Supernova 2016gkg at NGC 613. Color image obtained on February 18, 2017 at the 1-meter Swope telescope
Good pictures from an amateur astronomer from Argentina helped to get a first look at the initial burst of light from the explosion of a massive star. During testing, Viktor Buso photographed a distant galaxy before and after the appearance of a supernova. This moment is called a shock breakthrough - when a supersonic pressure wave from an exploding stellar core hits and heats the gas to high temperatures, causing it to glow.
At the moment, nobody has been able to do this, because the stars explode by chance and it is incredibly difficult to catch an event. New data provide valuable information about the physical structure of the star before the catastrophic death and the nature of the explosion itself.
The explosion was named SN 2016gkg. Testing the camera Buso conducted on September 20, 2016 on a 16-inch telescope, tracking the territory of the spiral galaxy NGC 613. It is 80 million light-years distant from us and lives on the territory of the Sculptor. Fortunately, I immediately reviewed the frames and noticed that the bright point rapidly increased the glow towards the end of the spiral arm, which was not noticeable in the first image. Soon, other astronomers found out about this and realized that the amateur had managed to catch a rare event - part of the first light from a massive exploding star.
Professional scientists took up further observations, who for 2 months carefully studied the object, revealing data on the type of star and the nature of the explosion. They managed to get a series of 7 spectra in the 3-meter telescope of the University of California and in the 10-meter telescope of the Keck Observatory.
It turned out that we are talking about a type IIb supernova — an explosion of a massive star that lost most of its hydrogen envelope. Combining information with theoretical models, the team found that the initial mass was 20 times more solar. But due to the loss, it decreased to 5 solar masses.