An international team of scientists has discovered an unusual new exoplanet that could shed light on planet formation.
The scientists found the unusual new exoplanet orbiting a low-mass star called TOI-4860, in the Corvus constellation.
The Jupiter-sized planet, named TOI-4860 b is unusual for two reasons. First, stars of such low mass are not expected to host planets like Jupiter, and second, the planet appears to be particularly enriched by heavy elements.
The study, ‘An M-dwarf accompanied by a close-in giant orbiter,’ is published in a letter within the Monthly Notices of the Royal Astronomical Society, and is set to deepen scientist’s understanding of planet formation.
How was the exoplanet discovered?
Initially, the exoplanet discovery was made using NASA’s Transiting Exoplanet Survey Satellite as a drop of brightness while transiting in front of its host star. However, this data alone has not sufficient to confirm it was a planet.
To validate the planetary data, the team used the SPECULOOS South Observatory, located in the Atacama Desert in Chile, to measure the planetary signal in several wavelengths.
The team also observed the planet just before and after it disappeared behind its host star. During their observation, they found that there was no change in light, meaning that the planet was not emitting any.
Finally, the team collaborated with a Japanese group using the Subaru Telescope in Hawai’i to measure the mass of the planet to fully confirm it.
How will the discovery change the way we think about planet formation?
Following this star and confirming the new exoplanet was the aim of a group of PhD students within the SPECULOOS project.
George Dransfield, one of those PhD students, who recently submitted her thesis at the University of Birmingham, explained: “Under the canonical planet formation model, the less mass a star has, the less massive is the disc of material around that star.
“Since planets are created from that disc, high-mass planets like Jupiter, were widely expected not to form. However, we were curious about this and wanted to check planetary candidates to see if it was possible. TOI-4860 is our first confirmation and also the lowest mass star hosting such a high mass planet.”
Amaury Triaud, Professor of Exoplanetology at the University of Birmingham, who led the study said: “I am ever thankful to the bright PhD students of our team for proposing to observe systems like TOI-4860. Their work has really paid off since planets like TOI-4860 are vital to deepening our understanding of planet formation.
“A hint of what might have happened is hidden in the planetary properties, which appear particularly enriched in heavy elements. We have detected something similar in the host star too, so it is likely that an abundance of heavy elements catalysed the planet formation process.”
About the new exoplanet
The new gas giant takes around 1.52 days to complete a full orbit around its host star. As the host is a cold low mass star, the planet can be referred to as a Warm Jupiter.
A Warm Jupiter is a subclass of planet that holds interest for astronomers looking to learn more about planet formation.
Mathilde Timmermans, another student of the SPECULOOS project, working at the University of Liege in Belgium concluded: “Thanks to its very short orbital period, and to the properties of its host star, the discovery of TOI-4860 b provides a brilliant opportunity to study the atmospheric properties of a warm Jupiter and learn more about how gas giants are formed.”
Future aims of the team
Recently, the team was awarded telescope time at the Very Large Telescope in Chile. They aim to use this to confirm several more planets with similar properties.
