M57 is a planetary nebula 2500 light years distant in the constellation Lyra. It was originally discovered by French astronomer Antoine de Pellepoix in 1779.
Like other old red giants M57 has expelled most of its material in the form of hydrogen and oxygen. At its cores lies the white dwarf remnant which consists mainly of carbon. The lighter hydrogen forms the outer reddish envelope while the heavier blue-green oxygen remains about the core. The gases in the expanding shell are illuminated by the radiation of the central white dwarf who’s glow is still 200 times brighter than our Sun.
Normally only M57’s main core is displayed as shown in this older Hubble image: : http://www.waid-obse...-12-HLA-839.jpg
This image was done as a collaboration by myself and Terry Hancock in Michigan. Six one hour narrow-band hydrogen alpha exposures were taken in order to show the dimmer outer shell. The total exposure time was ~25 hours.
Image META information