How Do Exoplanets Get So Big And So Hot?

Hot Jupiters are giant gas exoplanets that orbit around their host stars. Even though their names might suggest otherwise, they’re a lot bigger and hotter than Jupiter.

According to a report from the University of Arecibo, 740 of the 3,442 exoplanets that exist are Hot Jupiters. These giant exoplanets are pretty interesting, and some of them are so big, they defy the theories of planetary formation. But, there’s new research tht shows that Hot Jupiters actually aren’t that big, they just expand over time.

The Hungarian Automated Telescope Network in Arizona and Hawaii has allowed scientists to identify two Hot Jupiters. HAT-P-65b and HAT-P-66b are their names, and they are 2,745 and 3,025 lighyears from Earth, respectively. Each of the exoplanets orbit their stars 10 times closer than Mercury’s distance from our sun.

Scientists compared the two exoplanets to 200 others, and they found that both are abnormally large for their ages. They hypothesized that, because they orbit so close to their stars, they end up with tons of radiation, and expand sort of like a pufferfish.
The lead author of the study, Joel Hartman, suggested that the research could shed light on the intriguing giants. Some of them are up to twice Jupiter’s size, but that goes against the researcher’s models, which shows that they could only reach 1.5 times the size of Jupiter. They’re on really inclined orbits relative to those of their hosts, and some are even on a backwards orbit.
According to Hartman and his team, it isn’t that unusual that HAT-P-65b and HAT-P-66b have grown to diameters of 1.9 and 1.6 times Jupiter’s. Both exoplanets are almost 80 percent through their lives. Before stars die, they usually burn brighter and emit radiation, causing expansion.

All of this information has been available as a possible explanation for the size Hot Jupiters can reach for a while. But until now, no one has been able to demonstrate how the exoplanets are able to move their energy to their interiors and expand.

This study has not only shed a lot of light on Hot Jupiters. It’s also helping us understand how radiation can impact a planet’s evolution. All of the information gathered by Hartman and his team will mean more thorough studies of other exoplanets.

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