A team of astronomers has found strong evidence that a star similar to our sun may have eaten one of its own planets.
The star, known as TOI-5882, is located about 1,300 light-years from Earth.
Researchers discovered that it contains an unusually high amount of lithium, a chemical element that may reveal a dramatic event in the star’s history.
“You are what you eat” is an idea that also seems to apply to stars. While stars naturally contain a small amount of lithium, planets are much richer in this element.
If a star swallows a planet, it can absorb a large dose of lithium, leaving behind a chemical fingerprint.
Astronomers call this process “planetary engulfment.” Surprisingly, the event itself happens very quickly on cosmic timescales, taking only days or weeks.
Because of this, scientists almost never get the chance to witness a star consuming a planet in real time. Instead, they have to work like detectives, searching for clues that remain long after the event has occurred.
Lead author Brooke Kotten from the University of Michigan says this detective work is what makes the field so exciting.
Since researchers cannot observe the “crime” directly, they have to piece together the evidence to determine what happened.
Studying these events helps scientists understand how often stars swallow planets and the different ways it can happen.
Our own solar system may experience something similar in the distant future. In about five billion years, the sun is expected to expand into a red giant, becoming so large that it will likely engulf Mercury and Venus and may even consume Earth.
However, TOI-5882 has not yet expanded enough for this explanation to work. Instead, the researchers suspect another object may have played a role.
Orbiting the star is a massive brown dwarf, an object that is larger than planets but too small to become a true star. It has more than 20 times the mass of Jupiter. Scientists think this brown dwarf may have disturbed the orbit of a nearby planet, eventually pushing it into the star.
The researchers estimate that the swallowed planet probably had a mass somewhere between a few Earths and Neptune.
To make their discovery, the team used a technique called spectroscopy, which studies the light coming from stars. Different chemical elements leave distinctive patterns in starlight, allowing scientists to identify them from great distances.
To confirm that TOI-5882’s lithium level was truly unusual, the team compared it with 62 similar stars that matched its age, size, and temperature. No matter how they analyzed the data, TOI-5882 stood out. It contained more lithium than at least 97% of the comparison stars.
Interestingly, a few of the other stars also showed elevated lithium levels, hinting that there may be additional ways for stars to become enriched with this element. For astronomers, that means one mystery has been solved, but several new ones have just begun.
Source: University of Michigan.
