Astronomers say they have discovered a rogue exoplanet with its own atmosphere in the Neptunian Desert. NGTS-4b, nick-named ‘The Forbidden Planet’ is smaller than Neptune but three times the size of Earth said researchers led by the University of Warwick in the UK.
This area receives strong irradiation from the star, meaning the planets do not retain their gaseous atmosphere as they evaporate leaving just a rocky core. However, NGTS-4b still has an atmosphere of gas. When looking for new planets, astronomers look for a dip in the light of a star — with the planet orbiting it and blocking the light.
The exoplanet, described in the journal Monthly Notices of the Royal Astronomical Society, has a mass of 20 Earth masses, a radius 20 percent smaller than Neptune, and temperature of 1000 degrees Celsius. The Neptunian Desert is the region close to stars where no Neptune-sized planets are found.
However, the NGTS telescopes, situated in the Atacama Desert, Chile, can pick up a dip of just 0.2 percent. Researchers believe the planet may have moved into the Neptunian Desert recently, in the last one million years, or it was very big and the atmosphere is still evaporating.