CCS: Astrophysics: About Us: Core collapse supernovae

Why Study Core Collapse Supernovae?

Most Energetic Explosions in the Cosmos

Core collapse supernovae are spectacular stellar explosions that mark the end of a star's life after millions to billions of years of evolution, disrupting it amost entirely. They occupy a special place in the cosmic hierarchy for many reasons. Among them, they are among the most energetic explosions in the cosmos. The energy release occurs as a central "neutrino bulb" radiates neutrinos at the staggering rate of 10 billion, billion, billion, billion, billion Watts! Neutrinos, like photons, are massless (or very light) particles of radiation. They come in three "flavors": electron, muon, and tau neutrinos, and each neutrino flavor has an "antineutrino." The radiation heating from this central neutrino bulb is thought to power the supernova shock wave that drives the explosion.

Source of Most Elements in the Universe

Core collapse supernovae are responsible for disseminating and producing most of the elements in the Universe. Elements heavier than helium are synthesized in stars during the course of stellar evolution, and when a star ends its nuclear burning life and is disrupted in a few hours in a supernova explosion, these elements are disseminated into the interstellar medium to be postprocessed later in other stars, solar systems, or other astrophysical systems. In addition to disseminating elements formed during stellar evolution, supernovae play a key role in synthesizing new heavy elements. In the "neutrino-driven wind" that emanates from the proto-neutron star left behind after the star explodes, transiron elements are synthesized by a "rapid neutron capture" or "r" process. Additional nucleosynthesis occurs via "neutrino nucleosynthesis," also known as the "Nu" process, during which neutrinos emanating from the proto-neutron star interact with nuclei in the stellar core to produce new nuclei.

Birth of Neutron Stars and Black Holes

While they signal stellar death, supernovae also signal the birth of neutron stars and black holes. These important and enigmatic astrophysical objects form from the cooling postsupernova remnant and are the basic building blocks of other astrophysical systems. Pulsars, which are rotating neutron stars, and x-ray binary systems, which are composed of accreting black holes and their stellar companions, are among many important examples.

"Holy Grail" of Astrophysics

Because of their astrophysical and cosmological importance, and because modeling core collapse supernovae and supernova nucleosynthesis will require the Herculean task of accurately simulating multidimensional radiation transport and hydrodynamics, the quest for a solution to the supernova problem has been dubbed the quest for the astrophysics Holy Grail, which has eluded research efforts for more than three decades. Now, (a) with the myriad observations from the IMB neutrino detector in the old Morton salt mine in Ohio, the Kamiokande neutrino detector in Japan, the Hubble Space Telescope, the Compton Gamma Ray Observatory, the International Ultraviolet Explorer, and other ground-based and space-based facilities, (b) with the promise of hundreds to thousands of neutrino detections of all three flavors in the next-generation detectors SNO in Sudbury, Canada and Super-Kamiokande in Japan, for the next galactic supernova, (c) with an ever increasing understanding of the ingredients that play a key role in the supernova mechanism, and (d) with the computing power afforded by vector and massively parallel supercomputers, we are presented with a unique opportunity to finally solve one of Nature's most important problems, and in so doing, take a big step toward understanding how life as we know it became possible.