Abell 78
This planetary nebula has the unusual property of having a faint outer halo composed of normal stellar material (mostly hydrogen) and a bright inner elliptical ring composed mostly of helium. The helium ring provides direct confirmation that hydrogen is being converted to helium in the centers of stars and can later be ejected back into the galaxy's pool of gas for building another generation of enriched stars.
Shape: bright central zones and faint extended outer halo
Location: Cygnus constellation
RA: 00 40 33.00 DEC: +26 44 30.0
Abundances/Description: The outer halo is composed mostly of Hydrogen. The bright inner elliptical ring is composed mostly of Helium.
Discoverer: George Abell - (1966)