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Astronomers make rare discovery of star eating up planet

K. Miller/R. Hurt (Caltech/IPAC)

(PASADENA, Calf.) — A Jupiter-sized planet was the main course for a dying star’s meal, according to scientists who witnessed this rare interstellar course.


A study published Wednesday in “Nature,” detailed the observations and analysis of the event that took place on May 20, 2020. Kishalay De, a postdoc at MIT’s Kavli Institute for Astrophysics and Space Research, and the lead author of the study, said the gaseous planet spiraled close into the star’s orbit until it was engulfed into its core.

De said the event created an outburst that made the star 100 times brighter over just 10 days, before quickly fading away.

“We were seeing the end-stage of the swallowing,” he said in a statement.

De and his team discovered the event through Zwicky Transient Facility (ZTF) at Caltech’s Palomar Observatory in California, which scans the sky for stars that rapidly change in brightness.

It took another year for De and his team to determine what caused the change in brightness that was observed. He analyzed data from the Keck Observatory in Hawaii, which also observed the event.

De said that the data from Keck puzzled him, as it showed that the two objects didn’t give off hydrogen and helium, which is what typically happens when a dying star erodes another.

The team got more data from the Palomar Observatory which used an infrared camera to observe the event and it showed “signals of colder material, in contrast to the white-hot, optical emissions that arise from binaries and other extreme stellar events.”

“That infrared data made me fall off my chair,” De said. “The source was insanely bright in the near-infrared.”

More data found that the dying star threw out colder energy for over a year. De said the data showed that the energy was about 1000 times smaller than the star, which was a key breakthrough.

“And it’s a happy coincidence that the mass of Jupiter is about 1/1,000 the mass of the sun. That’s when we realized: This was a planet, crashing into its star,” he said.

De said the observation is very significant because such an event has never been seen in real-time.

He also said that a similar event is predicted to happen to Earth, but not for another 5 billion years, after the sun burns out.

“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,” De said.

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