Super-Earth: For decades, astronomers have wondered why the solar system looks so different from many planetary systems found elsewhere in the galaxy. Super-Earths, worlds larger than Earth but smaller than Neptune, appear frequently around other stars, yet none exists in our solar system. NASA describes super-Earths as planets that can be up to about 10 times Earth’s mass, and they can be rocky, gaseous or a mixture of both.
Now, a new study offers an extraordinary explanation. The young Sun may have swallowed one.
Researchers led by Professor Mutlu Yildiz of Ege University in Turkey used stellar-evolution models to investigate whether consuming a planet early in the Sun’s history could explain some of the differences between what scientists expect the Sun’s interior to look like and what observations actually show.
The results point towards a possible planetary victim weighing between five and 10 times the mass of Earth. The researchers say material from such a world could have left chemical and structural traces inside the Sun that remain detectable today.
Super-Earth: Did The Sun Really Eat A Super-Earth?
The researchers are not claiming to have found direct proof of a swallowed planet.
Instead, their computer models show that a planetary-engulfment scenario can reproduce several properties of the present-day Sun more successfully than standard models in some respects. The study, published in the Monthly Notices of the Royal Astronomical Society, examines whether the Sun could still carry evidence of such an ancient event.
“Our new study suggests that a planet several times more massive than Earth may have fallen into the young Sun and left a lasting chemical imprint deep inside it,” Mutlu Yildiz, of Ege University in Turkey, said in a statement.
The idea builds on earlier research suggesting that a super-Earth could have formed close to the young Sun and then moved inward through the protoplanetary disc before eventually falling into the star.
The new work takes that idea further by asking a different question: if such a planet really disappeared into the Sun, could scientists still find its fingerprints billions of years later?
The researchers believe the answer may be yes.
Why is the Solar System Missing A Super-Earth?
Super-Earths are among the most common types of exoplanets discovered outside our solar system. Yet the planets orbiting the Sun follow a different pattern.
The inner solar system contains Mercury, Venus, Earth and Mars, while the larger planets farther out are gas or ice giants. There is no known planet between Earth and Neptune in size or mass that fits the usual definition of a super-Earth.
That difference has led astronomers to consider several explanations.
One possibility is that a super-Earth never formed here. Another suggests that one could have formed near the Sun but later migrated inward and disappeared.
Previous studies have proposed that a large rocky planet may once have occupied the region around the orbit of Mercury. If its orbit became unstable while the solar system was still forming, the planet could have moved towards the young Sun.
Yildiz and his colleagues have now tested what such an event could have done to the star itself.
Super-Earth: What is Dev Dilek?
The researchers gave their hypothetical planet the name Dev Dilek.
In Turkish, “Dev” means giant, while “Dilek” is associated with wishes directed towards Mercury. The name reflects the researchers’ proposed connection between the vanished planet and the region around the innermost part of the young solar system.
The model favours a planet several times heavier than Earth and rich in heavy elements. Some calculations point to a particularly good fit around 5.6 Earth masses, while the broader modelling favours a range of roughly five to 10 Earth masses.
That would put the proposed world firmly in the super-Earth category.
Super-Earth: The Lithium Mystery Inside The Sun
One of the most interesting clues comes from lithium.
The Sun contains much less lithium at its surface than scientists would expect based on the material from which it formed. Lithium is destroyed at high temperatures inside stars, so researchers have long studied the element as a clue to the Sun’s early history.
The planetary-engulfment model provides one possible explanation.
If the young Sun swallowed a planet whose material contained relatively little lithium but a larger amount of heavier elements, that material could have mixed into the star’s outer layers.
According to the researchers, this could help explain the unusually low amount of lithium observed at the Sun’s surface.
A Planet Could Have Left More Than Chemical Evidence
The proposed impact may have affected more than the Sun’s chemistry.
The researchers also examined the Sun’s internal structure. Their models suggest that material from an engulfed rocky planet could have settled below the Sun’s convection zone.
