The particles that make up comets began life as the dying breaths of previous generations of stars. (discovermagazine.com)
«These are grains from previous generations of stars,» says coauthor Gerald Wasserburg, a geochemist and Crafoord laureate at Caltech. (sciencemag.org)
The second process relies on the fact that stars also contain smaller amounts of carbon produced in previous generations of stars that exploded as supernovas. (insidescience.org)