An international group of researchers has made a surprising discovery: a Jupiter-sized planet called TOI-4860 b orbiting a small star in the Corvus constellation.
The existence of this ‘warm Jupiter’ defies current understanding of planet formation because such a small star isn’t expected to host a planet of Jupiter’s size.
Furthermore, both the planet and its star appear to be unusually rich in heavy elements.
The research, led by astronomers from the University of Birmingham, has been published in the Monthly Notices of the Royal Astronomical Society.
The planet was initially spotted using NASA’s Transiting Exoplanet Survey Satellite due to a decrease in brightness when the planet transited its star. However, the data was insufficient to confirm the planet’s existence.
To validate the planet, the team used the SPECULOOS South Observatory in Chile to measure the planetary signal across multiple wavelengths.
They also noticed that there was no change in light just before and after the planet disappeared behind its star, suggesting the planet was not emitting light.
The team worked with a group in Japan using the Subaru Telescope to measure the planet’s mass, fully confirming its existence.
The researchers who confirmed the planet were a group of Ph.D. students working on the SPECULOOS project.
One of these students, George Dransfield, explained, “Under the canonical planet formation model, the less mass a star has, the less massive is the disc of material around that star…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 and the study’s leader, thanked the students for their work, highlighting the importance of planets like TOI-4860 b for understanding planet formation.
The ‘warm Jupiter’ completes a full orbit of its star in 1.52 days. While this is fast, the star itself is quite cool, so the planet is not overly hot.
This characteristic makes it a subject of great interest for astronomers looking to understand how such planets form.
Mathilde Timmermans, a student involved in the SPECULOOS project, noted, “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.”
The team has now been granted time with the Very Large Telescope in Chile, which they plan to use to confirm the existence of several more similar planets.
The study was published in the Monthly Notices of the Royal Astronomical Society.
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Source: University of Birmingham
