According to a January 22 news release from the University of London Observatory, students and staff have discovered one of the closest supernova to Earth in the last few decades. On January 21 at 19:20 GMT, a team of students – Ben Cooke, Tom Wright, Matthew Wilde and Guy Pollack – assisted by Dr. Steve Fossey, observed the exploding star in nearby galaxy Messier 82, also known as the Cigar Galaxy.
The accidental discovery occurred during a 10-minute telescope workshop for undergraduate students that led to a global clamber to acquire confirming images and spectra of a supernova in one of the most unusual and interesting of our neighboring galaxies.
“The weather was closing in, with increasing cloud, so instead of the planned practical astronomy class, I gave the students an introductory demonstration of how to use the CCD camera on one of the observatory’s automated 0.35–meter telescopes,” Fossey said.
The students selected M 82, a bright and camera-friendly galaxy as their target, as it was in one of the dwindling patches of clear sky. While fine-tuning the telescope’s position, Fossey noticed a “star” superimposed on the galaxy which he did not recognize from previous observations.
The nontraditional team of astronomers inspected online archive images of the galaxy, and it became obvious that there was, indeed, a new star-like object in M 82. With clouds approaching fast, there was hardly time to check, so the team switched to taking a rapid series of 1 and 2 minute exposures through different colored filters to ensure that the object persisted, and to be able to measure its brightness and color.
In the meantime, the team started up a second telescope to acquire a second source of data, to ensure the “star” was not an instrumental object. By approximately 19:40 GMT, the cloud cover was almost complete, but it was just possible to make out the new object in the second data set.
As there were no online reports of any prior sightings of this object, it seemed clear that this was a new fleeting source, such as a supernova. It was vital to move quickly to alert astronomers worldwide to confirm the discovery, and most importantly, to obtain a spectrum of the supernova. This latter action would confirm whether it was a supernova.
Fossey organized a report for the International Astronomical Union’s Central Bureau for Astronomical Telegrams, the organization that catalogs supernovae. He also notified a U.S.-based supernova search team that has access to spectroscopic facilities.
Spectra collected by astronomers at other telescopes around the world suggest that it is a Type Ia supernova, triggered by a white dwarf star pulling matter off a larger neighboring star until it becomes unstable and explodes.
The supernova is one of the closest to be observed in recent decades, with the closest by far since the invention of the telescope being Supernova 1987A in February 1987, located at a distance of 168,000 light years.