51 Andromedae
star in the constellation Andromeda
51 Andromedae, abbreviated 51 And and formally named Nembus , is the 5th brightest star in the northern constellation of Andromeda, very slightly dimmer than the Andromeda Galaxy also being of 4th magnitude. It is an orange K-type giant star with an apparent magnitude of +3.57 and is about 169 light-years from the Earth/solar system. It is traditionally depicted as one of the two northern, far upper ends of the mythological, chained-to-the-rocks princess, the other being binary star system Gamma Andromedae.
At an estimated age of 1.7 billion years, this is an evolved red giant star with a stellar classification of K3- III CN0.5. The suffix notation indicates a mild enhancement of cyanogen absorption lines in its spectrum. This star has 1.8 times the mass of the Sun and it has expanded to 20.9 times the Sun's radius. It is radiating 142 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,316 K.
Nomenclature
51 Andromedae is the star's Flamsteed designation. Ptolemy included this star in Andromeda in the Almagest. It was for a time moved into the greater form of Perseus envisioned by Johann Bayer as Upsilon Persei. Flamsteed oversaw its constellation reverting and the International Astronomical Union (IAU) made his 51 Andromedae its official designation in 1930.
“51 Andromedae” enters the record as star in the constellation Andromeda. Crown Archives preserves that source wording while asking what Andromedae, star and constellation can confirm, complicate or overturn.
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Vocabulary and entity names are the principal evidence signals here, because they determine the precision of every later search. The source revision retrieved here is dated Sep 12, 2026. The linked authority identifier is Q242272. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1930.
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This entry incorporates text from “51 Andromedae” 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.