The discovery of this system challenges theories of planetary formation.
Photos from open sources / Artist’s impression of a large planet orbiting a small red dwarf star TOI-5205 / Carnegie Institute of Science
Astronomers have discovered an unusually large planet orbiting a small star located about 280 light-years from Earth. A related study has been published in the Astronomical Journal.
The unusual size of a planet called TOI 5205b has led researchers to call it the “forbidden planet”.
The Jupiter-sized planet was discovered by researchers using NASA’s Transiting Exoplanet Survey Satellite (TESS).
The discovered exoplanet orbits a red dwarf called TOI-5205, which is about 40% the size and mass of the Sun and has a temperature of about 3127 degrees compared to the sun’s average temperature of 5527 degrees.
The dwarf star M is smaller, colder and redder than our sun. These dim stars are among the most common in the universe, and in recent years astronomers have found that M-dwarf stars are more likely to have planets orbiting them.
However, astronomers did not expect such small stars to have giant planets. And that’s exactly what astronomers discovered when they took a closer look at the TOI-5205 planetary system.
“The star TOI-5205 is about four times the size of Jupiter, but it somehow managed to form a planet the size of Jupiter, which is pretty amazing,” said study author Shubham Kanodia of the Carnegie Institute of Science in Washington.
Astronomers have discovered several gas giant planets orbiting old M dwarf stars, but TOI 5205b is the first gas giant discovered around a low-mass M dwarf star.
Because the star is much smaller, the planet looks more like a pea orbiting a lemon, said study lead author Shubham Kanodia of the Carnegie Institute of Science.
Stars form from massive clouds of gas and dust in space. The leftover material from star formation revolves around the star and creates a spinning disk from which planets are born.
“The existence of TOI-5205b expands our knowledge of the disks in which these planets are born,” Kanodia said. “Initially, if there is not enough rocky material in the disk to form the initial core, then it is impossible to form a gas giant planet.”
And, in the end, if the disk evaporates before the formation of a massive core, then it is impossible to form a gas giant planet.
“And yet, TOI-5205b formed despite these limitations. Based on our understanding of planet formation, TOI-5205b shouldn’t exist, it’s some kind of “forbidden planet”.
The researchers are going to observe the planet with the James Webb Space Telescope, which could determine if TOI-5205b has an atmosphere and uncover more mysteries about its formation.
Recent observations “already hint at the presence of more such planets, suggesting that TOI-5205 b, although rare, is not the only one,” Kanodia wrote on his blog.