“There may be hundreds of millions of exoplanets in our galaxy”

A study has found that about a third of exoplanets around dwarf stars, the most common type of exoplanet currently discovered, are located in regions with liquid water where life could exist.

A team led by Professor Sarah Ballard from 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 the exoplanets around red. a dwarf, the most common type of star, is in a liquid state. It was revealed that it is estimated to be orbiting a ‘Goldilocks’ orbit where water can exist.

The most common type of star in our galaxy is the dwarf star, which is about half the mass of the sun and much cooler. Billions of exoplanets are known to revolve around these dwarf stars, and in fact many exoplanets are found around small stars.

▲ The Kepler Space Telescope and imaginary 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 that made it.

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 measure distances to billions of stars in the Milky Way to analyze the data.

Using the Kepler telescope, they calculated the eccentricity of the planet’s orbit by measuring the time it took for around 150 exoplanets around a Jupiter-sized dwarf star 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 produces 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 a very high orbital eccentricity, making it difficult for liquid water to exist due to the tidal frictional heat caused by the gravity of the a star

However, the research team said that a third of the remaining exoplanets orbit in the ‘golden halo’ region where liquid water could exist, and that there could be hundreds of millions of such exoplanets in our galaxy in lonely

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 neither too hot nor too cold in a bear 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, but if there are several planets associated with the star, there is a high . possibility of circular orbit rotation where liquid water can exist. .

“These results show that dwarf stars are excellent targets in the search for exoplanets with liquid water,” said Sajer.

Science Team

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