Winnecke 4 (also known as Messier 40 or WNC 4) is an optical double star consisting of two unrelated stars in a northerly zone of the sky,

Ursa Major Ursa Major (; also known as the Great Bear) is a constellation in the northern sky, whose associated mythology likely dates back into prehistory. Its Latin name means "greater (or larger) bear," referring to and contrasting it with nearby Ursa ...

. The pair were discovered by

Charles Messier Charles Messier (; 26 June 1730 – 12 April 1817) was a French astronomer. He published an astronomical catalogue consisting of 110 nebulae and star clusters, which came to be known as the ''Messier objects''. Messier's purpose f ...

in 1764 while he was searching for a nebula that had been reported in the area by

Johannes Hevelius Johannes Hevelius Some sources refer to Hevelius as Polish: * * * * * * * Some sources refer to Hevelius as German: * * * * *of the Royal Society * (in German also known as ''Hevel''; pl, Jan Heweliusz; – 28 January 1687) was a councillor ...

. Not seeing any nebulae, Messier catalogued this apparent pair instead. The pair were rediscovered by

Friedrich August Theodor Winnecke Friedrich August Theodor Winnecke (February 5, 1835 in Groß-Heere, near Hannover – December 3, 1897 in Bonn) was a German astronomer. Winnecke worked at Pulkovo Observatory near Saint Petersburg from 1858 to 1865, but returned to Germany an ...

in 1863, and included in the

Winnecke Catalogue of Double Stars Winnecke Catalogue of Double Stars is a list of seven "new" double stars published by German Astronomer August Winnecke in Astronomische Nachrichten in 1869. Winnecke later noted that three of the double stars he catalogued had been discovered earl ...

as number 4. Burnham calls M40 "one of the few real mistakes in the

Messier catalog The Messier objects are a set of 110 astronomical objects catalogued by the French astronomer Charles Messier in his ''Catalogue des Nébuleuses et des Amas d'Étoiles'' (''Catalogue of Nebulae and Star Clusters''). Because Messier was only int ...

," faulting Messier for including it when all he saw was a double star, not a nebula of any sort. In 1991 the separation between the components was measured at 51.7 ″, an increase since 1764. Data gathered by astronomers Brian Skiff (2001) and Richard L. Nugent (2002) strongly suggested the subject was merely an optical double star rather than a physically connected (binary) system. The A star that seems the brighter is over twice as far as B. Parallax measurements from the Gaia satellite show the two stars, HD 238107 and HD 238108, are at distances of and respectively.

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*
SEDS: Messier Object 40

* {{Sky, 12, 22, 12.5, , 58, 04, 59, 510 Double stars

Winnecke 4 Winnecke 4 (also known as Messier 40 or WNC 4) is an optical double star consisting of two unrelated stars in a northerly zone of the sky, Ursa Major. The pair were discovered by Charles Messier in 1764 while he was searching for a neb ...

Ursa Major (constellation) 4 Orion–Cygnus Arm 17641024 238107/8 G-type main-sequence stars K-type giants

See also

References

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