Pi Ceti

Pi Ceti a binary star system in the equatorial constellation of Cetus. Its name is a Bayer designation that is Latinized from π Ceti, and abbreviated Pi Cet or π Cet. The system is located near the eastern boundary of the constellation and is sometimes portrayed as forming part of the Eridanus constellation's asterism. It is visible to the naked eye as a point of light with an apparent visual magnitude of 4.238. Observed to have a half yearly parallax shift of as seen from Earth, it is located at a distance of approximately 393 light years from the Sun. The system is drifting further away from the Sun with a line of sight velocity component of +15 km/s.

This is a single-lined spectroscopic binary system with a nearly circular orbit and a period of 7.45 years. The fact that the system has a negligible eccentricity is surprising for such a long period, and may suggest that the secondary is a white dwarf that had its orbit circularized during a mass-transfer event.

The primary, component A, is a normal B-type star that has been given stellar classifications of B7 V and B7 IV. It appears very young – less than half a million years in age – and may still be on a pre-main sequence track. The star shows no magnetic field but it does emit an infrared excess.

Name

This star, along with ε Cet, ρ Cet and σ Cet, was Al Sufi's Al Sadr al Ḳaiṭos, the Whale's breast/chest (upper torso). Per Jack Rhoads's Reduced Star Catalog Containing 537 Named Stars, Al Sufi's numerically ordered stars (1 to 4), were ρ (rho), σ (sigma), ε (epsilon) and this star.

In Chinese, (), meaning Celestial Meadows, refers to an asterism consisting of π Ceti, and 15 stars in Eridanus: γ, π, δ, ε, ζ, η, and the string of τ (Tau)¹, ², ³, ⁴, ⁵, ⁶, ⁷, ⁸ and ⁹. Consequently, the Chinese name for the star is () meaning Celestial Meadows: seven.

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