[The Epoch Times, November 23, 2023](Epoch Times reporter Chen Juncun reported) Scientists from the National Aeronautics and Space Administration (NASA) have discovered that some exoplanets seem to be “shrinking” and their mass is getting smaller and smaller. It may be caused by radiation emitted from the planet’s interior.
NASA points out that some exoplanets appear to be losing their atmospheres and shrinking. In a study using data from the agency’s retired Kepler space telescope, astronomers found that this may be because radiation from the planets’ cores pushes their atmospheres into space.
Planets outside our solar system are called exoplanets, and they come in many sizes, from small rocky planets to giant gas giants. In the middle are super-Earth (with a diameter of up to 1.6 times that of the Earth) and the larger sub-Neptune (with a diameter of 2 to 4 times that of the Earth).
NASA has discovered more than 5,000 exoplanets so far, but there are very few exoplanets with diameters between 1.5 and 2 times that of Earth. Scientists say they have enough data to prove that it is no coincidence that there are so few exoplanets of this size and mass, but that something prevents exoplanets from growing to this mass or maintaining this mass.
Researchers believe that there are not many exoplanets of this mass, possibly because some sub-Neptunes lost their atmospheres over time. If these planets don’t have enough mass, there won’t be enough gravity to support an atmosphere. As a result, these planets lose their atmosphere and shrink to the size of super-Earths, leaving many fewer planets in between.
Researchers have proposed two theories, one is the mass loss caused by the planet’s core, and the other is photoevaporation (which refers to the ionization of gas by high-energy radiation), and this study also found evidence to support the first theory. .
Jessie Christiansen, a scientist at the California Institute of Technology (Caltech) and NASA and the lead author of the study, said mass loss caused by the planet’s core refers to the radiation emitted by the planet’s hot core pushing the atmosphere away from the inside out. , resulting in a reduction in quality.
She said her research team has spent five years looking for exoplanets suitable for study, but the research is not over yet because people’s understanding of the two theories may change over time.
The Kepler Space Telescope used in this research ended its mission on October 30, 2018 after nine years of service. Scientists have used its data to discover more than 2,600 confirmed exoplanets, with thousands more possible exoplanets yet to be confirmed.
The above research results were published in the Astronomical Journal on November 15.
Editor in charge: Ye Ziwei#
