IT之家 October 27 news, according to Xinhua Net, recently, the team of Professor Qian Shengbang from the School of Physics and Astronomy at Yunnan University published a paper in the international academic journal Proceedings of the National Academy of Sciences of the United States, reporting an observational result that challenges conventional understanding: three exoplanets orbiting stars have survived after their host stars entered late-life dramatic expansion.
According to IT之家, under the long-standing mainstream view, stars similar to the Sun shine and generate heat through core hydrogen fusion; when the hydrogen fuel nears exhaustion, the star rapidly expands into a red giant, with its volume able to increase by hundreds of thousands or even millions of times. At this point, planets that are too close usually cannot escape two outcomes: one is being directly engulfed by the expanding stellar atmosphere, and the other is gradually spiraling toward the star under tidal effects.
However, the research subjects of Qian Shengbang’s team fall precisely into the category of “should have been swallowed.” The team first used satellite observation data to capture subtle changes in the luminosity of the host stars of three exoplanets — 24 Boo, HD 12648, and TYC 4282-605-1 — and determined that these stars have entered the core helium burning stage. Subsequently, the researchers used stellar evolution models to trace back the past expansion range of the host stars and compared it with the current orbital positions of the planets. The results showed that the orbital scales of all three planets are in regions where they should theoretically have been engulfed, yet they still exist.
“In the past, if only a single surviving planet was found, it could still be explained as a chance event. But this time finding three ‘lucky ones’ at once shows that this is not an isolated case, and there may be some common physical mechanism behind it,” Qian Shengbang said in an interview. This result means that the academic judgment that “planets too close to stars are unlikely to survive the red giant expansion phase” needs to be re-examined, and the interaction between stars and planetary systems in their late years may be more complex than existing models suggest.
The discovery also evokes associations with the long-term evolution of the solar system. Qian Shengbang pointed out that in about several billion years, the Sun may also enter the red giant stage; traditional theory tends to believe that Earth cannot escape the fate of being engulfed by the expanding Sun, while the new evidence suggests that the future fate of the solar system, including Earth, may be more variable than theoretical predictions.
Yunnan University and the Yunnan Observatories of the Chinese Academy of Sciences and other institutions jointly participated in this research.