The European Space Agency’s (ESA) Cheops mission has detected an unusually deformed exoplanet that is in the shape of a rugby ball. This is a very important discovery as it is the first time ever that a deformed planet has been observed.
Known as WASP-103b, this planet is situated in the constellation of Hercules. Its deformed shape is based on the powerful tidal forces between the planet and the host star, as well as how close they are located to each other. The star WASP-103 is approximately 1.7 times bigger and 200 degrees hotter than our sun.
The fact that WASP-103b is nearly twice the size of Jupiter and 1.5 times its mass, in addition to it taking less than a day to orbit its star, the planet is getting tugged at and experiencing huge tides. Astronomers have figured out how the tidal forces are affecting the planet’s shape, thanks to data from the ESA’s Cheops space telescope, NASA/ESA Hubble Space Telescope, and NASA’s Spitzer Space Telescope.
The parameter (also called a Love number) that reveals how the mass is spread throughout the planet was calculated by measuring WASP-103b’s transit light curve. Susana Barros from the Instituto de Astrofísica e Ciências do Espaço and University of Porto, Portugal, explained this in further detail, “The resistance of a material to being deformed depends on its composition.” “For example, here on Earth we have tides due to the Moon and the Sun but we can only see tides in the oceans. The rocky part doesn’t move that much. By measuring how much the planet is deformed we can tell how much of it is rocky, gaseous or water.”
WASP-103b’s Love number is close to that of Jupiter’s which indicates that the internal compositions of both planets may be similar. “In principle we would expect a planet with 1.5 times the mass of the Jupiter to be roughly the same size, so WASP-103b must be very inflated due to heating from its star and maybe other mechanisms,” Barros stated, adding, “If we can confirm the details of its internal structure with future observations maybe we could better understand what makes it so inflated. Knowing the size of the core of this exoplanet will also be important to better understand how it formed.”
The experts noticed another odd feature about the planet as it seems to be moving away from the star and its orbital period may be getting longer. This suggests that something other than the host star may be affecting the planet, like a companion star or an elliptical orbit, but the mystery remains unsolved at this time. On the other hand, the orbital period may actually be getting shorter, but more observations need to be conducted in order to know exactly what is going on with this very strange planet. (An artist’s impression of WASP-103b near its host star can be seen here.)
The study was published in Astronomy & Astrophysics.