The Khufu Exoplanet Monitoring Satellite has made it possible for the first time to detect the deformation of a planet – close to a rugby ball – through the gravitational effect of its star.
The rare bird, called WASP-103b, is located in the constellation Hercules, at a very modest distance of about 1,800 light-years from the solar system.
The team of astronomers, led by Portuguese astrophysicist Susana Barros at the University of Porto, was looking for a sample highly distorted due to its proximity to its star, said Jacques Lascar, co-signer of the study published Tuesday in the Journal of Astronomy and Astrophysics.
“We wanted to see if we could detect a planet’s shape by observing its transit curve,” meaning the contrast in the light a star produces when passing in front of it. As an astrophysicist in Paris -PSL observatory explains. The idea is that if we had a planet like “a rugby ball or soccer ball passing in front of the star, we wouldn’t have the same transit curve”.
The deformation of the planet, for its part, should provide information about its internal structure, rocky or gaseous. Susanna Barros noted in a press release from the European Space Agency (ESA) that “the resistance of a material to deformation depends on its composition.”
For a planet to be so distorted, it must be very close to its star, to better undergo the effect of attraction, called tidal force. It is the same force that the Moon, and to a lesser extent the Sun, exerts on our Earth, by distorting it periodically by a few tens of centimeters. Hence its famous “potato” form.
WASP-103b is remarkably close to its star, WASP-103. About 50 times closer to its sun than its Earth. To the point of doing the tour in just 22 hours, versus 365 days for our blue planet.
Thus WASP-103b is subject to tremendous tidal force, which, if it fails to tear it apart, gives it its particularly rare, off-the-ball shape.
The team led by Susanna Barros was able to determine that if WASP-130b was one and a half times the mass of Jupiter, the gas giant in our solar system, then its radius was twice as large. “So it must have been very swollen from the hotness of its star and possibly other mechanisms,” said Susanna Barros.
Scientists assume that, like Jupiter, it has a solid core, surrounded by a liquid layer, surrounded by a gaseous atmosphere. But to be clear, they plan to have time to observe with the James Webb Space Telescope.
Thus, “to better understand also how she managed to get there,” adds Jacques Lascar, convinced “she was not born in this place.”
