Exoplanets that orbit so close to their parent stars are not uncommon and are commonly referred to as “hot Jupiters.” 
Joana Campos Meteorized Portugal 03/09/2023 05:00 6 mins
A recent study published in the journal Monthly Notices of the Royal Astronomical Society states: A team of international researchers studied the exoplanet TOI-4860 b, located about 261 light-years from Earth and whose orbital period is about 1.52 days. Low mass star, i.e. a star that is smaller than our Sun.
TOI-4860 b is unique due to its size relative to its parent star and its surface temperatures lower than that of “hot Jupiters” and the fact that it contains large amounts of heavy elements.
These properties explain why researchers classify TOI-4680 b as a “hot Jupiter.” and could challenge traditional models of the formation of planetary systems while offering new perspectives on these processes. “According to the canonical model of planet formation, the lower the mass of a star, the lower the mass of the disk of material around that star,” said Dr. George Dransfield from the University of Birmingham and co-author of the study.
“According to the canonical model of planet formation, the lower the mass of a star, the lower the mass of the disk of material around that star,” said Dr. George Dransfield from the University of Birmingham and co-author of the study.
“Because planets form from this disk, it was expected that high-mass planets like Jupiter would not form. However, we were curious and wanted to check out the candidate planets to see if this was possible. TOI-4860 is our first confirmation and is the lowest mass star that could host such a massive planet.”
What dimensions does the TOI-4860b have?
For the study, the researchers used almost 10,000 observatories and instrumentsincluding TRAPPIST-South/North, SPECULOOS South Observatory and MuSCAT3, to collect photometric and spectroscopic data on various transits of TOI-4860 b as it passed in front of its host star.
At the end of the day, The researchers concluded that TOI-4860 b measures about 0.76 times the radius of Jupiter, while its parent star measures about 0.34 times the radius of our Sun. For comparison, Jupiter’s radius is about 70,000 km, while the Sun’s radius is about 0.34 km. about 700,000 km, which means Jupiter’s radius is about 10% of our Sun’s radius.
With these numbers, TOI-4860 b’s radius is about 53,000 km, with the radius of its parent star being 238,000 km The radius of TOI-4860 b is about 22% of the radius of its parent star.
How did such a large exoplanet form around such a small star?
“One clue to what might have happened lies in the properties of the planets, which appear to be particularly rich in heavy elements,” said Dr. Amaury Triaud, professor of exoplanetology at the University of Birmingham and lead author of the study.
“We also discovered something similar in the host star. It is therefore likely that an abundance of heavy elements catalyzed the planet formation process.” Researchers found that TOI-4860 b contains heavy elements based on its density, which is 1.55 times higher than that of Jupiter, which is mostly made up of lighter elements such as hydrogen and helium.
The researchers found that TOI-4860 b contains heavy elements due to its density, which is 1.55 times that of Jupiter.
Based on these findings, particularly given TOI-4860 b’s large radius relative to its parent star, researchers have since referred to TOI-4860 b as a “hot Jupiter.” Its surface temperature is about 350 °C, much lower than that of the “hot Jupiters”, some of which can reach 2750 °C on the sunny side.R.
Previous studies have found that hot Jupiters have orbital periods of more than 10 days and that their systems also host other planets. So, TOI-4860 offers astronomers a unique opportunity to study these unique exoplanets and gain insight into their formation and evolution.
In 2019, astronomers confirmed the existence of TOI-677 b, a Jupiter-sized exoplanet located about 463 light-years from Earth with an approximate surface temperature of 979 °C.
For the next steps, the researchers plan to use the Very Large Telescope in Chile in the hope of identifying additional hot Jupiters or even exoplanets with similar properties.