Massive 'forbidden planet' orbits a strangely tiny star only 4 times its size

The finding might cast doubt on our understanding of the formation of gas giants like Jupiter.

An unique planetary system with a Jupiter-sized planet circling a tiny star that is only four times the size of the gas giant in our solar system has been found by astronomers. This "forbidden" arrangement of a large planet circling a small star may cast doubt on ideas regarding the formation of gas giant planets.

The "exoplanet," also known as an extrasolar planet, revolves around the red dwarf star TOI 5205, which is much colder and smaller than the sun. These M-dwarf stars, the most prevalent form of stellar entity in the Milky Way, are smaller than the sun and have temps that are comparatively cool.

Although this class of stars typically holds more planets than other star types, it was originally thought that their formation makes it improbable that gas giants will circle them. This exoplanet, TOI 5205b, was found by scientists using NASA's Transiting Exoplanet Survey Satellite (TESS) observatory, which casts doubt on that idea. With the aid of different ground-based telescopes and instruments, the crew was able to corroborate and describe the planet.

Team head and Carnegie Science astronomer Shubham Kanodia said, "The host star, TOI-5205, is just about four times the size of Jupiter, yet it has managed to create a Jupiter-sized planet, which is quite amazing!"

Although gas giants have been found circling M dwarf stars in the past, none of them have been found orbiting a TOI-5205 that is so low mass.

Protoplanetary discs, rotating spheres of gas and material that encircle young stars, are where planets are born. Its center star was created when the same material imploded, leaving behind this material. Planet centers are created when dense regions fall due to their own gravity, at which point they begin to gather more material.

According to current planet formation theories, it would require material 10 times the mass of Earth to give rise to a gas giant. This first creates a rocky center, and from this core, a huge planet eventually develops by accumulating gas. But this procedure must move swiftly.

"A gas giant planet cannot initially develop if there is not sufficient rocky material in the disk to create the original nucleus. Finally, it is impossible to create a gas giant planet if the disk evaporates away before the huge center is created. Nevertheless, TOI-5205b developed despite these barriers "Kanodia provided a statement explanation. "TOI-5205b should not exist; it is a 'forbidden' planet," says the statement, "based on our nominal present knowledge of planet creation."

Imagine our star, the sun, shrunk to the size of a grapefruit to get an idea of how unbalanced this system is compared to the celestial systems that scientists anticipate. Jupiter, the biggest gas giant in our solar system, would be about the size of a garden pea after that size decrease.

A bean circling a lemon is more like the TOI-5205 system.

The size difference is so large that when TESS used the transit technique, which measures the light loss brought on by planets passing in front of their stars, the light loss was 7% of the star's overall light output.

The biggest known reduction in light produced by an extraterrestrial transit, TOI-5205's dimming by this Jupiter-sized exoplanet.

Because of this sharp decrease in light, or formally, "large passage depth," the system might be perfect for further research using the James Webb Space Telescope (JWST).

The atmosphere of TOI-5205 b could be better understood and the processes that gave rise to this "forbidden" planet's formation could be clarified through observations made with the JWST.

The team's research is published in The Astronomical Journal