NASA's TESS Discovers Giant Exoplanet That Has a Mass of Nearly 13 Jupiters and Orbits Its Star in Just 7 Days

Scientists have recently discovered a cosmic cannonball. It is an exoplanet the size of Jupiter but with a mind-boggling density that circles a star 730 light-years away. Astronomers said the exoplanet, called TOI-4603b, has a mass of roughly 13 Jupiters.

It makes it almost three times the density of Earth and slightly more than nine times the density of Jupiter, Science Alert reported. Yet it's pretty close to its star, having an orbital period of only 7.25 days.

Jupiter-like Planet Defying Understanding of Planetary Formation

The team said it places the massive exoplanet in a small but significant category of planets that defy the understanding of the planetary formation and evolution.

Akanksha Khandelwal of the Physical Research Laboratory in India wrote in their research paper, titled "Discovery of a massive giant planet with extreme density around a sub-giant star TOI-4603" available on the preprint server arXiv and accepted for publication in Astronomy & Astrophysics Letters, that it is one of the most massive and densest transiting giant planets ever recorded and valuable addition to the less than five massive ones that require further understanding to know how they formed.

There is a theoretical limit to the amount of mass that a planet can have due to the fact that above a certain critical limit, the temperature and pressure applied to the core are sufficient to start nuclear fusion. The minimal mass at which this process begins in a star is roughly 85 Jupiters, wherein hydrogen atoms begin fusing into helium.

The highest mass limit for a planet is estimated to be between 10 and 13 Jupiters. Brown dwarfs are the things that bridge the distance between them. These planets lack the mass required for hydrogen fusion; nonetheless, their cores may fuse the heavy hydrogen isotope called deuterium, which requires less heat and pressure.

Brown dwarfs are theorized to originate in the same way that stars do, from clumps of molecular clouds that collapse under gravity. They are typically discovered circling stars at a distance of at least five astronomical units (AU) or five times the distance between Earth and the Sun.

12.89 Times More Massive Than Jupiter

NASA's Transiting Exoplanet Survey Satellite (TESS) is dedicated to the hunt for planets outside the Solar System. According to Interesting Engineering, TOI-4603b was studied by a team of astronomers using data from TESS. They found that its radius is 1.042 times greater than Jupiter's and orbits around its star within 7.25 days.

Using radial velocity data, the team was able to decipher the mass of TOI-4603b, which is anticipated to be 12.89 times that of Jupiter. Combining this with the planet's radius resulted in an average density of 14.1 grams per cubic centimeter.

For comparison, the density of the Earth is 5.51 grams per cubic centimeter. Jupiter has a density of 1.33 grams per cubic centimeter. The density of lead is 11.3 grams per cubic centimeter.

But that is not surprising for a brown dwarf, which has an average radius of 0.83 times that of Jupiter. A brown dwarf with a radius of 0.87 times that of Jupiter has a mass of roughly 61.6 Jupiters. They can get substantially denser than TOI-4603b.

Therefore, TOI-4603b still fits most of the criteria to be classified as an exoplanet. But based on the TESS data, it is at the cusp of the brown dwarf mass limit. Its discovery might help scientists in understanding brown dwarfs and giant planets' formation.

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