Monitoring an exoplanet dangerously close to its star… a glimpse of the end of Earth?

Astronomers have discovered for the first time a distant planet that is dangerously close to its aging star, according to a study published Monday, the results of which give an idea of ​​the possible end of planet Earth. Located 2,600 light-years from Earth, Kepler-1658b is an exoplanet about the size of Jupiter.

But unlike this gas giant far from the sun, Kepler orbits only around its star, an eighth of the distance separating our sun from Mercury, the planet closest to it.

The study, published by The Astrophysical Journal Letters, indicated that this “hot buyer” orbits its star in less than three days, and this rotation period shrinks by about 131 milliseconds per year.

“At this rate, the planet will collide with its star in less than three million years,” said lead author Shreyas Visapragada of the Harvard-Smithsonian Center for Astrophysics.

“This is the first time that we have observed direct evidence of a planet moving, with a spiral path around its aging star,” the astrophysicist told AFP. The star in question is in an advanced stage of its cycle, when it begins to swell and become brighter.

Kepler’s orbit shrinks inexorably under the influence of gravity exerted by the star, similar to the gravity exerted by the Moon on various points on Earth. This effect called tidal force can attract two bodies just as it can move them away from each other, for example the moon is moving very slowly away from the earth in a spiral path.

Earth’s last farewell?

Will our planet experience the same process of disintegration? “The death of a planet due to a star is a fate that awaits many worlds: it could spell Earth’s final farewell after billions of years as it continues to orbit the sun,” the Center for Astrophysics wrote in a statement. In five billion years, the sun will become a “red giant” that will grow exponentially, much like Kepler’s host star.

Like this exoplanet, Earth can inexorably draw closer to the sun under the influence of tidal forces. But this effect can also be offset by the loss of mass from the Sun, says Shreyas Visapragadhan, who stresses that “the ultimate fate of the Earth is still not clear.”

Kepler was the first exoplanet to be detected by the Kepler space telescope, in 2009. For 13 years, scientists have been observing the slow but steady change in the orbit of the planet as it passes in front of its host star.

Finding it surprisingly bright compared to other exoplanets, they had long assumed that it particularly reflected starlight. But they now believe Kepler is hotter than expected due to the star’s gravitational pull.


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