Scientists have discovered a giant gas planet orbiting a dwarf star, a rare phenomenon that astrophysicists are struggling to explain.
The star TOI-6894 is similar to many other stars in our galaxy. It is a red dwarf, a small, dim star with a mass only about 20% that of the Sun.
Planetary scientists have long believed that such stars do not provide the necessary conditions for the formation and hosting of giant planets.
But an international team of astronomers has discovered a clear sign of a gas planet orbiting the small star TOI-6894, according to a study published Wednesday in the journal Nature Astronomy.
TOI-6894 is now the smallest star known to host a giant planet.
This star, called TOI-6894b, has a radius slightly larger than that of Saturn, but only half the mass of Saturn. It orbits its star in just 3.36 days.
To discover it, the international team conducted observations using optical data from the Transiting Exoplanet Survey Satellite (TESS), as part of a campaign to search for giant planets orbiting dwarf planets.
TOI-6894b was later confirmed by ground-based telescopes, including the Very Large Telescope in Chile.
"Most stars in our galaxy are small, low-mass stars, like this one, and were previously thought not to host gas giant planets," said study co-author Daniel Bayliss, an associate professor at the University of Warwick in the UK, in a statement. "Thus, the presence of this star has significant implications for the estimated total number of giant planets in our galaxy."
Vincent van Eelen, co-author of the study and a researcher at the Mullard Space Science Laboratory in the UK, explained, "This discovery is puzzling. We don't really understand how a star of such low mass can form such a massive planet! This is one of the goals of exoplanetary searches: by finding planetary systems different from our own, we can test our models and improve our understanding of the formation of our own solar system."
The prevailing theory for planetary fo
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