Flavor of a Dying Star

NASA/ESA/P. Jefferies (STScl) Illustration of the stages of a dying star as it collapses into a black hole. A core-collapse supernova occurs when a massive star reaches the end of its life. After running out of hydrogen and other light elements to burn, the star makes a last ditch effort to counter gravity, fusing ever heavier elements at an ever faster pace. Eventually it reaches the point where heavy fusion extracts energy from the core rather than adds it. The core rapidly contracts, then recoils. The resulting explosion rips the star apart and briefly outshines an entire galaxy. But not all giant stars end with a bang. Some of them experience a core collapse so quick and dense that the core squeezes itself into a black hole. These stars end with a whimper rather than a bang. So what exactly causes this difference? Why do some stars explode and others not? What key features distinguish between the two? The answer could lie in an aspect of neutrinos known as flavor. Neutrinos are…