Chinese Astronomers Discover Three Planets That “Should Not Exist,” Challenging Traditional Stellar Evolution Models

Chinese astronomers have reported a discovery that could deepen understanding of how planetary systems evolve as their host stars age. A research team led by Professor Qian Shengbang of Yunnan University has identified three exoplanets that appear to have survived the dramatic expansion of their host stars, despite occupying orbits that existing models suggest should have exposed them to engulfment.

According to Xinhua’s report on October 26, 2026, the team’s findings were published in the Proceedings of the National Academy of Sciences, or PNAS. The three host stars are known as 24 Boo, HD 12648 and TYC 4282-605-1. Although stellar evolution models indicate that these stars expanded to sizes that could have swallowed nearby planets, observations show that the planets remain in orbit.

The interaction between stars and their planets is a central topic in astronomy. Sun-like stars gradually exhaust the hydrogen fuel in their cores and eventually enter a red giant phase, during which their outer layers expand dramatically. Planets orbiting too close to such stars can face two possible fates: they may be engulfed directly by the expanding stellar atmosphere or gradually pulled inward by tidal forces until they are destroyed.

To investigate the three systems, the researchers analyzed subtle changes in the brightness of the host stars using satellite observations, including data from the Transiting Exoplanet Survey Satellite. Through asteroseismology—the study of oscillations within stars—they determined that the stars had passed through their red giant expansion phase and entered a stage in which helium is burning in their cores.

The team then used stellar evolution models to reconstruct the stars’ past expansion and compare the results with the planets’ current orbital distances. The analysis indicated that all three planets occupy orbital regions that theory suggests could have been engulfed by their host stars. Their continued existence therefore presents a challenge to straightforward predictions about the survival of close-in planets.

Finding three such planets is particularly significant because it may point to a shared physical process rather than an isolated exception. The researchers have proposed possible explanations, including past interactions or mergers involving binary stars, as well as changes in planetary orbits following the engulfment of inner planets. These scenarios remain hypotheses requiring further investigation.

The findings have also prompted discussion about the distant future of our own solar system. Scientists expect the Sun to become a red giant billions of years from now, expanding substantially as it evolves. Traditional models suggest that Earth could eventually be engulfed, but the newly identified systems indicate that the evolution of stars and their planets may be more complicated than simplified models predict.

The discovery does not establish that Earth will survive the Sun’s expansion, nor does it overturn the fundamental theory of stellar evolution. Instead, it reveals additional cases that current models must explain and provides new observational evidence for improving predictions about the long-term fate of planetary systems.

Researchers from Yunnan University and the Yunnan Observatories of the Chinese Academy of Sciences participated in the work. Further observations and theoretical studies will be needed to determine how the three planets survived and whether similar mechanisms operate in other systems around aging stars.