Mutlu Yildiz said a new super-Earth model suggests the young Sun may have swallowed a planet 5 to 10 times Earth’s mass billions of years ago. The study says that event could have left a lasting chemical imprint deep inside the Sun and may help explain its low lithium content.
Yildiz, an astronomer at Ege University in Turkey, said, "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." He also said, "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."
Monthly Notices of the Royal Astronomical Society
The study appeared in Monthly Notices of the Royal Astronomical Society and used an open-source module to map stellar evolution across a wide range of theories. The best-fitting model included the Sun’s consumption of a super-Earth-mass planet billions of years ago, and the calculations matched known measurements of the Sun’s interior and lithium content.
Yildiz said, "We were interested [in] whether these problems might have a common origin in the early chemical history of the Sun." He added, "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."
Sun and lithium
The study points to two features that did not fit conventional solar models: the Sun’s surface has a notable deficiency of lithium compared with similarly sized stars, and those models had trouble replicating observations of the solar convection zone. In the paper’s account, the swallowed-planet scenario offers a single origin for both mismatches.
The calculations strengthen the physical plausibility that the Sun swallowed a super-Earth planet, but the paper does not say that the event happened. Yildiz said, "Our paper asks whether the Sun itself could still carry observable evidence that such an engulfment actually happened, and we believe it could."
Ege University study
Yildiz said, "The next step is to see if these fingerprints can be independently detected." For readers, that makes the study a testable proposal rather than a closed case: the Sun’s chemistry may still hold the signal, and future work will have to find it.
