“But very red!” he wrote in an email. “I still remember that exclamation point” in the Great Magellanic Cloud.
According to astronomers, there are three possible lots for a star that is out of fuel and died. It can end up as a hot dense cinder called a white dwarf, as an even hotter and denser neutron star or as a black hole, depending on the initial mass and other details about its composition.
The exploding star was later identified as a giant blue star known as Sanduleak -69 ° 202, which immediately disappeared from the sky. In its prime, it was about 19 times as massive as the Sun, which puts astronomers in the range of producing a neutron star.
Reinforcing that belief was the subsequent discovery that two or three hours before the supernova was discovered, a pulse of two dozen lightweight subatomic particles called neutrinos splashed into particle detectors on Earth. Messages from inside the inferno, they had extinguished the visible light when escaping the collapsing star.
“Neutrinos are indeed the key to the process of supernovae and neutron stars,” said Drs. Burrows.
As a massive star like this undergoes its thermonuclear implication, he observed, it develops onionskin layers of helium, oxygen, carbon and other new coin forms. At its center is a growing core of iron, the most stable element. When it reaches a limit, called the Chandrasekhar limit, at which atomic forces can no longer support its weight, it implodes and rebounds, leaving a warm, dense neutron star.
A shock wave ripples through the layers. Accompanying it, and forcing it through absorbing heat, are abundant amounts of neutrinos, generated from the energy of the collapse. Indeed, 99 percent of a supernova’s energy goes into these particles and out into the cosmos.
Neutrinos are famous for their spooky ability to pass through solid lead such as moonlight through glass, but even neutrinos have trouble escaping the nucleus of a dense proto-neutron star. It is the energy provided by neutrinos, astronomers think, that provides the oomph to blow the star apart. If the neutrinos cannot rise fast enough to heat up an explosion, the supernova will likely fizzle and the newborn neutron star will fall into a black hole, said Drs. Burrows.
