Scientists have discovered a giant, gas planet that revolves around a small red dwarf, a rare combination that astrophysics find it difficult to explain.

The star-6894 star looks very much like others in our galaxy. It is a red dwarf, a very small star, brightness and mass star, reaching only 20% of our sun. Planetologists have long been assumed that such stars do not provide the conditions necessary for the formation and “hosting” of giant planets.

But an international group of astronomers identified the undisputed signature of a gas planet that revolves around the tiny Ti-6894, according to a study published today in the Nature Astronomy scientific journal.

Ti-6894 is the smallest star that scientists know that has such a colossus in orbit around it. The giant planet, baptized on this-6894b, has a radius slightly larger than Saturn but only half of its mass. Makes a complete rotation around the star of every 3.36 days.

To discover him, scientists made observations with the help of photometric data from the TESS satellite (Transiting Exoplanet Satellite) as part of the search for giant exoplanets that revolve around stars. The existence of the TOI-6894B was then confirmed by soil telescopes, especially by the very large telescope (VLT) of Chile.

“Most of our stars in our galaxy are small like this, with a small mass and we have not believed so far that they could be accompanied by giant gaseous planets,” said one of the authors of the study, Professor of the University of Warwick Daniel Bayilis,

“It is a discovery that is of interest. We don’t really understand how a star with such a low mass can form such a huge planet! This is one of the goals of our research on the exoplanets: Finding planetary systems different from ours, we can simulate simulations and better understand the formation of our own, “said Vincent Van Eilen, a researcher at the Malard Space Lab.

The dominant theory for the creation of planets is that of accumulation. The process begins on the protagonist disc, a concentration of gases and dust rotating around a newborn star. The new planet is formed by the gradual accumulation of matter. As it grows, it attracts gases that form a dense atmosphere and turns into a gas planet.

According to this theory, however, the formation of giant planets is more difficult around stars with a small mass, because the amount of gases and dust on the primary disc is too limited to start this process.

An alternative theory explains the formation of these planets, citing gravitational instability. The primary disc can be made unstable because of its itself gravity and fragment, with gases and dust then forming a planet.

The data available, however, do not allow the formation of the Toi-6894B to be explained based on this theory. At the origin of the planet, the detailed study of its atmosphere may be light on the origin of the planet, which could give valuable indications of the size and structure of its core.

This atmosphere is interested in astronomers for other reasons: Although most giants, gaseous exoplanets that have been found to date are “hot” like Jupiter, with temperatures ranging between 1000-2000 Kelvin (726-1726 degrees Celsius), the TOI-689 Kelvin (146.85 ° C). Scientists also believe that methane dominates in its atmosphere.

The atmosphere of the planet will be studied with the James Webb Space Telescope of the next 12 months.