A team of astronomers has discovered an unusual planetary system in which a large gas giant planet orbits a small red dwarf star called TOI-5205. Their discoveries challenge old ideas about the formation of planets. Researchers led by Shubam Kanodia of the Carnegie Institute for Science have published their findings. Astronomy Journal.

Smaller and cooler than our sun, M dwarfs are the most common stars in our Milky Way galaxy. Because of their small size, these stars are typically about twice as hot as the Sun and much redder. They are very low in brightness but extremely long-lasting. Although red dwarfs contain, on average, more planets than other more massive star types, their formation histories do not make them possible candidates for hosting gas giants.

Artist’s concept of a large gas giant planet orbiting a small red dwarf star named TOI-5205. So far, no gas giants have been found in the planetary system around a low-mass M-dwarf like TOI-5205. Credit: Image by Catherine Kane, courtesy of the Carnegie Institute for Science

The newly discovered planet TOI 5205b was first identified as a potential candidate by NASA’s TESS (Tess) satellite. Kanodia’s team, which included Anjali Piette, Alan Boss, Johanna Teske, and Carnegie’s John Chambers, later confirmed its planetary nature and characterized it using a variety of ground-based instruments and instruments.

“The host star TOI-5205 is about four times the size of Jupiter, but somehow managed to form a Jupiter-sized planet, which is pretty amazing!” cried Kanodia, an expert in studying these stars that make up nearly three-quarters of our galaxy but are invisible to the naked eye. He also wrote a blog post about the discovery.

Few gas giants have been found orbiting ancient M dwarf stars, but so far no gas giants have been found in the planetary system around a low-mass M dwarf such as TOI-5205. To understand the size comparison, a Jupiter-like planet orbiting a Sun-like star can be compared to a pea orbiting a grapefruit; For TOI-5205b, it looks more like a pea swirling around a lemon, as the main star is much smaller. In fact, when Jupiter-mass TOI 5205b passes in front of the carrier, it blocks about seven percent of its light; it is one of the largest known transiting exoplanets.