Four of these experiments — Japan's Super-Kamiokande
, the Sudbury Neutrino Observatory
in Ontario, Italy's Large Volume Detector
, and the Antarctic Muon and Neutrino Detector
at the South Pole — send alerts of possible supernova neutrinos to the SNEWS computer at Brookhaven National Laboratory in New York. Multiple detectors would see a real supernova simultaneously, so SNEWS won't generate false alarms, and the scientists believe neutrinos from supernovae in other galaxies will be too weak for these facilities to detect.
A supernova emits about half its neutrinos in a couple of seconds, while the first electromagnetic signal may not come for many hours or even days, depending on the nature of the star's outer layers and obscuring dust between Earth and the star. So, SNEWS offers the possibility of unprecedented early observation of a supernova's birth. A neutrino signal will accompany all core collapses in the Milky Way, but it's possible a supernova could fizzle, collapsing directly to a black hole without visible fireworks. Such an event would also be of great interest to astronomers. Moreover, says Alex Heger of the University of Chicago, neutrinos from any stellar collapse will help constrain models of stellar interiors — in particular, how fast stellar cores rotate.
SNEWS alerts are issued via e-mail, and Habig encourages amateurs to sign up
for the service. In the best case, neutrino detectors may locate the event only within a few degrees. This means amateurs with wide-field views may be the first to find the supernova and point more powerful telescopes to the event. Very early data taken by amateurs themselves may be of prime importance, too. Because Galactic supernovae are so rare, it will be especially crucial to see the light's very early turn-on.
"Now," says Habig, "we just need to be patient and wait for a star to explode in our own galaxy, close enough to see in neutrinos." A technical paper
on SNEWS has been published in the New Journal of Physics