Ageing stars found to destroy nearby giant planets

Ageing stars found to destroy nearby giant planets
by Sophie Jenkins
London, UK (SPX) Nov 06, 2025

Astronomers from University College London and the University of Warwick have discovered that ageing stars may be responsible for destroying giant planets in close orbits. When stars similar to the Sun exhaust their hydrogen fuel, they expand and cool, entering the red giant phase. This transformation can lead to the engulfment and destruction of closely orbiting giant planets.

The research, published in Monthly Notices of the Royal Astronomical Society, examined nearly half a million stars in the early stages of post-main sequence evolution. Among these were 130 planet and planet candidates, 33 of which were identified for the first time. The study found significantly fewer close-orbit giant planets around stars that had expanded sufficiently to be classified as red giants, implying the destruction of planets in these systems.

Dr Edward Bryant from the Mullard Space Science Laboratory stated, "This is strong evidence that as stars evolve off their main sequence they can quickly cause planets to spiral into them and be destroyed. This has been the subject of debate and theory for some time but now we can see the impact of this directly and measure it at the level of a large population of stars."

He explained that this destruction likely results from growing tidal interactions between the planet and the star as it expands. These interactions cause planetary orbits to contract, leading to the planets either breaking apart or being engulfed.

Co-author Dr Vincent Van Eylen added, "In a few billion years, our own Sun will enlarge and become a red giant. When this happens, will the solar system planets survive? We are finding that in some cases planets do not."

Earth is likely safer than many of the giant planets identified in the study, as it lies farther from the Sun. However, the long-term prospects for habitability are not promising, according to the researchers.

The team used NASA's Transiting Exoplanet Survey Satellite (TESS) data and an algorithm to identify repeated brightness dips signaling a planet passing its host star. They focused on large planets with orbits of 12 days or less, narrowing over 15,000 candidate signals to 130 by rigorous exclusion of false positives.

The likelihood of finding a close-orbit giant planet was just 0.28% overall, dropping as low as 0.11% among the most evolved red giant stars - indicating that advanced stellar evolution substantially reduces planetary survival rates in these environments.

Researchers are working to confirm the planetary nature of all candidates by measuring their mass through detailed observations of host star movements. This ongoing research aims to clarify the cause of planetary destruction around dying stars.