YZ Cassiopeiae
star in the constellation Cassiopeia
YZ Cassiopeiae (21 Cas) is a star system 103.8 parsecs (339 ly) away from Earth, in the constellation Cassiopeia. It comprises three stars: an eclipsing Algol-type binary and a visually fainter star about 3000 AU distant. It is faintly visible to the naked eye under good observing conditions.
The primary star in the YZ Cassiopeiae system is a white subgiant (main sequence) star of spectral type A1Vm and 2.31 solar masses (M☉) with a less massive main sequence dwarf star of type F2V and 1.35 M☉.
In 1924, Joel Stebbins announced his discovery that the star, then known as 21 Cassiopeiae, is an eclipsing binary. It was given its variable star designation, YZ Cassiopeiae, in 1925. The apparent magnitude of the eclipsing binary varies from 5.65 to 6.05 with a period of 4.4672 days. Combined, they appear to have a spectral type of A2IV.
The binary has a dimmer (magnitude 9.7 according to Norton, or 10.5 by SIMBAD) companion of 0.8 M☉ orbiting with a period of about 86 580 years.
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This entry incorporates text from “YZ Cassiopeiae” 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.