2023-06-06 20:00:00
Our Sun, a warm star spectral type G2 and luminosity V which is classified in the group of calls yellow dwarfs it is, relatively speaking, a rarity in the Milky Way. In fact, the most common stars in our galaxy are considerably smaller and cooler, barely half the mass of the Sun. Billions of planets orbit these small stars common in our galaxy: brown dwarfs.
In general, the total radiation emitted by a brown dwarf is much less than the total radiation emitted by the Sun, so pto capture enough heat To be habitable, planets in the orbit of a brown dwarf would have to be very close to their star.something that, on the other hand, would leave them exposed to the extreme tidal forces generated by it.
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Now, after a new analysis based on the latest data from NASA’s Kepler telescope, a team of astronomers from the University of Florida has discovered that two-thirds of the planets located around these brown dwarfs could be swept away by these extreme tidal forces. , generating enough friction and heat to sterilize them completely. However, that means a third of these planets, hundreds of millions across the galaxy, could be located in the habitable zone of their star, that is, in that propitious to house liquid water and therefore also life.
Sarah Ballard y Sheila Sagearresearchers in the Department of Astronomy at the University of Florida, have long studied these exoplanets that orbit stars other than the Sun. “I think this result is really important for the next decade of exoplanet research, because eyes are turning to this population of stars,” explains Sagear. “These stars are excellent targets for looking for small planets in an orbit where it is conceivable that water is liquid and therefore the planet is habitable,” she adds.
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To reach this conclusion, Sagear and Ballard measured the eccentricity of a sample of more than 150 Jupiter-sized planets orbiting brown dwarf stars. The researchers found that if a planet orbits close enough to its star, roughly the distance that Mercury orbits the Sun, an eccentric orbit can subject it to a process known as tidal heating. As the planet is stretched and deformed by varying forces of gravity along its irregular orbit, it is heated by friction, something that it could “bake” the planet, eliminating all possibility of liquid water.
“Distance is really the key piece of information that we were missing that allows us to do this analysis,” says Sagear, who further states that stars with multiple planets are most likely to have circular orbits that they would allow them to retain liquid water, and that stars with only one planet were the most likely to experience tidal forces that would make them uninhabitable.
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Since a third of the planets in this small sample had orbits smooth enough to potentially host liquid water, that probably means the Milky Way has hundreds of millions of promising targets to search for signs of life outside our solar system.
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