Observation data Epoch J2000.0 Equinox J2000.0 ( ICRS) | |
---|---|
Constellation | Cetus |
Right ascension | 02h 44m 07.34928s [1] |
Declination | −13° 51′ 31.3130″ [1] |
Apparent magnitude (V) | 4.238 [2] |
Characteristics | |
Spectral type | B7 V [3] or B7 IV [4] |
U−B color index | −0.396 [2] |
B−V color index | −0.130 [2] |
Astrometry | |
Proper motion (μ) |
RA: −8.62
[1]
mas/
yr Dec.: −9.07 [1] mas/ yr |
Parallax (π) | 8.30 ± 0.21 mas [1] |
Distance | 393 ± 10
ly (120 ± 3 pc) |
Absolute magnitude (MV) | −1.16 [5] |
Orbit [6] | |
Period (P) | 2,722±14 d |
Eccentricity (e) | 0.0±0.7 |
Periastron epoch (T) | 2444852 ± 29 JD |
Argument of periastron (ω) (secondary) | 0.0° |
Semi-amplitude (K1) (primary) | 4.33±0.25 km/s |
Details [7] | |
π Cet A | |
Mass | 4.4±0.2 M☉ |
Radius | 4.3±0.3 R☉ |
Luminosity | 468 L☉ |
Surface gravity (log g) | 3.8±0.2 cgs |
Temperature | 12,900±400 K |
Metallicity [Fe/H] | 0.28±0.16 [8] dex |
Rotational velocity (v sin i) | 20.9±1.2 km/s |
Age | 0.3+0.1 −0.1 Myr |
Other designations | |
Database references | |
SIMBAD | data |
Pi Ceti, Latinized from π Ceti, is the Bayer designation for a star system in the equatorial constellation of Cetus. It is visible to the naked eye with an apparent visual magnitude of 4.238. [2] Observed to have an Earth half yearly parallax shift of 8.30 mas, [1] it is around 393 light years from the Sun.
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. [6]
The primary, component A, is a normal B-type star [7] that has been given stellar classifications of B7 V [3] and B7 IV. [4] 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. [7]
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). [10] 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. [11]
In Chinese, 天苑 (Tiān Yuàn), 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 天苑七 (Tiān Yuàn qī) meaning Celestial Meadows: seven. [12]