Tiny star hosts giant surprise: Saturn-sized planet found orbiting red dwarf star

Artististic impression of TOI-6894b Exoplanet (Image: University of Warwick/Mark Garlick)

The universe never ceases to amaze. Astronomers have now found a giant planet circling a star so small, it once seemed impossible. This rare find challenges what we thought we knew about planets and stars — and could mean there are more hidden giants out there.

A Giant World Around a Tiny Star

The star, named TOI-6894, is a red dwarf. It has only 20% the mass of our Sun. Until now, experts believed stars this small couldn’t hold big planets. But a new discovery has changed that idea completely.

The giant planet, named TOI-6894b, was spotted using NASA’s Transiting Exoplanet Survey Satellite, or TESS. The work was led by Dr Edward Bryant of UCL’s Mullard Space Science Laboratory. His team was searching for big planets around small stars.

The planetary nature of the signal was later confirmed. Several telescopes helped check the data. These included instruments from the SPECULOOS and TRAPPIST projects. Both projects are led by the University of Liège.

Dr Khalid Barkaoui, a researcher on both teams, led the follow-up studies. “The transit signal was clear in our data,” he said. “Our checks ruled out every other cause. The only option left was a Saturn-like planet. It orbits its star every three days.”

Later observations confirmed the planet’s mass. It’s half that of Saturn, which makes it a true giant. TOI-6894 is now the smallest star ever found with a planet this large.

Rewriting What We Thought We Knew

This changes how scientists understand planets and how they form. Before this, no one thought stars so small could grow or hold on to big planets. Stars like TOI-6894 are very common across the galaxy. This suggests there may be many more giant planets than we believed.

Prof. Jamila Chouquar was working at ULiege when this was discovered. She explained, “We didn’t think tiny stars could do this. Now we know they can, and there may be many more out there.”

Planet Formation Theories Under Pressure

Current planet theories say giant worlds are rare around small stars. That’s because the material around them during formation is limited. These stars don’t usually have enough dust or gas to form big planets.

Dr Mathilde Timmermans, from the SPECULOOS team, shared her thoughts. “This planet doesn’t match what models predict,” she said. “There’s no good explanation yet. It means we’re missing something. That’s why we need to find more planets like this.”

Dr Timmermans now leads a new study called MANGO. She runs it with Dr Georgina Dransfield at the University of Birmingham. The project is part of the SPECULOOS programme and aims to hunt for more odd worlds.

Prof. Michaël Gillon, research director at ULiege and head of SPECULOOS and TRAPPIST, said, “This planet shows us how much variety exists. Our galaxy has more surprises waiting. Most of our targets are similar stars, or even smaller. So we may find more like this soon.”

The find was published in Nature Astronomy, and it may help rewrite the rulebook on how planets form — and where.