NGC 2346
planetary nebula in the constellation Monoceros
NGC 2346 is a planetary nebula near the celestial equator in the constellation of Monoceros, less than a degree to the ESE of Delta Monocerotis. It is informally known as the Butterfly Nebula. The nebula is bright and conspicuous with a visual magnitude of 9.6, and has been extensively studied. Among its most remarkable characteristics is its unusually cool central star, which is a spectroscopic binary, and its unusual shape.
The nebular is bipolar in form, with modest outflow velocities in the range of 8–11 km/s, while the center is girded by an expanding belt of molecular gas. The electron density of the nebula is on the order of 400 per cubic centimeter. The ionization of the nebula is the result of ultraviolet emission from the binary companion. The stronger infrared emission from molecular emission is coming from the belt, which is expanding at the rate of 16 km/s. The mass of the molecular gas in the nebula is estimated to be in the range of 0.34–1.85 M☉, and is much greater than the mass of the ionized gas.
The central star is a binary star consisting of an A-type subgiant and a subdwarf O star.
“NGC 2346” enters the record as planetary nebula in the constellation Monoceros. Crown Archives preserves that source wording while asking what planetary, nebula and constellation can confirm, complicate or overturn.
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“NGC 2346” is worth following because a concise public description often conceals a longer documentary argument. Here, planetary, nebula and constellation provides the most credible route into that argument.
Named sources, stable identifiers and responsible institutions provide the strongest route from overview to verifiable evidence. The source revision retrieved here is dated Aug 23, 2026. The linked authority identifier is Q841138. None of the 0 selected statements returned an explicit reference.
The absence of detail may reflect summary conventions rather than a lack of surviving documentation. The source lead contains qualifying language; that uncertainty should survive quotation, summary and reuse. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
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This entry incorporates text from “NGC 2346” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.