A team of astronomers has discovered a strange star system in which an “impossible” gas planet orbits a red dwarf star called TOI-5205. The new discovery challenges our understanding of how planets form and could help astronomy redefine many old concepts.
Red dwarfs are smaller in size and surface temperature than our Sun, and are the type of stars commonly found in the Milky Way. Because of their small size, these stars are usually only half as hot as the Sun and emit more red light. Red dwarfs are long-lived and not very bright.
When compared to a large star system, a system with a red dwarf in the middle will contain more planets. However, the history of these star systems does not allow a gas giant to form. That notion soon ceased to be accurate.
An illustration of a gas planet orbiting the star TOI-5202 – Photo: Carnegie Institute of Science.
The team of scientists named the strange exoplanet (extrasolar planet) TOI-5205b. Experts from the Carnegie Institution for Science have published a new report in The Astronomical Journal, and determined that the newly discovered planet may become a research target for the Transiting Exoplanet Survey Satellite. planet (TESS) by NASA.
“The interstellar star, TOI-5202, is about four times the size of Jupiter, yet it can contain a planet about the size of Jupiter, which is really surprising!”, the researcher said. rescue Shubham Kanodia said.
In previous studies, astronomers discovered a handful of gaseous planets orbiting ancient red dwarf stars. But so far, no gas planet has existed in a star system as “lightweight” as TOI-5205.
For ease of visualization, Jupiter’s orbit around the Sun can be compared to a pea moving around a grapefruit; and in the case of planet TOI-5205b, we have to take a pea and a lemon for comparison.
In fact, when TOI-5205b passed by the mid-stellar star, it blocked 70% of the light emitted by TOI-5205. This rare case is one of the largest “blinds” in the history of astronomy.
On the left is the pair of objects TOI-5205 and TOI-5205b, on the right is the Sun compared to Jupiter – Photo: Carnegie Institute of Science.
Normally, planets form in accretion disks of gas and dust that orbit a young star. According to the current hypothesis, the formation of gas planets would require 10 Earth-equivalent masses of matter to form the planet’s solid core, after which gravity from the core would attract gas from the vicinity. to form a gas giant.
“The existence of TOI-5205b expands our understanding of the accretion disks at which planets form,” explains researcher Kanodia.
“Initially, without enough solid matter to form the core, a gaseous planet would not have been able to form. And finally, if the accretion disk evaporated before the core appeared, the gas planet could not exist either. However, TOI-5205b overcome these barriers and was born”.
He concludes: “Based on what we understand about planetary birth, TOI-5205b should not have existed; it’s a ‘forbidden’ planet.
According to the data collected by the scientists, the light emitted by TOI-5205b is very consistent with the instruments available on the James Webb Space Telescope. With modern equipment that can be considered a marvel of engineering, we will clearly know the process of mysterious planet formation.