Astronomers believe they’ve found one of the most unique exoplanets to date, a strange distant alien world which is shaped like an American Football. The odd exoplanet’s shape may be due to powerful gravitational forces it experiences near its star. Called KOI 1843.03, this world orbits a red dwarf star with just under half the mass of our sun and is about 395 light-years away. Previous research found that KOI 1843.03 had approximately 44% of Earth’s mass and 60% of Earth’s diameter.
Previous studies suggested that KOI 1843.03 orbits its star closer than any other planet known so far.”Whizzing around its star in only 4.245 hours, a ‘year’ for this planet is just over one-sixth of a day on Earth,” Leslie Rogers, an astrophysicist at the University of Chicago and the senior author of the new research, told Space.com.
In a previous paper focusing on KOI 1843.03, Rogers and her colleagues discussed the possible consequences of the powerful gravitational forces that the planet is likely to experience from its near orbit. Those forces are essentially an extraordinarily strong version of the tidal forces that Earth experiences from the Moon. In that study, scientists suggested that the exoplanet must be made primarily of iron to avoid being crushed by the gravity. While Earth has approximately 32% iron, they estimated that KOI 1843.03 is composed of around 66% iron.
“KOI 1843.03 is one of the most iron-enhanced exoplanets discovered to date,” Rogers said.
Scientists knew of a handful of iron-rich “cannonball” planets, such as Mercury in our own solar system, which is about 70% iron. To see what effects an extreme orbit like KOI 1843.03 could have in such a world, the researchers conducted the first 3D simulations of the inner structures of rocky planets whose ultra-tiny orbits would generate tidal distortions.
Scientists found that KOI 1843.03 is probably shaped like an American football.
“KOI 1843.03 is the most aspherical exoplanet discovered to date,” Rogers said. “Our models show that KOI 1843.03 is significantly elongated along the direction toward its star, having an aspect ratio of up to about 1.8.”
The researchers noted that of the nine exoplanets whose orbits last less than a day for which the researchers have good estimates of density, four appear rich in iron. But such planets could be more spherical than iron-poor worlds in the same orbits.
“We expect that more iron-rich compositions will lead to less distorted planets,” Ellen Price, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics in Massachusetts and the lead author on the new research, told Space.com. “There is a trade-off between how extreme the shape of the planet is and how extreme its composition is.”