45 Cancri
star in the constellation Cancer
45 Cancri is a binary star system in the zodiac constellation of Cancer, located 680 light-years away from the Sun. It has the Bayer designation A1 Cancri; 45 Cancri is the Flamsteed designation. It is visible to the naked eye as a faint, white-hued star at an apparent visual magnitude of 5.62. The pair form a double-lined spectroscopic binary with an orbital period of 2.76 years and an eccentricity of 0.46. They are drifting closer to the Earth with a heliocentric radial velocity of −6 km/s.
The primary, designated component A, is an aging giant star with a stellar classification of G8 III, but has most likely not yet made multiple ascents up the red giant branch. It has 3.11 times the mass of the Sun and has expanded to 14 times the Sun's radius. The star is radiating 210 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 5,058 K. The less evolved secondary, component B is likewise a giant star, having a class of A3 III. It has three times the mass of the Sun and shines with 191 times the Sun's luminosity.
“45 Cancri” enters the record as star in the constellation Cancer. Crown Archives preserves that source wording while asking what Cancri, star and constellation can confirm, complicate or overturn.
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The citation trail is more important than the brevity of the summary: it shows where individual claims can be examined in context. The source revision retrieved here is dated Sep 14, 2026. The linked authority identifier is Q2403477. None of the 0 selected statements returned an explicit reference.
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This entry incorporates text from “45 Cancri” 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.