Sun May Retain Clues of Engulfed Planet

Scientists now argue that the Sun’s early history may bear the fingerprints of a swallowed super‑Earth, offering a new way to probe the star’s formative years. The hypothesis, long suggested by the Sun’s anomalous metallicity and the absence of close‑in rocky planets, has been sharpened by a recent study that models how a planet of several Earth masses would alter the Sun’s internal structure. The research team claims that the engulfment would leave measurable traces—such as subtle shifts in the sound‑speed profile and changes in the distribution of heavy elements—that could still be detected with today’s helioseismic data.

Using data from the Solar and Heliospheric Observatory and the Global Oscillation Network Group, the authors compared the Sun’s observed oscillation frequencies with models that include a past planetary ingestion event. They found that a planet with a mass between five and ten Earth masses, accreted when the Sun was still a pre‑main‑sequence star, would produce a distinct signature in the depth of the convection zone and in the gradient of metallicity just below it. The study’s simulations suggest that these signatures are within the sensitivity limits of current instruments, implying that the Sun’s interior could still carry the chemical imprint of a swallowed planet.

If confirmed, the findings would provide the first direct evidence of early planetary migration and consumption in a Sun‑like star, offering a new tool for studying the evolution of planetary systems. The research also highlights the importance of precise helioseismic measurements in uncovering the Sun’s hidden history, potentially guiding future observations aimed at detecting similar events in other stars.