Science teaches us that stars are much larger than planets, but what about large planets that orbit small stars? This is what a recent study published in Nature Astronomy hopes to address as a team of researchers announced the discovery of a giant planet orbiting a red dwarf star that is approximately 20 percent the mass of our Sun. This study has the potential to challenge longstanding notions regarding the formation and evolution of giant planets and what this could teach us about finding life beyond Earth.
The planet, TOI-6894 b, is located approximately 73.8 parsecs (240.7 light-years) from Earth and is estimated to have a mass of approximately 17 percent of Jupiter. What makes this discovery interesting is that its star is only 20 percent the mass of our Sun, meaning this is the smallest star found to have a planet orbiting it. The conundrum then becomes how did TOI-6894 b form and evolve orbiting such a small star?
“Given the mass of the planet, TOI-6894b could have formed through an intermediate core-accretion process, in which a protoplanet forms and steadily accretes gas without the core becoming massive enough for runaway gas accretion,” said Dr. Edward Bryant, who is a Warwick Astrophysics Prize Fellow at the University of Warwick and lead author of the study. “Alternatively, it could have formed because of a gravitationally unstable disc. In some cases, the disc surrounding the star will become unstable due to the gravitational force it exerts on itself. These discs can then fragment, with the gas and dust collapsing to form a planet.”
Artist’s illustration of TOI-6894 b, which orbits a star that is approximately 20 percent the mass of our Sun. (Credit: University of Warwick/Mark Garlick)
This study comes as the number of confirmed exoplanets has reached almost 6,000, according to NASA, with approximately 30 percent of them being designated as gas giants. Therefore, this study demonstrates that more gas giants orbiting small stars could be discovered in the future while continuing to challenge our understanding of planetary formation and evolution.
What new discoveries about giant planets orbiting small stars will researchers make in the coming years and decades? Only time will tell, and this is why we science!
As always, keep doing science & keep looking up!
Sources: Nature Astronomy, EurekAlert!
