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Abell 7 is a faint planetary nebula located 1800 light-years away in the constellation of Lepus. It has a generally spherical shape about 8 light-years in diameter. Within the sphere are complex details that are brought out by narrowband filters. Abell 7 is estimated to be only 20,000 years old, but the central star, a fading white dwarf, is estimated to be some 10 billion years old.
APOD (5 December 2013), Robert J. Nemiroff (MTU); Jerry Bonnell (USRA) (eds.), Abell 7, NASA, Very faint planetary nebula Abell 7 is some 1,800 light-years distant, just south of Orion in planet Earth's skies in the constellation Lepus, The Hare. Surrounded by Milky Way stars and near the line-of-sight to distant background galaxies, its generally simple spherical shape, about 8 light-years in diameter, is outlined in this deep telescopic image. ... Abell 7 itself is estimated to be 20,000 years old. Its central star is seen here as a fading white dwarf some 10 billion years old.
Abell, George O. (1955), "Globular Clusters and Planetary Nebulae Discovered on the National Geographic Society-Palomar Observatory Sky Survey", Publications of the Astronomical Society of the Pacific, 67 (397): 258, Bibcode:1955PASP...67..258A, doi:10.1086/126815
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