Astronomers proposing a new solar evolution model suggest the Sun may have swallowed a super-Earth planet five to 10 times more massive than Earth during its early history, leaving chemical clues deep inside our star that could explain its mysterious lithium depletion and internal structure.
Why our solar system lacks a super-Earth—a planet type that teems across other star systems—has long puzzled astronomers. A new study published in the journal Monthly Notices of the Royal Astronomical Society offers a striking solution: maybe the sun ate it.
Researchers used advanced stellar evolution software and computer simulations to wind back the clock on our solar system. The modeling explored whether the young Sun could have devoured a massive, rocky planet billions of years ago during its infancy, and whether our star might still conceal the chemical and structural fingerprints of that violent event today.
Mutlu Yildiz and Ege University Computer Simulations
The research was led by Mutlu Yildiz, an astronomy professor and researcher at Ege University in Turkey. Yildiz tested computer simulations of the young Sun with and without an engulfed planet to determine which scenario aligns most closely with precise observations of the star we observe today.
The models that fed the Sun a dense, rocky super-Earth ranging from five to 10 times more massive than Earth lined up significantly better with real-world measurements than standard solar models that omit planetary engulfment.
Solving the Sun Lithium Mystery and Structural Discrepancies
For years, astronomers have wrestled with subtle discrepancies between standard solar models and observations. These include the precise depth of the Sun’s convection zone, the speed sound waves travel just below that churning outer layer, and a severe shortage of lithium.
When the Sun formed, it coalesced from the same primordial gas cloud and meteorites as the rest of the solar system, giving scientists a baseline for how much lithium the newborn star should contain. Today, the sun’s surface has over 100 times less lithium than expected. Because lithium atoms break apart only under extreme heat deep inside a star, the missing element indicates an unknown mixing mechanism dragged it downward.
The hypothesis suggests that the infalling planet delivered material rich in heavy elements but poor in lithium. Yildiz dubbed the hypothetical world Dev Dilek, combining the Turkish prefix meaning giant with Dilek, a traditional name associated with wishes directed toward Mercury.
Planetary Survival During the Solar Plunge
A central question for researchers was whether a rocky world could survive the intense heat and pressure long enough to deposit its heavy elements at the correct depth within the young Sun. Separate calculations tracked how a compact, iron-rich body behaves as it falls through hot solar gas.
Under extreme pressure, the planet shrinks in size, exposing a smaller surface area to the surrounding gas and slowing the rate at which its outer layers burn off. Simulations showed that the planet loses only a fraction of its mass before reaching the base of the convection zone, allowing its dense rocky core to deliver material exactly where solar models require it.
Previous studies suggested that one or more super-Earth planets could have formed within the orbit of Mercury before migrating inward through the protoplanetary disk surrounding the infant Sun. While stars eating exoplanets is an observed phenomenon in distant star systems—marked by temporary brightening and shifting orbits of hot Jupiters—this study turns the inquiry inward.
The research was published in Monthly Notices of the Royal Astronomical Society. Researchers emphasize that while computer modeling cannot definitively prove the event occurred, a sun with an early planetary feast matches observations more closely than any model without one.
Related reading