Space: a planet shaped like a rugby ball discovered by the Cheops satellite

WASP-103b is not an exoplanet like any other. Discovered by the Cheops observation satellite, it has a unique shape, not unlike that of a rugby ball. Spotted 1,800 light years from the solar system, WASP-103b is located in the constellation of Hercules.

The deformation of this exoplanet is due to the effect of attraction caused by the proximity to its star.

However, the team of astronomers from the University of Porto, led by Susana Barros, a Portuguese astrophysicist, was looking to study this phenomenon.

Their observations gave rise to a study, published Tuesday, January 11 in the journal Astronomy & Astrophysics.

Jacques Laskar, co-signer and astrophysicist at the Paris-PSL Observatory, explains that the group of scientists wanted to “know if we could detect the shape of a planet by observing its transit curve”.

The latter refers to the variations in the luminosity of a star when a planet passes in front of it. The idea was that if we have a planet like “a rugby ball or a soccer ball passing in front of the star, we don’t have the same transit curve”, he explains.

The deformation was also to inform researchers about the internal structure of the exoplanet, rocky or gaseous. Indeed, in a press release from the European Space Agency (ESA), Susanna Barros underlines that “the resistance of a material to deformation depends on its composition”.

Similarities with Jupiter

WASP-103b is remarkably close to its star, WASP-103. About 50 times closer to its sun than the Earth is to hers, to the point of circling it in just twenty-two hours, compared to 365 days for our blue planet.

This is also why WASP-103b is so distorted: the closer a planet is to its star, the more it undergoes its effect of attraction, called tidal force. Earth is also subject to it, but to a lesser extent. The Moon and the Sun periodically deform it by a few tens of centimeters. Nothing compares to the colossal force exerted on WASP-103b.

Intrigued by this unusually shaped celestial body, astronomers plan to obtain observation time with the James-Webb Space Telescope. They have already determined that WASP-103b has one and a half times the mass of Jupiter, with a radius twice as large.

The team also assumes that, like Jupiter, this exoplanet has a solid core, enveloped in a liquid layer, itself surrounded by a gaseous atmosphere. The planet in the shape of a rugby ball has not yet revealed all its mysteries, Jacques Laskar is particularly convinced “that it could not have been born in this place”.

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