That matters because scientists use observations of solar oscillations and sound waves to study the star’s interior. The new models suggest that adding planetary material could improve the match between these observations and theoretical solar models.
The study specifically examines differences involving the depth of the Sun’s convection zone and its sound-speed structure.
“By modelling the sun’s evolution and comparing the results with precise observations of its interior, we find that the ingestion of a super-Earth could help explain long-standing differences between standard solar models and observations, including subtle changes in the sun’s internal structure and its depleted lithium abundance,” Yildiz said. “We were interested in whether these problems might have a common origin in the early chemical history of the sun.”
Could A Planet Survive Falling Into The Sun?
A major question is whether a rocky planet could survive long enough during its plunge to deliver material deep into the Sun.
The researchers therefore modelled the behaviour of a compact, iron-rich planet moving through the young Sun’s extremely hot and dense environment.
The calculations suggest that intense pressure could compress the planet as it travelled inward. As the world became smaller, it would expose less surface area to the surrounding gas, reducing the rate at which its outer material was stripped away.
That means a significant portion of the planet could potentially reach the region below the convection zone before being destroyed.
The result gives the planetary-engulfment scenario greater physical plausibility, although it does not establish that such an event actually happened.
How Could The Sun Have Swallowed The Planet?
The proposed event would have taken place when the solar system was still young.
At that stage, the Sun was surrounded by a broad protoplanetary disc made of gas and dust. Planets formed from material inside this disc, and their orbits could change as they interacted with the surrounding material and other growing worlds.
A sufficiently massive rocky planet could have gradually migrated inward.
Yildiz explained that young stars interact continuously with their surrounding discs, creating the possibility that planetary material could eventually reach the star.
“Since planets are made of material that is chemically different from the gas in the disc, we wondered whether the early engulfment of a planet could have left a chemical signature inside the young sun,” Yildiz said.
Scientists Did Not Expect Such A Specific Planet Mass
One of the researchers’ more surprising findings was how closely their calculations converged on a particular range of planetary masses.
The models did not simply suggest that swallowing any planet could solve the solar-model problems. Instead, the best results came from a relatively narrow range corresponding to a super-Earth.
“We thought planetary engulfment might affect the solar structure but did not expect the calculations to converge on such a specific super-Earth mass range,” said Professor Yildiz. “That was one of the most interesting outcomes of the study.”
This result is particularly interesting because it connects two separate puzzles — the missing super-Earth and the differences between solar observations and standard models.
Do Other Stars Eat Their Planets?
The idea of a star consuming one of its planets is not science fiction.
Astronomers have found evidence that planetary engulfment can occur in other systems. Researchers have also studied stars whose chemical compositions may carry signs of material from planets or smaller rocky bodies. The Royal Astronomical Society has highlighted evidence of stars swallowing Earth-sized worlds as part of broader research into stellar and planetary evolution.
That makes the idea of the young Sun consuming a planet physically possible.
The challenge is determining whether it actually happened here.
Can Scientists Prove The Sun Ate A Planet?
Not yet.
The current evidence comes from computer modelling and observations of the Sun’s internal properties, rather than a direct detection of planetary remains.
The researchers say the next stage will involve looking for independent fingerprints that could confirm or reject the scenario.
Earlier work had already suggested that a super-Earth might have formed close to the Sun and later migrated inward. The new study focuses on whether traces of such a planet could still exist inside the star today.
“The earlier work proposed that a super-Earth could have formed and migrated into the young sun. Our paper asks whether the sun itself could still carry observable evidence that such an engulfment actually happened, and we believe it could,” Yildiz concluded. “The next step is to see if these fingerprints can be independently detected.”
For now, Dev Dilek remains a hypothetical world. But if future observations uncover the predicted chemical or structural signatures, astronomers could gain a remarkable new window into the violent early history of our solar system.
