TESS discovered a large planet near a small star

Using data collected by the TESS Space Telescope, a team of researchers from the Carnegie Institution discovered a previously unknown exoplanet. It orbits the star TOI-5205, located 280 light-years from Earth.

The exoplanet of the red dwarf in the artist’s image. Source: ESO/L. Calçada

TOI-5205 is a red dwarf. Its mass and radius are 0.39 solar, while the luminosity is 50 times less than that of our star.

As for the newly discovered exoplanet, designated TOI-5205b, it is a gas giant. Its mass exceeds the mass of Jupiter by 1.08 times, its radius by 1.03 times. TOI-5205b makes one revolution around its parent star in 1.63 days, its equilibrium temperature is estimated at 460 ℃. 

The find is interesting by the mass ratio between an exoplanet and a star. It is 0.3%, which is one of the highest known indicators. Another interesting detail is that due to the size ratio, the depth of TOI-5205b transits is 7%. This means that during the passage of an exoplanet against the background of a star, the brightness of the last decreases by 7%, which is also one of the largest known indicators.

Bodies like TOI-5205b do not fit well into modern theories of planet formation, suggesting that massive gas giants should not form around low-mass red dwarfs. Therefore, it will almost certainly become a target for new observations, including using the James Webb Telescope.

Earlier we talked about how TESS discovered two super-Mercuries.

According to https://arxiv.org

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