Several planetary systems across the galaxy have "super-Earths", which are rocky worlds slightly larger than our own planet. But our cosmic neighbourhood doesn't have a single one, leaving scientists wondering what the reason is. Now, a new study, published in Monthly Notices of the Royal Astronomical Society, suggests a dramatic reason behind it as the scientists believe the Sun might have eaten it.
For decades, astronomers studying the Sun's interior have run into puzzling dead ends. Theoretical computer models explaining how the Sun works never quite match real-world observations.
Specifically, scientists couldn't explain the exact depth of the Sun's churning outer layers, and more. They also explore how sound waves travel through its core, or why the Sun contains far less surface lithium than it should.
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According to research led by astronomer Mutlu Yildiz at Ege University in Turkey, adding a swallowed planet to the Sun's early history solves these mysteries all at once.
"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," DR Mutlu Yildiz, of Ege University, Turkey, said in a statement.
"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."
Using advanced computer simulations to model stellar evolution, the team found that a planet roughly five to ten times the mass of Earth falling into the young Sun billions of years ago fits the data better than any standard solar model.
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The study also noted that planets orbited inside a thick disk of gas and dust during the early days of the solar system. But that young super-Earth spirals inward toward the centre.
Researchers also found that such a world could survive its passage through the Sun's outer layers while losing very little mass, which suggests that planets may leave detectable fingerprints inside their host stars long after they have disappeared.
"We were interested in whether these problems might have a common origin in the early chemical history of the Sun," Professor Yildiz explained. "Young stars are surrounded by protoplanetary discs, where substantial amounts of material can move between the disc and 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."
