Gary Imm

GaryI

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A backyard amateur astrophotographer enjoying retirement with my wife on beautiful Lake Livingston in Onalaska, Texas, about 90 minutes north of Houston.

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About 10% of PNe are believed to be spherical. Because of the symmetry, the progenitor in these cases is believed to be a single star (no companion). Although this subject is still being debated, it is believed that single stars do not have the required rotational speeds late in their life to form the bipolar and elliptical PNe described further below. Spherical PNe have no internal structure, a faint (if any) rim, and a circular projection. The inner region can either be clear or somewhat occluded.