Sun May Have Swallowed a Super-Earth, Study Says

New modelling suggests the young Sun devoured a rocky super-Earth of five to ten Earth masses, leaving chemical and seismic fingerprints that may still be detectable today.

A new study published September 10 in Monthly Notices of the Royal Astronomical Society proposes that the young Sun swallowed a super-Earth billions of years ago. Mutlu Yildiz of Ege University in Turkey used stellar-evolution models to test whether ingesting a planet several times more massive than Earth could explain long-standing differences between standard solar models and observations. The best-fitting scenario involves a rocky, heavy-element-rich planet of five to ten Earth masses that spiralled inward through the protoplanetary disc and fell into the star, leaving a lasting chemical imprint deep inside it.

Super-Earths — worlds larger than Earth but smaller than Neptune — are among the most common exoplanets discovered, yet our solar system has none. The idea that the Sun may have eaten its missing super-Earth is a dramatic answer to that puzzle. Yildiz reportedly did not expect the calculations to converge on such a specific super-Earth mass range, calling that one of the most interesting outcomes of the study, according to space.com. The hypothetical planet was informally named Dev Dilek, meaning "Great Wish" in Turkish, per Mashable SEA.

The Sun's surface has over 100 times less lithium than expected, and because lithium only breaks apart deep inside a star, its absence hints that something may have dragged it down, Mashable SEA reports. The engulfment model suggests the planet delivered lithium-poor, heavy-element-rich material that helps explain the depletion. The scenario also improves the match between helioseismic measurements — how sound waves travel through the solar interior — and the observed depth of the Sun's convection zone, according to SpaceDaily. The dissolved planetary material would have settled below the convection zone, creating a localized heavy-element enhancement.

A key question is whether a rocky world could survive falling into the Sun long enough to deliver material to the required depth. According to SpaceDaily, Yildiz's feasibility calculations suggest that a compact, iron-rich planet would be compressed under intense pressure, shrinking its cross-section and slowing drag and ablation, so that most of its rocky core could reach the base of the convection zone. The outlet cautions this is a plausibility result, not a simulated ingestion, with orbital dynamics and hydrodynamic instabilities left for future work.

If confirmed, the finding would simultaneously solve two puzzles: the missing super-Earth in our solar system and persistent mismatches between solar observations and standard models. Astronomers already have evidence that stars eat their planets — some brighten after swallowing exoplanets and chemical patterns in sun-like stars hint at past meals, per Mashable SEA. Earlier work by Rebecca Martin and Mario Livio in 2016 had proposed a pathway for inward-migrating super-Earths falling into the young Sun, and the new paper asks whether the Sun itself retains an observable record of such an event, SpaceDaily reports.

The researchers stress this is a possibility built on computer modelling, not proof the Sun devoured a planet. No buried planet has been detected, and the model does not require the planet to have been totally engulfed, notes space.com. The decisive test would be independently identifying the predicted composition gradient and sound-speed structure and showing ordinary adjustments to opacity and mixing cannot reproduce them, according to SpaceDaily. "The next step is to see if these fingerprints can be independently detected," Yildiz said. Solar neutrinos, improved abundance measurements and asteroseismology of other stars may add cross-checks.