NGC 40 -- Bow-Tie Planetary Nebula in Cepheus
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Bow-Tie Nebula
NGC 40 is an interesting Planetary Nebula high in the northern sky. Instead of a dim white dwarf
star at its center it has a blazing Wolf-Rayet star. The central star is bright, and the dimmer
low-excitation nebula hugs it tightly. Under low power the nebula is overpowered by the central
star and will avoid detection in a telescope. Up the magnification and the nebula slowly forms
around the star. Because of its unusual nature, a UHC nebula filter works better than the OIII
nebula filter. But I found that the nebula was easily visible without any nebula filter in the
110mm refractor.
In the small refractor, little detail can be teased out of the nebula. It appears as a small
semi-circular nebula with a bright star at its center. In larger telescopes NGC 40 appears more
rectangular shaped with embedded bright arcs and knots in the nebula; somewhat resembling a
bow-tie.
star at its center it has a blazing Wolf-Rayet star. The central star is bright, and the dimmer
low-excitation nebula hugs it tightly. Under low power the nebula is overpowered by the central
star and will avoid detection in a telescope. Up the magnification and the nebula slowly forms
around the star. Because of its unusual nature, a UHC nebula filter works better than the OIII
nebula filter. But I found that the nebula was easily visible without any nebula filter in the
110mm refractor.
In the small refractor, little detail can be teased out of the nebula. It appears as a small
semi-circular nebula with a bright star at its center. In larger telescopes NGC 40 appears more
rectangular shaped with embedded bright arcs and knots in the nebula; somewhat resembling a
bow-tie.