Supernovae are the ultimate variable stars. In distant galaxies, a previously indistinguishable star that ends its life in a supernova explosion may outshine its host galaxy in a spectacular blaze of glory. A visible supernova in our own galaxy is an exciting and ultimately historic event. Kepler’s supernova of 1604 subtly changed the course of scientific and Western cultural history. The nearby supernova SN1987A yielded a treasure trove of scientific information, still being studied after 30 years. The immense public interest in a possible Galactic supernova was seen during the great dimming of Betelgeuse (2019) in which AAVSO observations were of critical importance.
Supernovae are both tools and “laboratories” for modern astronomy and astrophysics. Type Ia supernovae are a standard candle for measuring the distances to far away galaxies and of astrophysical interest themselves. A core-collapse supernova (CCSN; Type II and others) is an important process by which heavy elements are created and scattered through the interstellar medium from which other stars and planets may form. They also create neutron stars and black holes. The scientific study of supernovae is hindered by the inability to precisely predict when a star will explode. Important information may only be found by studying the earliest moments of the light curve.
Nearby CCSN are of special scientific interest. However, they are very rare, perhaps occurring two to three times per century, often invisible to the naked eye. Therefore, the world’s scientific community is preparing for the next once-in-a-lifetime event.
Although the time of a supernova event cannot be predicted, an early alert system is operational that gives an alert of a CCSN in our galaxy or a nearby dwarf galaxy minutes to hours before for visible light reaches earth. The SuperNova Early Warning System (SNEWS) is a collaboration of particle physics experiments that detect the burst of neutrinos produced by the core-collapse process. These neutrinos leave the star at almost the moment of core collapse while other electromagnetic radiation escapes the dying star minutes to hours later, depending on the astrophysical details.
The SNEWS alert has been made available to prepare the astronomy community (professional and amateur) and the public for the imminent light from the SN. To sign up for the alert, find the sign up form on the website.
Recently, SNEWS and teams from the AAVSO collaboration have begun work together on several projects to prepare for the next galactic supernova. One project is to obtain long-term photometry on stars in the Milky Way that are candidates for core-collapse supernovae. These measurements could be of great scientific interest. While it is not likely that the light curves could predict an impending SN, after the fact the light curves of the star that actually explodes would yield unique and important scientific information.
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