Scientists witness star swallowing planet, offering glimpse into Earth's final fate

Astronomers spotted a star becoming more than 100 times brighter in just 10 days before fading away. (Image: GeminiObservatory/Facebook)

Scientists have caught a rare glimpse of the end of the world by observing a star engulfing a nearby planet. The discovery was made by astronomers who spotted a star becoming more than 100 times brighter in just 10 days before fading away.

They later saw a colder, longer-lasting signal, which led to the conclusion that the star had engulfed a nearby hot Jupiter-sized planet, causing a white-hot flash followed by a colder, longer-lasting signal. This was recorded near the eagle-like constellation Aquila.

Researchers from MIT, Harvard University, and Caltech discovered the planet-eating star in May 2020, using the Zwicky Transient Facility (ZTF), but it took them another 12 months to piece together what was happening.

Scientists had previously observed stars just before and shortly after consuming entire planets, but had never caught one in the act until now.

The team estimated that since its initial outburst, the star had released a surprisingly small amount of energy, only about 1/1,000 the magnitude of any stellar merger previously observed. This led the team to realise that the bright, hot flash had likely been the final moments of a Jupiter-sized planet being pulled into a dying star's ballooning atmosphere.

The observation of the planet-eating star is a sobering glimpse at Earth's fate, which will occur when the sun runs out of fuel and becomes a white dwarf, engulfing the solar system's inner planets.

Although this will not happen for at least 5 billion years, the observation provides scientists with a unique opportunity to study the final moments of a planet's life. Lead author Kishalay De, of MIT's Kavli Institute for Astrophysics and Space Research, said, "We were seeing the end-stage of the swallowing. We are seeing the future of the Earth."

"Astronomers using the Gemini Observatory South telescope in Chile, operated by NOIRLab, have observed the first evidence of a dying Sun-like star engulfing an exoplanet. The “smoking gun” of this event was seen in a long and low-energy outburst from the star — the telltale signature of a planet skimming along a star’s surface. This never-before-seen process may herald the ultimate fate of Earth when our own Sun nears the end of its life in ~five billion years," Gemini Observatory wrote in a press release.

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The discovery provides new insights into the evolution of stars and planets. For decades, astronomers have been able to observe stars before and after engulfing planets but have not caught them in the act.

The latest discovery provides scientists with a rare opportunity to observe a planet undergoing this fate in real-time. De said, "What we were missing was catching the star in the act, where you have a planet undergoing this fate in real-time. That's what makes this discovery really exciting."