Star eats planet: Astronomers make unprecedented find in deep space

Astronomers know the fate of planets like Mercury, Venus, and Earth when their host stars are about to die, but they’ve never observed it happen in space — until now.

With the Gemini South Telescope(opens in a new tab) In Chile, scientists have seen the first evidence of a bloated old star absorbing an exoplanet as it puffs up during its final death throes. The event was observed in a long, low-energy burst – the sign that a planet is skimming the surface of a star.

In the past, astronomers have found evidence of stars that have been devouring planets, sometimes through some sort of autopsy of the dead star’s remains. But new research(opens in a new tab) published in the journal Nature presents the first direct evidence that Star Eats Planet happened. The group hopes the event will provide helpful clues for other researchers to discover other stars consuming planets elsewhere in the universe.

“Our interpretation … provides evidence for a missing link in our understanding of the evolution and ultimate fate of planetary systems,” the study’s authors wrote(opens in a new tab).

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During the event, about 12,000 light-years from Earth toward the constellation Aquila, the dying star, about the size of the Sun, absorbed a planet 10 times the mass of Jupiter, according to the study.

“Our interpretation…provides evidence for a missing link in our understanding of the evolution and ultimate fate of planetary systems.”

Unlike giant stars, which explode in a supernova and collapse into a black hole, a medium-sized star like the Sun meets a more agonizing end by slowly dying. A so-called “planetary nebula” — a confusing misnomer because stars cause it, not planets — is a phenomenon composed of the molten layers of an older star. Such spectacular clouds of gas and dust(opens in a new tab) occur when a star withers away from losing nuclear fuel.

What remains of the star’s core cools. Then the light goes out.

Do stars eat planets?

“For decades, we’ve been able to see the before and after,” Kishalay De, an MIT researcher and lead author, said in a university press release(opens in a new tab). “Before, when the planets are still very close to their star, and after, when a planet has already been engulfed and the star is huge. What we were missing was catching the star in the act, where you go through a planet that fate in real time. That is what makes this discovery so exciting.”

Scientists say they’ve finally caught a star devouring a planet in the final stages of its life.
Photo credit: K. Miller / R. Hurt (Caltech / IPAC) Figure

Astronomers expect this to be the future of the Sun in about 5 billion years.

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Watching a single star go through its entire life cycle would be impossible for obvious reasons: it would take billions of years, said Paul Sutter, a professor at Stony Brook University and author of How to die in space, in an interview with Mashable last year. But experts have been able to predict such a grotesque end for a planet by studying many stars at different distances and how they interact with their surroundings as they age.

“It’s like taking a snapshot of everyone on earth in one moment. You can’t capture a person’s life, but you can see people being born, you can see people playing football in elementary school and you can see people getting married. You see people dying, getting sick,” says Sutter, who was not involved in the new study. “You can reconstruct a human life cycle by putting all these pieces together, so we have a general picture of how stars evolve and how they live.”

Will the sun eat the earth?

There is evidence that when the Sun eventually undergoes this slow set, Earth will likely meet the same fate as the planet observed by the research group.

“We’re not exactly sure how big the sun will get — there’s a bit of uncertainty that it’ll either completely engulf the Earth or just reach the edge of our orbit,” Sutter previously said. “It would burn the earth anyway.”

Infographic on a star devouring a planet.
Photo credit: International Gemini Observatory / NOIRLab / NSF / AURA / P. Marenfeld

The new study confirms that as a Sun-like star nears the end of its life, it expands into a red giant that reaches 100 to 1,000 times its original size, eventually overtaking nearby planets. Such events are considered rare, occurring only a few times a year across the galaxy.

The eruption caused by the star engulfing the planet lasted about 100 days, according to the study.

“I think there’s something quite remarkable about these results that speaks to the evanescence of our existence,” Ryan Lau, a NOIRLab astronomer and co-author, said in a statement(opens in a new tab). “After the billions of years that comprise the lifespan of our solar system, our own terminal stages will likely end in a final flash lasting only a few months.”