An article published in “The Astronomical Journal” reports the results of a study of the TOI-421 system, where two exoplanets were discovered following observations conducted by NASA’s TESS space telescope. A team of researchers led by Ilaria Carleo of Wesleyan University used various telescopes to conduct follow-up observations that confirmed the existence of the Neptunian exoplanet detected by TESS also discovering a radial velocity signal that led to the identification of a sub-Neptunian planet. Both are close to their star so they’re heated and their atmosphere is very large with a low density. In particular, the outer exoplanet is of the type that was called super puffy or cotton candy planet, difficult to explain for current models of atmospheric evolution.