https://phys.org/news/2018-07-pair-colliding-stars-radioactive-molecules.html

This is the first molecule bearing an unstable radioisotope definitively detected outside of our solar system. Unstable isotopes have an excess of nuclear energy and eventually decay into a stable, less-radioactive form. In this case, the 26-aluminum (26Al) decays to 26-magnesium (26Mg).

"The first solid detection of this kind of radioactive molecule is an important milestone in our exploration of the cool molecular universe," said Tomasz Kamiński, an astronomer with the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., and lead author on a paper appearing in Nature Astronomy.