In a rare and spectacular event, astronomers have witnessed a star devouring a planet for the first time. The cosmic drama occurred in our own galaxy, about 12,000 light-years away, near the Aquila constellation.
The star, ZTF J2019+2456, is a red giant that has expanded to a million times its original size as it runs out of fuel. As it grows, it engulfs any nearby objects, including planets and moons. This process produces a bright flash of light, followed by a colder and longer-lasting signal, as the star spits out some of the material it swallowed.
The astronomers detected this unusual signal in May 2020, using data from the Zwicky Transient Facility (ZTF) at the Palomar Observatory in California. They confirmed their observations with data from other telescopes, including NASA’s NEOWISE infrared space telescope.
The planet consumed by the star was about the size of Jupiter, according to the researchers. They estimate that it orbited the star at about 0.1 astronomical units (AU), or one-tenth of the distance between Earth and the Sun. For comparison, Mercury orbits the Sun at about 0.4 AU.
The researchers say that this event is a glimpse of what will happen to Earth in about five billion years, when our Sun will become a red giant and engulf the inner planets of our solar system.
“We are seeing the future of the Earth,” said Kishalay De, a postdoctoral researcher at MIT and the lead author of the study published in Nature. “If some other civilization was observing us from 10,000 light-years away while the Sun was engulfing the Earth, they would see the Sun suddenly brighten as it ejects some material, then form dust around it, before settling back to what it was.”
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