English: The subject of this NASA/ESA Hubble Space Telescope Picture of the Week is the spiral galaxy NGC 337, located about 60 million light-years away in the constellation Cetus (The Whale). This image combines observations made at two wavelengths, highlighting the galaxy’s golden centre and blue outskirts. The golden central glow comes from older stars, while the sparkling blue edges get their colour from young stars. If Hubble had observed NGC 337 about a decade ago, the telescope would have spotted something remarkable among the hot blue stars along the galaxy’s edge: a brilliant supernova. The supernova, named SN 2014cx, is remarkable for having been discovered nearly simultaneously in two vastly different ways: by a prolific supernova hunter, Koichi Itagaki, and by the All Sky Automated Survey for SuperNovae (ASAS-SN). ASAS-SN is a worldwide network ofrobotic telescopes that scans the sky for sudden events like supernovae.  Researchers have determined that SN 2014cx was a Type IIP supernova. The “Type II” classification means that the exploding star was a supergiant at least eight times as massive as the Sun. The “P” stands for plateau,meaning that after the light from the supernova began to fade, the level reached a plateau, remaining at the same brightness for several weeks or months before fading further. This type of supernova occurs when a massive star can no longer produce enough energy in its core to stave off the crushingpressure of gravity. SN 2014cx’s progenitor star is estimated to have been ten times more massive than the Sun and hundreds of times as wide. Though it has long since dimmed from its initial brilliance, researchers are still keeping tabs on this exploded star, not least through the Hubble observing programme which produced this image. [Image Description: A barred spiral galaxy on a dark background. The galaxy’s central region is a pale colour due to older stars, contains some pale reddish threads of dust, and is brighter along a broad horizontal bar through the very centre. Off the bar come several stubby spiral arms, merging into the outer region of the disc. It is a cool blue colour and contains some bright sparkling blue spots, both indicating young hot stars.]

Credit:

ESA/Hubble & NASA, C. Kilpatrick