Four years ago, several red giant stars were discovered to pose a paradox: even though they are built from very old stellar material, their large masses indicate a clearly younger age. Scientists from the Max Planck Institute for Solar System Research (Germany), Aarhus University (Denmark), and The Ohio State University (U.S.) have now solved the apparent contradiction. For the first time, they investigated the abundances of carbon, nitrogen, and oxygen swirled from the nuclei of these stars to their surfaces. This allows for an indirect look at processes deep within. Several of the investigated red giants must have merged with others during an advanced stage of stellar evolution, the researchers conclude. In these cases, mass is not a suitable criterion for age determination; the stars are indeed old.
* This article was originally published here
