Exoplanet TOI-4860 b, which orbits a low-mass star, or a star smaller than our Sun, and is located about 80 parsecs (261 light-years) from Earth, was the subject of a recent study by a group of international researchers that was published in the Monthly Notices of the Royal Astronomical Society. Exoplanets that orbit their parent stars so closely are referred to as “hot Jupiters” and are not rare.
Toi-4860 b, however, is distinct due to its relative size in relation to its parent star, as well as its lower surface temperatures in comparison to “hot Jupiters” and the presence of significant amounts of heavy elements. These characteristics have led scientists to categorize TOI-4680 b as a “warm Jupiter”; they may also challenge current theories about how planetary systems develop while revealing fresh information about these procedures.
“Under the canonical planet formation model, the less mass a star has, the less massive the disc of material is around that star,” said Dr. George Dransfield, a co-author on the paper and a recent graduate of the University of Birmingham. “High-mass planets like Jupiter were largely anticipated not to exist since planets are formed from that disc. However, we were interested in this and sought to investigate planetary prospects to determine whether it was feasible. Our first confirmation comes from TOI-4860, the lowest mass star to support a planet with such a high mass.
For the study, photometric and spectroscopic data on numerous transits of TOI-4860 b passing in front of its parent star were gathered using a variety of observatories and equipment, including TRAPPIST-South/North, the SPECULOOS South Observatory, and MuSCAT3.
The researchers determined that TOI-4860 b is roughly 0.76 Jupiter’s radius and that of its parent star is roughly 0.34 our Sun’s radius. The Sun’s radius is roughly 700,000 kilometers (435,00 miles), while Jupiter’s radius is roughly 70,000 kilometers (43,500 miles). Jupiter’s radius is therefore roughly 10% that of our Sun. With these figures, TOI-4860 b’s radius is estimated to be 53,200 kilometers (33050 miles) and that of its parent star to be 238,000 kilometers (147,886 miles), or about 22 percent and more than double the distance between Jupiter and our Sun, respectively. However, how could such a sizable exoplanet develop around such a dim star?
“A hint of what might have happened is hidden in the planetary properties, which appear particularly enriched in heavy elements,” claimed Dr. Amaury Triaud, lead author of the study and professor of exoplanetology at the University of Birmingham. Since we found a comparable phenomenon in the host star as well, it is most likely that an abundance of heavy elements accelerated the process of planet formation.
Given that TOI-4860 b has a density that is 1.55 times greater than that of Jupiter, which is mostly made up of lighter components like hydrogen and helium, the researchers inferred that TOI-4860 b contains heavy elements.
The researchers characterize TOI-4860 b as a “warm Jupiter” in light of these findings, particularly those pertaining to the large radius of TOI-4860 b in comparison to its parent star. This is because TOI-4860 b’s surface temperature is much lower than that of “hot Jupiters,” some of which have dayside temperatures as high as 2750 degrees Celsius (4900 degrees Fahrenheit), and is much lower than the temperature of “hot Jupiters” generally. According to earlier research, heated Jupiters have orbits that are longer than 10 days and have many planets in their systems. Astronomers now have a rare chance to study these distinctive exoplanets and learn more about how they formed and evolved thanks to TOI-4860.
The researchers have been given access to the Very Large Telescope in Chile for their upcoming work, and they intend to utilize it to look for additional warm Jupiters or possibly exoplanets with comparable properties.
Other warm Jupiters that have been confirmed include EPIC 211418729 b and EPIC 211442297 b. Both are believed to have surface temperatures of 445.85 degrees Celsius (834.5 degrees Fahrenheit) and 408.85 degrees Celsius (768 degrees Fahrenheit), respectively. They were both identified in 2017 and are situated at 1,569 and 1,360 light-years from Earth. The existence of TOI-677 b, an exoplanet the size of Jupiter that is 463 light-years from Earth and has a surface temperature of about 979 degrees Celsius (1,794 degrees Fahrenheit), was confirmed by scientists in 2019.
