X Sagittarii
variable star in the constellation Sagittarius
X Sagittarii is a variable star and candidate binary star system in the southern constellation of Sagittarius, near the western constellation boundary with Ophiuchus. It has a yellow-white hue and is visible to the naked eye with an apparent visual magnitude that fluctuates around 4.54. The star is located at a distance of approximately 950 light years from the Sun based on parallax, and is drifting closer with a radial velocity of −10 km/s. The star has an absolute magnitude of around −2.85.
On August 4, 1866, Johann Friedrich Julius Schmidt discovered that the star is a variable star. This is an F-type bright giant with a stellar classification of F7II. It is a Classical Cepheid variable that ranges in apparent magnitude from 4.20 down to 4.90 with a period of 7.01283 days. Its variation in brightness is accompanied by a change in spectral classification, from G2 to F5. The amplitude of each pulsation causes the stellar radius to vary by ~9%. Analysis of the spectra suggest there are two shock waves per pulsation period, with complicated patterns appearing in the metallic lines. The star is surrounded by an optically-thin circumstellar envelope at 15–20 stellar radii, which appears as an infrared excess of 13.3%.
“X Sagittarii” enters the record as variable star in the constellation Sagittarius. Crown Archives preserves that source wording while asking what Sagittarii, variable and star 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 14, 2026. The linked authority identifier is Q5177833. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1866.
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This entry incorporates text from “X Sagittarii” 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.