2023-06-03 23:08:00
A study has found that regarding a third of exoplanets around dwarf stars, the most common type of exoplanets currently being discovered, are located in regions with liquid water where life might exist.
A team led by Professor Sarah Ballard of the University of Florida, USA, published in the scientific journal Proceedings of the National Academy of Sciences (PNAS), the latest astronomical telescope observation data, and as a result, one-third of exoplanets around red dwarfs, the most common type of stars, are in a liquid state. It is estimated that it is going around a ‘Goldilocks orbit’ where water can exist.
The most common type of star in our galaxy is the red dwarf star, which is regarding half the mass of the sun and much cooler. Billions of exoplanets are known to orbit these dwarf stars, and in fact many exoplanets are found around dwarf stars.
| ▲ Kepler Space Telescope and imagined exoplanets. |
The research team explains that for planets around dwarf stars to be warm enough for life to exist, their orbital orbit must be close to the star. did.
In this study, Professor Ballard and Sheila Sajier (doctoral student), who have long studied exoplanets, used exoplanet observation data from NASA’s Kepler Space Telescope and the Gaia Telescope, which measures distances to billions of stars in the Milky Way. analyzed the data.
Using the Kepler telescope, they calculated the eccentricity of the planet’s orbit by measuring the time it took for regarding 150 exoplanets around a dwarf star the size of Jupiter in our galaxy to move across the central star.
The research team said that the eccentricity is higher as the orbit is more elliptical, and the higher the eccentricity, the closer the exoplanet orbits to the star, so the tidal phenomenon caused by the strong gravity generates frictional heat, raising the temperature to the point where liquid water cannot exist.
As a result of the analysis, two-thirds of the 150 exoplanets around the dwarf star had very high orbital eccentricities, making it difficult for liquid water to exist due to tidal frictional heat caused by the star’s gravity.
However, the research team said that the remaining one-third of the exoplanets orbited in the ‘goldilocks’ region where liquid water might exist, and that there might be hundreds of millions of such exoplanets in our galaxy alone.
The Goldilocks area is a term derived from the girl Goldilocks in the traditional fairy tale ‘Goldilocks and the Three Bears’, who found porridge at a suitable temperature that was not too hot or too cold in a bear’s house. .
The research team also found that if there is one exoplanet around the star, the eccentricity of the orbit is high, so there is little possibility of life due to tidal phenomena, whereas if there are several planets attached to the star, there is a high possibility of rotating a circular orbit in which liquid water can exist. .
“These results show that dwarf stars are excellent targets in the search for exoplanets with liquid water,” said Sajer. said.
Science Team press@jeonpa.co.kr
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