Xi<sup>1</sup> Ceti is a binary star system located in the equatorial constellation of Cetus. Its name is a Bayer designation that is Latinized from þ<sup>1</sup> Ceti, and is abbreviated Xi<sup>1</sup> Cet or þ<sup>1</sup> Cet. This system is visible to the naked eye with a combined apparent visual magnitude of +4.36. The distance to this system is approximately 310 light years based on parallax measurements, and it is drifting closer to the Sun with a radial velocity of âÂÂ4 km/s. The proximity of the star to the ecliptic means it is subject to lunar occultations.
The spectroscopic binary nature of Xi<sup>1</sup> Ceti was discovered in 1901 by William Wallace Campbell using the Mills spectrograph at the Lick Observatory. The pair have a circular orbit with a period of 4.5 years and a separation of . It is a suspected eclipsing binary with an amplitude of 0.03 in magnitude, which would suggest the orbital plane has a high inclination.
The primary, designated component A, is a mild barium giant star with a stellar classification of . Morgan and Keenan in 1973 had classified it as a bright giant star with an anomalous underabundance of the CN molecule. Evidence has been found for an overabundance of s-process elements, although this is disputed. The star has 3.4 times the mass and 16.8 times the radius of the Sun. The companion, component B, is a small white dwarf companion with 80% of the mass of the Sun and a class of DA4. It was detected in 1985 by its ultraviolet emission.
In Chinese, (), meaning Circular Celestial Granary, refers to an asterism consisting of ñ Ceti, ú<sup>1</sup> Ceti, û Ceti, ü Ceti, þ<sup>1</sup> Ceti, þ<sup>2</sup> Ceti, ý Ceti, ó Ceti, ô Ceti, 75 Ceti, 70 Ceti, 63 Ceti and 66 Ceti. Consequently, the Chinese name for Xi<sup>1</sup> Ceti itself is "the Fifth Star of Circular Celestial Granary", .