A massive, Jupiter-sized exoplanet has been discovered orbiting a small, low-mass star and this discovery is challenging theories on how planets form around their stars. The planet, called TOI-4860 b, is about the same size as Jupiter and orbits its star once every 1.5 Earth days, classifying it as a warm Jupiter. This is unusual because planets this large are not supposed to form around low-mass stars.
The exoplanet orbits the red dwarf star TOI-4860. Located in the constellation of Corvus the crow some 261 light years away, TOI-4860 has a mass equivalent to just around a third of our Sun.
To get this large, the team that discovered TOI-4860 b believes that the planet may have formed from a disk of material that was enriched in heavy elements. This enrichment could have helped the planet to grow to its current size.
The discovery of TOI-4860 b challenges our understanding of how planets form. The traditional model of planet formation says that planets form from disks of gas and dust that surround young stars. The amount of material in these disks is thought to be related to the mass of the star. So, a low-mass star would have a less massive disk, and therefore would not be able to form a planet as large as TOI-4860 b.
However, astronomers believe that there may be another way for planets to form around low-mass stars. These planets may have formed from the merger of smaller planets. This would require a very specific set of circumstances, but it is possible.
TOI-4860 b was first spotted by NASA’s Transiting Exoplanet Survey Satellite (TESS), which hunts planets outside the solar system by looking for tiny drops in the brightness of light emitted by stars. Those dimmings are caused as an orbiting planet crosses between the host star and our telesocpes.
The discovery of TOI-4860 b is a reminder that we still have a lot to learn about how planets form. This discovery is just one more piece of the puzzle, and it will be exciting to see what else we learn in the future.
Finding planets in locations we don’t expect and in regions that defy our current understanding is an important reason why astronomers scan the heavens in search of other worlds. The universe is a vast and mysterious place and we have only just begun the quest for life in the universe and it all starts with these observations, performed by vigilant ground and space-based telescopes.