An astronomer sees a star “eat” a planet for the first time

An astronomer sees a star "eat" a planet for the first time

12,000 light-years from Earth, astronomers have discovered a dying star swallowing a planet. This is a first. Although the idea of ​​some dying stars “devouring” their planets has been around for a long time, the event has now been observed for the first time. MIT astronomer Kechalay D and colleagues participated their results Wed in the journal nature.

In the distant future, Earth and many other planets are also likely to burn up and be swallowed up by their stars.

How does that happen? Nuclear fusion reactions occur spontaneously under extreme pressure and temperature inside the star. The stars get their fuel from that. When the stars run out of energy, the star can no longer provide enough anti-gravity pressure and collapses. In stars of similar size to the Sun, the pressure and temperature rise so high that nuclear fusion can occur again. As a result, the star swells to hundreds of times its original size. At that point, astronomers call the star a red giant. When a red giant’s beam approaches a planet, that planet is incinerated and engulfed in a matter of weeks.

Difficulty perceiving

Ignas Snellen, an astronomer at Leiden University who was not involved in the study: “We already knew that this often happens, because there are many worlds whose orbit around their star is within the radius of the future red giant. But it is difficult to realize this. It takes thousands of years for a star to grow , while such a star would swallow a planet in a few weeks. So you would have to scan a very large part of the sky to have such a flash somewhere.”

Read also: The black hole eats the neutron star

This survey of a large part of the sky is exactly what astronomer D. He analyzed measurement data from the Zwicky Transient Facility (ZTF) telescope in California in the spring of 2020. In fact, he was looking for signals from merging stars. When a star swallows another star, the star temporarily becomes about a thousand times brighter, and is seen as a twinkle. Among the dates, he found a flash of a star that was “only” a hundred times brighter. Snellen: “The thing that got swallowed must be smaller than a star.”

Relatively cool

Di and his colleagues analyzed the dust surrounding the star, which was relatively cool. ZTF sees in the same light that human eyes perceive, but cooler objects in the universe are much brighter in infrared light. They studied the flash in infrared observations from the Keck Observatory in Hawaii, Palomar Observatory and NASA’s NEOWISE infrared space telescope.

Various observational accounts show that the flash was caused by a sun-like star engulfing a planet ten times the size of Jupiter.

Astronomers estimate that the Sun is only in the middle of its life

“A very good result,” Snellen replies. “The fact that this has now been detected shows that astronomical observations are getting better and better. I expect other sightings of planet-swallowing stars soon.”

Astronomers estimate that the Sun is only in the middle of its life. This means that it will take another five billion years for it to swell into a red giant. Mercury, Venus, and possibly Earth will not survive it. “But it wouldn’t be noticeable out in the universe,” Morgan MacLeod says at a news conference. He is a Harvard astronomer and co-author of the study. When a star “eats” a large planet, as has now been observed, it produces a bright flash. Earth is about 300 times lighter than Jupiter. “When our sun engulfs the smaller planets in the solar system, it’s less dramatic.”

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