The very first light emitted by a supernova was captured by an amateur astronomer in a serendipitous series of observations. This never-before-seen look at a supernova is what researchers were waiting for and they've now captured the cosmic explosion in a series of photographs. The discovery and the follow-up observations are published in Nature.
On September 20, 2016, Victor Buso was testing his new camera by taking a picture of NGC 613, which is about 80 million light-years from Earth. Over the course of 90 minutes, he took several 20-second time-lapse photographs, and that’s when the light from the supernova reached Earth.
Buso examined the images immediately and contacted Melina Bersten and her colleagues at the Instituto de Astrofísica de La Plata in Argentina, who spread the word to colleagues around the world. Suddenly, observatories like the Lick and the Keck were pointing their instruments at this newly found event.
"Professional astronomers have long been searching for such an event," co-author and UC Berkeley astronomer Alex Filippenko, who followed up the discovery, said in a statement. "Observations of stars in the first moments they begin exploding provide information that cannot be directly obtained in any other way."
The “first light” of a supernova conveys a huge amount of information about the nature of the progenitor star. Based on Buso's observations and theoretical models, astronomers estimated that the star behind the explosion, technically called SN 2016gkg, was originally 20 times heavier than the Sun. However, by the time it went boom, it was only 5 solar masses. They suspect a companion might have been stealing the material.
Thanks to the observations by Buso, the researchers estimate that the luminosity of the object increased at a dramatic rate of 40 magnitudes per day. The increase didn’t last for a full day, but it's still remarkable. It’s a bit like if something as faint as Pluto (not visible to the naked eye) suddenly became as bright as the Sun in the sky over 24 hours.
"Buso's data are exceptional," Filippenko added. "This is an outstanding example of a partnership between amateur and professional astronomers."
Dr Bersten also noted how lucky Buso was to capture such an event. She estimated that the chances of capturing such an event were around the order of one in 10 million, or potentially even lower at one in 100 million. Pretty much like winning the lottery.