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Astronomers have discovered an unusually large planet orbiting a small star, located about 280 light years from Earth.
The unexpected size of the newly discovered world, known as TOI 5205b, has led researchers to call it the “forbidden planet”.
About the size of Jupiter, it was spotted by researchers using NASA’s Transiting Exoplanet Survey Satellite, or TESS. Jupiter is the largest planet in our solar system.
The planet-hunting mission, launched in 2018, surveys the light of the nearest and brightest stars to see dips in the starlight, which suggest planets orbiting those stars. The TESS mission has discovered thousands of potential planets.
The exoplanet orbits a red dwarf star called TOI-5205, which is about 40% the size and mass of our Sun, and about 5,660 degrees Fahrenheit (3,127 degrees Celsius) in temperature compared to the Sun’s average flare of 9,980 F (5,527 C).
An M dwarf star is smaller, cooler and redder than our sun. These faint stars are some of the most common in the universe, and in recent years, astronomers have discovered that M dwarf stars are more likely to be orbited by planets.
But astronomers didn’t expect such small stars to host giant planets – and that’s exactly what they found when they took a closer look at the TOI-5205 planetary system.
The results were studied published on Tuesday in the Astronomical Journal.
“The host star, TOI-5205, is only about four times the size of Jupiter, but it managed to form a Jupiter-sized planet, which is surprising.,” study author Shubham Kanodia, a postdoctoral fellow at the Carnegie Institution for Science in Washington, DC, said in a statement.
Astronomers have discovered several gas giant planets orbiting older M dwarf stars, but TOI 5205b is the first gas giant to be found around a low-mass M dwarf star.
The researchers compared the planet to a pea going around a lemon. In our solar system, Jupiter could be compared to a pea orbiting a grape (standing in our sun).
When TOI 5205b crosses in front of its star during orbit, the planet blocks 7% of its light.
The discovery of the planetary system challenges theories of planet formation.
Stars form from giant clouds of gas and dust in space. The material left over from star formation swirls around the star and forms a rotating disk where planets are born.
“The existence of TOI-5205b adds to what we know about the disks in which these planets are born,” Kanodia said.
“First, if there is not enough rocky material in the disk to form the initial core, one cannot create a gas giant planet. And at the end, if the disk evaporates away before the giant core is formed, then one can not form a gas giant planet. And yet TOI-5205b was formed despite these guardrails. Based on our current nominal understanding of planet formation, TOI-5205b should not exist; it is a ‘forbidden’ planet.”
Researchers are looking to observe the planet in the future using the James Webb Space Telescope, which could detect TOI-5205b It has an atmosphere and will release more of the secrets of how it is done.
Data collected by the Habitable Zone Planet Finder on the 10-meter Hobby-Eberly Telescope at the University of Texas at Austin’s McDonald’s Observatory shows the potential for future discoveries, according to the research team.
Observations “already indicate the existence of more such planets, suggesting that TOI-5205 b — while certainly an outlier — is not the only one,” Kanodia wrote in a blog post.
