, then forms dust around it, before falling back into what it was. ‘
Researchers from MIT, Harvard University and Caltech discovered the planet-eating star in May 2020, after sifting through data from the Zwicky Transient Facility (ZTF) at Caltech’s Palomar Observatory in California.
However, it took another 12 months for them to figure out exactly what was going on.
The ZTF scans the sky for stars rapidly changing in brightness, which could be signatures of supernovae, gamma-ray bursts and other stellar phenomena.
The was searching the ZTF data when he made the discovery.
“One night I saw a star out of nowhere that got brighter by a factor of 100 over the course of a week,” he said.
“It was unlike any starburst I’d seen in my life.”
How it happens: This image shows the process of a Sun-like star changing from a planet orbiting it (left) to gradually expanding as it runs out of fuel and drags the planet into it
To confirm exactly what he had seen, De began comparing it to other observations of the same star made by Hawaii’s Keck Observatory.
However, that only confused him more.
He found traces of “peculiar molecules” that can only exist at very cold temperatures.
“These molecules can only be seen in stars that are very cold,” said De. And when a star gets brighter, it usually gets hotter.
‘So low temperatures and glowing stars don’t go together.’
It wasn’t until about a year after his initial discovery that things started to make sense, when De and his colleagues began analyzing data related to the star from an infrared camera at the Palomar Observatory.
“That infrared data made me fall off my chair,” he said. “The source was insanely bright in the near-infrared.”
The analysis revealed that after the first hot flash, the star began to emit colder energy, which the astronomers say was likely the star’s gas rocketing into space and condensing into dust.
This made it cold enough to be detected at infrared wavelengths.
Initially, De and his colleagues thought it was two stars merging, until data from NASA’s infrared space telescope, NEOWISE, helps them reach a much more exciting conclusion.
They estimate that since its initial outburst, the star had released a surprisingly small amount of energy — about 1/1,000 the size of a previously observed stellar merger.
“That means anything that merged with the star must be 1,000 times smaller than any other star we’ve seen,” De said.
And it is a happy coincidence that the mass of Jupiter is about 1/1000 of the mass of the Sun. Then we realized: this was a planet colliding with its star.’
The scientists suddenly realized that the bright, incendiary flash was likely the final moments of a Jupiter-sized planet being pulled into the ballooning atmosphere of a dying star.
The cold dust was then caused by the planet falling into the star’s core, blowing away the outer layers of the star.
“For decades, we’ve been able to see the before and after,” said De.
‘In the past, when the planets are still orbiting very close to their star, and after that, when a planet has already been engulfed and the star is gigantic.
“What we missed was catching the star in the act, where you have a planet that suffers this fate in real time. That’s what makes this discovery so exciting.’
The research has been published in the journal Nature.