Terbium, a rare earth metal聽that belongs to the lanthanoids, has been detected on KELT-9, the galaxy鈥檚 hottest exoplanet, which orbits its聽distant star聽about 670聽light years聽from earth.
In a in the journal Astronomy & Astrophysics, Lund University researchers explain that this discovery is exciting because it is the first time terbium is found in an exoplanet鈥檚 atmosphere.
鈥淲e have developed a new method that makes it possible to obtain more detailed information. Using this, we have discovered seven elements, including the rare substance terbium, which has never before been found in any exoplanet鈥檚 atmosphere,鈥� Nicholas Borsato, lead author of the study, said in a media statement.
Terbium was discovered in 1843 by the Swedish chemist Carl Gustaf Mosander in the Ytterby mine in the Stockholm archipelago. The substance is very rare in nature, and 99% of the world鈥檚 terbium production today takes place in the Bayan Obo mining district in Inner Mongolia.
鈥淔inding terbium in an exoplanet鈥檚 atmosphere is very surprising,鈥� Borsato said.
Most聽exoplanets聽are discovered by astronomers making measurements of how brightly stars shine. When an exoplanet passes in front of its star, the star鈥檚 brightness decreases. Thanks to their advanced measurement method, the researchers at Lund have succeeded in filtering out the dominant signals in KELT-9 b鈥檚 atmosphere. This opens up the possibility of finding out more about the atmospheres of other exoplanets.
鈥淟earning more about the heavier elements helps us, among other things, to determine the age of the exoplanets and how they were formed,鈥� Borsato noted.
Exoplanets, or聽extrasolar planets, are planets that are in other solar systems than our own. The first confirmed discovery was made in 1992, of an exoplanet orbiting a neutron star. Three years later, the first exoplanet with a sun-like star was discovered. Since then, over 5,000 exoplanets have been recorded. The existence of exoplanets often raises questions about the possibility of life elsewhere in the universe.
鈥淒etecting聽heavy elements聽in the atmospheres of ultra-hot exoplanets is another step towards learning how the atmospheres of planets work. The better we get to know these planets, the greater chance we have of finding Earth 2.0 in the future,鈥� Borsato said.