Why our solar system missed out on having a super‑Earth, a type of world that teems across the galaxy, has long bugged astronomers.
Now, a new study proposes an intriguing explanation: maybe the sun ate it.
Mutlu Yildiz, an astronomy professor at Ege University in Turkey, used computer simulations to wind back the clock and study the young sun with and without a swallowed planet to see which version best matches the star we know today. His models that fed the sun a dense, rocky super‑Earth — about five to 10 times more massive than Earth and rich in heavy elements like Mercury — lined up closely with real measurements.
Earlier work has proposed that a super‑Earth could have formed and then spiraled through space into the sun billions of years ago, but this paper is perhaps the first to delve deeply into the idea, asking whether the sun retains evidence that such an event took place.
“We believe it could,” Yildiz said in a statement.
Lithium is one of the most important chemical clues pointing to a planet’s engulfment. When the sun formed, it was made from the same stuff as meteorites and the gas cloud around it. From those rocks and gases, scientists can estimate how much lithium the newborn sun should have had. Today, the sun’s surface has over 100 times less lithium than expected.
Lithium atoms only break apart deep inside a star, where it is much hotter, so the missing element hints that something might have dragged it down.
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An artist’s rendering of a super-Earth orbiting a sun-like star
Credit: NASA / JPL-Caltech illustration
The new study, published in Monthly Notices of the Royal Astronomical Society, suggests a scenario in which the ill‑fated planet brings in material that is poor in lithium but rich in heavier elements. Yildiz dubbed the hypothetical planet Dev Dilek, meaning “Great Wish” in Turkish. The name Dilek is traditionally associated with wishes directed toward Mercury, and the prefix “Dev” means giant.
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Mixing that lithium-poor material into the sun’s outer layers helps explain the lithium shortage. Meanwhile, the extra heavy elements buried just below the surface make the models of the sun’s interior — including how sound waves travel and how deep the churning outer layer goes — line up better with what astronomers actually observe.
The study also checks whether a rocky planet could realistically survive the plunge into the sun long enough to deliver its material to the right depth. Separate calculations track how a compact, iron‑rich world behaves as it falls through hot solar gas. Under intense pressure, the planet shrinks, exposing a smaller area to the gas and slowing the rate at which its outer layers burn off.
In the computer simulations, the planet loses only a fraction of its mass before reaching the base of the convection zone. That means most of its rocky core could end up exactly where the solar models need it, according to the research.
While Yildiz had a hunch that absorbing a planet could affect the sun’s structure, he didn’t expect the math to align so closely with a specific type of planet’s mass range.
“That was one of the most interesting outcomes,” he said.
Astronomers already have evidence that stars can eat their planets. Some stars briefly brighten and swell after swallowing nearby exoplanets, and subtle shifts in the orbits of hot Jupiters suggest that many are slowly falling inward toward their stars. Studies of sun-like stars also find chemical patterns that hint at past planet meals.
The new paper puts a mirror in front of our own star. Though it doesn’t prove the sun devoured a super‑Earth, it does show that a sun with an early planetary feast matches a wide range of measurements better than any model without it.
“The next step is to see if these fingerprints can be independently detected,” Yildiz said.
