Artist's Illustration of SN 2017ein
Artist's Impression of Progenitor Star to a Type Ic Supernova
This is an artist's concept of a blue supergiant star that once existed inside a cluster of young stars in the spiral galaxy NGC 3938, located 65 million light-years away. It exploded as a supernova in 2017, and Hubble Space Telescope archival photos were used to locate the doomed progenitor star, as it looked in 2007.
The star may have been as massive as 50 suns and burned at a furious rate, making it hotter and bluer than our Sun. It was so hot, it had lost its outer layers of hydrogen and helium. When it exploded in 2017, astronomers categorized it as a Type Ic supernova because of the lack of hydrogen and helium in the supernova's spectrum.
In an alternative scenario (not shown here) a binary companion to the massive star may have stripped off its hydrogen and helium layers.