Iota Pegasi
star in the constellation Pegasus
Iota Pegasi, also named Jiu, is a double-lined spectroscopic binary star system located within the northern constellation of Pegasus, along a line between Lambda and Kappa Pegasi. It is visible to the naked eye as a yellow-hued point of light with a combined apparent visual magnitude of 3.77. The system is located 38.5 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −5.5 km/s.
Nomenclature
ι Pegasi, Latinized as Iota Pegasi, is the star's Bayer designation. In Chinese astronomy, this star is part of the constellation Jiù (Mortar, 臼). The IAU Working Group on Star Names adopted the name Jiu for this star on 13 August 2026, after this Chinese constellation.
Properties
The binary nature of this system was discovered by W. W. Campbell in 1899 and the initial orbital elements were estimated by H. D. Curtis in 1904. The primary, designated component Aa, is a yellowish-white star somewhat brighter than the sun. It and the dimmer component Ab orbit each other with a period of about 10 days and a small, but non-zero eccentricity. They appear to be very young stars, close to zero-age main sequence.
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This entry incorporates text from “Iota Pegasi” 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.