An international team of scientists announced the discovery of an exoplanet that has the shape of an American football or rugby ball. It is the first time in history that a exoplanet with this kind of shape; Until now, astronomers had only theorized.
The results of this work, in which researchers from the Center for Astrobiology (CAB) have participated, are published in the journal Astronomy & Astrophysics.
Powerful tidal forces
The data, provided by the CHEOPS mission of the European Space Agency (ESA), reveal that the exoplanet WASP-b was deformed by strong tidal forces between the planet and its host star, WASP-103, hotter and larger than our Sun.
“This exoplanet takes less than a day to go around its star and its shape is more similar to that of a rugby ball than to that of a sphere”, says Jorge Lillo- Box, a researcher at the Center for Astrobiology and co-author of the study.
The phenomenon it is not weird. On Earth, for example, the tides of the oceans are produced, the result of the influence of the Moon that ‘pulls’ our planet slightly while it orbits us.
The Sun also has a small but significant effect on the tides, but it is too far from Earth to cause large deformations.
In this case, the star around which it revolves the exoplanet, called WASP103, in the constellation of Hercules, has a similar temperature and is about 1.7 times larger than our Sun.
The exoplanet, WASP-103b, is a gas giant planet almost twice the size of Jupiter and 1.5 times its mass and its extreme proximity to its host star could cause gigantic tides, something that until now had not been confirmed.
Data from ESA’s Cheops space telescope , Hubble and Spitzer
Using new data from the Cheops Space Telescope of l a ESA, combined with data obtained by the NASA/ESA Hubble Space Telescope and the NASA Spitzer Space Telescope, the astronomical community detected an oval shape.
These data have been supplemented with high spatial resolution images from the AstraLux instrument, at the Calar Alto Observatory (Almería), thanks to which the origin of the signal was confirmed.
Cheops measures the transits of exoplanets, that is, the changes in light that occur when a planet passes in front of its star, but this time, its high precision has allowed to detect the tiny signal that indicates that WASP-103b is undergoing a deformation caused by tidal forces.
Love number
The Cheops data allowed us to derive a parameter called the Love number, which measures how mass is distributed within a planet, which can give information about its internal structure and the materials and determine in what proportion it can be rocky, gaseous or liquid.
“Understanding this internal structure is essential to understand the processes of formation and evolution of planetary systems”, points out Jorge Lillo-Box .
The Love number of the exoplanet WASP- b is similar to that of Jupiter, suggesting that the internal structure could be similar, even though WASP-103b has double the radius.
This is because it is ‘inflated’, probably due to the heat emanating from its star host and by other mechanisms that in the future will be able to be studied with the James Webb Telescope, the largest space observatory in history that will help to find out much more about the internal structure and nucleus of exoplanets and, therefore, about their formation .
The study also indicates that the orbital period of WASP-103b could be increasing and that the planet s e is slowly moving away from the star, which would indicate that there is another factor influencing the planet alongside tidal forces, but more observations will be needed to find out why this is happening.
(With information from DW)
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