An international team of scientists has discovered a Jupiter-sized exoplanet orbiting a low-mass star called TOI-4860, located in the constellation Corvus, a finding that serves to deepen our understanding of planetary formation.
The newly identified gas giant, named TOI-4860 b, is an unusual planet for two reasons: stars of such low mass are not expected to host Jupiter-like planets, and the exoplanet appears to be particularly enriched in heavy elements.
The study, led by astronomers at the University of Birmingham, is published in the Monthly Notices of the Royal Astronomical Society.. In confirming the planet, which was initially identified by NASA's Transiting Exoplanet Survey Satellite (TESS), several observatories were involved: the SPECULOOS Southern Observatory, located in the Atacama desert (Chile), and the Subaru telescope in Hawaii .
The monitoring of this star and the confirmation of its planet was the initiative of a group of PhD students from the SPECULOOS project.. George Dransfield, one of those PhD students, who has just presented his thesis in Birmingham, explains that according to the canonical model of planet formation, the less mass a star has, the less massive is the disk of material that surrounds it.
“Since planets form from that disk, it was expected that high-mass planets, such as Jupiter, would not form. However, we were curious about it and wanted to check the planet candidates to see if it was possible,” he says.
According to the researcher, “TOI-4860 is our first confirmation and also the lowest-mass star that hosts such a high-mass planet.”
Amaury Triaud, Professor of Exoplanetology at the University of Birmingham, who led the study, notes that planets like TOI-4860 b are vital to further understanding of planetary formation.
A clue, he explains, to what might have happened lies in the planetary properties, which seem particularly enriched in heavy elements.
“We have also detected something similar in the host star, so it is likely that an abundance of heavy elements catalyzed the planet formation process,” he adds.
It takes about 1.52 days for the new gas giant to complete a full orbit around its host star, and since its host is a cool, low-mass star, the planet itself can be called a “hot Jupiter.”