The other is a pulsar, an ultra-dense neutron star left behind when an even more massive star underwent a supernova explosion. (ibtimes.com)
Strangely, though, none of those stars was bigger than about 17 solar masses, even though much more massive stars abound and should also be dying as supernovae. (scientificamerican.com)
Elements heavier than hydrogen and helium were more abundant later in the star - forming boom as more massive stars ended their lives early and enriched the galaxy with material that served as the building blocks of planets and even life on Earth. (sciencedaily.com)