NGC 40
Properties
Position & Identifiers
Visibility
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Eyepiece View
NGC 40 · 0.8′ · N up, E left
Filter Response Guide
Central Star
Surface Brightness & Observing Difficulty
Survey Image
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About NGC 40
Description
The Bow Tie Nebula (NGC 40) is a planetary nebula in Cepheus, about 3,500 light-years away. Its central star is one of the hottest known, at about 50,000 K, and drives a fast stellar wind that shapes the nebula into its distinctive barrel or bow-tie shape spanning roughly 1 arcminute.
Observing Tips
Requires at least a 4-inch telescope to spot as a fuzzy star. A 6- to 8-inch scope reveals its slightly elongated shape. An OIII filter helps enhance contrast. Best observed in autumn and winter evenings from northern latitudes.
History
Discovered by William Herschel on November 25, 1788. The nebula is notable for its hot central star, which is still in an active mass-loss phase. The name comes from its shape in deep images.
Fun Facts
The central star of NGC 40 is a Wolf-Rayet type star that is rapidly shedding its outer layers. In about 30,000 years, the nebula will have dissipated entirely, and the star will become a white dwarf.