Exoplanets come in all sorts of shapes and sizes, and can be weird in all sorts of ways. There are football shaped exoplanets and exoplanets where it rains gemstones; ones with the density of cotton candy and ones with one lava hemisphere. But new research has uncovered an exoplanet called TIC 241249530 b which is unusual in a different sort of way, as it has one of the most extreme orbits discovered to date.
Most planets don’t have a perfectly circular orbit around their star — including those planets in our solar system — but rather have an orbit that is slightly elongated. The degree of elongation, which astronomers refer to as eccentricity, is measured on a scale of 0 to 1, with 0 being perfectly circular and 1 being extremely stretched. Pluto, for example, has a highly elongated orbit compared to the planets in our solar system and has an orbital eccentricity of 0.25. Earth has an orbital eccentricity of just 0.02.
This new planet, however, has an almost unheard of orbital eccentricity of 0.94. To put it in terms of our solar system, NOIRLab explains that if this planet orbited the sun then it would come 10 times closer to the sun than Mercury does, and also come all the way out to Earth’s orbit. In terms of surface temperature, this would mean moving between a warm summer’s day and hot enough to melt titanium.
That extreme swing in temperature has scientists intrigued, as they want to study what these changes could mean for the planet’s atmosphere.
“We’re especially interested in what we can learn about the dynamics of this planet’s atmosphere after it makes one of its scorchingly close passages to its star,” said one of the researchers, Jason Wright of Penn State. “Telescopes like NASA’s James Webb Space Telescope have the sensitivity to probe the changes in the atmosphere of the newly discovered exoplanet as it undergoes rapid heating, so there is still much more for the team to learn about the exoplanet.”
The researchers are also interested to see how the planet’s orbit develops over time, as they predict that the tidal forces of coming so close to its host star will make the planet’s orbit more circular.
It is a type of planet called a hot Jupiter, which are comparable in size to Jupiter but come much closer to their stars, and that are commonly found outside our solar system. But astronomers still aren’t sure how these planets end up so close to their star, and they think they might form farther out and migrate closer over time. Studying this newly discovered planet could help them answer that.
“While we can’t exactly press rewind and watch the process of planetary migration in real time, this exoplanet serves as a sort of snapshot of the migration process,” said lead researcher Arvind Gupta of NOIRLab. “Planets like this are incredibly rare and hard to find, and we hope it can help us unravel the hot Jupiter formation story.”
