Scientists Puzzled By Giant Planet Orbiting Tiny Star

Astronomers have uncovered a cosmic phenomenon that defies traditional theories of planetary formation: a giant planet orbiting an unusually small star. The star, named TOI-6894, is located roughly 240 light-years from Earth in the constellation Leo. Remarkably, it hosts a massive exoplanet, TOI-6894 b, comparable in size to Saturn, the second largest planet in the solar system.

The phenomenon which confused the scientist is that TOI-6894 is a red dwarf star – the smallest known star to host a large planet. It is approximately 40% smaller than the two previous record-holding stars. "The question of how such a small star can host such a large planet is one that this discovery raises – and we are yet to answer," said astronomer Edward Bryant of the University of Warwick in England.

According to the standard rule of planetary formation, stars and their planets form from the collapse of their molecular cloud – large regions of gas and dust. As the central star forms, the remaining material flattens into a protoplanetary disk, from which planets eventually develop. Smaller molecular clouds generally form smaller disks, which contain less material, making the formation of giant planets around tiny stars highly impossible.

While no known planet is larger than its host star, in this case, the size difference is unusually small. The sun's diameter is 10 times larger than Jupiter, but TOI-6894's diameter is just 2.5 times larger than its only known planet. "Given these stars are very common, there may be many more giant planets in the galaxy than we thought," Bryant noted.