Astronomers are baffled by the peculiar characteristics of a recently discovered planet and are unsure of how it came to be this way.
It is a gas giant called TOI-4860b that is around 260 light-years away and about the size of Saturn. All is well thus far.
However, TOI-4860b orbits a tiny, old star that is only a third as massive as the Sun, completing each brisk circle in just 1.52 days. It joins a small but expanding group of odd worlds that present an intriguing riddle. Currently, no known formation processes for such chonky planets surrounding such dwarf stars are known.
Two distinct publications describing the exoplanet have been posted on the preprint service arXiv, one of which was submitted to Astronomy & Astrophysics and the other of which was printed in the Monthly Notices of the Royal Astronomical Society.
Astonishing gaps are forming in the kinds of worlds that exist in the universe as astronomers discover and confirm an increasing number of exoplanets — about 5,500 as of this writing.
On the other hand, new worlds are also appearing in unexpected locations. like enormous planets orbiting little stars.
Dense clusters in dust and gas clouds produce a disk that feeds into the developing star like water down a drain when stars form. Whatever is remains of the disk transforms into planets when the star has finished developing. According to several models, the mass of the star determines how much material is in the disk; larger stars have more material, while tiny stars have much less.
It is obvious where this is going. Our calculations predict that red dwarf stars with masses and radii less than roughly 40% of the Sun’s shouldn’t have enough material to support exoplanets over a specific size. But we keep coming across them. A dozen or so of them have been found orbiting really small stars.
Given that TOI-4860b was identified and examined by two distinct teams utilizing two different sets of tools and yielded almost comparable results, it represents a promising candidate for further research.
The exoplanet has 76.6 percent the radius and 27.3 percent the mass of Jupiter, according to a team led by astronomer José Manuel Almenara of the French National Center for Scientific Research, and it orbits a star that is 34 percent the mass and radius of the Sun.
The University of Birmingham in the UK, under the direction of astronomer Amaury Triaud, discovered TOI-4860b to have a radius that is 76 percent that of Jupiter but a mass that is 67 percent that of Jupiter.
It will undoubtedly take some additional effort someplace to determine the planet’s precise mass. However, the radius is practically identical, indicating that the exoplanet is a stunning 22 percent of its star’s radius.
What then should we do with this knowledge?
Each team, though, contributed something unique. It has been hypothesized that gravitational interactions between exoplanets may have pushed TOI-4860b in towards its present close orbit because Almenara and his colleagues discovered evidence of a second, undiscovered exoplanet with an orbital period of 426.9 days and a mass at least 1.66 times that of Jupiter.
Triaud and his team discovered that the ratio of heavy elements on both the star and the exoplanet is identical, which may hold information about how they formed. However, the researchers warn that this interpretation may be flawed because it is based on mass measurements of the exoplanet that were obtained under unfavorable circumstances.
However, both teams assert that additional research is necessary before we can fully understand the composition of TOI-4860b’s atmosphere. This might contribute to unraveling the riddle surrounding these oddly heavyweight realms.
The two papers are available on arXiv. They can be found here and here.
