DIn the universe, the attraction that one body exerts on another is at the origin of what is called a tidal effect. Exactly as the Moon orchestrates the high and low tides of the terrestrial oceans and deforms the crust of our beautiful planet, dressing it with a bead of almost thirty centimeters. Thanks to the new possibilities offered by the Cheops satellite, launched by ESA in December 2019 with the aim of measuring and characterizing exoplanets, a European team of astronomers – including French people – has managed to observe a deformed extrasolar world at the extreme, not by its natural satellite, but by the proximity of its host star. A first which is the subject of a publication in the scientific journal Astronomy & Astrophysics.
READ ALSOCheops: a mission to shed light on exoplanets
Hot jupiter
This exoplanet is also what we call a hot Jupiter, since it has a mass close to that of the giant planet of the solar system while being subjected to a high temperature because it is much closer to its star. Indeed, WASP-103b revolves around its parent body in just 22 hours compared to 12 years for Jupiter and 365 days for Earth. A proximity which, in addition to extreme temperatures, exposes it to a very strong effect of tides likely to deform it significantly. A deformation that scientists were able to measure, for the first time, by combining new data from Cheops with those already obtained by Hubble and by NASA’s Spitzer space telescope.
Thanks to the high precision, but also to the ease of pointing of Cheops which allowed them to observe no less than twelve transits of WASP-103b in front of its star, each time measuring the decrease in luminosity caused by its passage, the The team was able to detect the tiny signal of the tidal deformation of WASP-103b. Which does not have much of a sphere and looks more like a rugby ball. Indeed, while the radius of this planet is about 140,000 kilometers, it has an enormous bead of nearly 10,000 kilometers in the direction of its star, to which it always presents the same face. Beyond the very exotic aspect of this planet, having been able to measure this deformation opens up new horizons. This could help determine the internal structure of this hot Jupiter-like exoplanet. Indeed, the way a material deforms is intrinsically linked to its composition …