An impossible exoplanet has been discovered

 A team of astronomers led by Shubham Kanodia of Carnegie has discovered an unusual planetary system in which a large gas giant exoplanet revolves around a little red dwarf star called TOI-5205. Red dwarfs are the most common stars in the Milky Way (they are smaller and 'cold' than the Sun). They have very low brightness, but extremely long life. Although red dwarfs host more planets on average than other more massive stars, they make them unlikely candidates for giant planets. In this  image we can see an artistic representation of a gas giant orbiting a small red dwarf star called TOI-5205.

Credit: Katherine Cain, courtesy of the Carnegie Institution for Science

The new planet, TOI 5205b, was first identified as a possible candidate by NASA's Transiting Exoplanet Satellite Survey (TESS). The Kanodia team then confirmed its planetary nature and characterized it. A small number of gaseous giants were discovered in orbit around dwarf stars M (red dwarfs). But until now no gas giant (only 4 times smaller than the parent star) has been found in a planetary system around a small-mass star like TOI-5205. When TOI 5205b passes in front of its star, it blocks about 7% of its light, one of the largest transits of any known exoplanet.  

Planets are born into the spinning disk of gas and dust surrounding the young stars. The most commonly used theory of the formation of gaseous planets requires that about 10 Earth masses of this rock material accumulate and form a massive rocky nucleus, After that, large quantities of gas are quickly swept away from the nearby regions of the disk to form the giant planet that we see today. The time frame for this is crucial. The James Webb Space Telescope could shed light on its atmosphere and offer some additional clues to the mystery of its formation.

Source: Carnegie Science, The Astronomical Journal