Pi Ceti

Pi Ceti
	Location of Pi Ceti (circled)
Observation data; Epoch J2000.0 Equinox J2000.0 (ICRS)
Constellation	Cetus
Right ascension	02h 44m 07.34928s
Declination	−13° 51′ 31.3130″
Apparent magnitude (V)	4.238
Characteristics
Spectral type	B7 V or B7 IV
U−B color index	−0.396
B−V color index	−0.130
Astrometry
Proper motion (μ)	RA: −8.62 mas/yr ; Dec.: −9.07 mas/yr
Parallax (π)	8.30 ± 0.21 mas
Distance	393 ± 10 ly ; (120 ± 3 pc)
Absolute magnitude (MV)	−1.16
Orbit
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
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 dex
Rotational velocity (v sin i)	20.9±1.2 km/s
Age	0.3+0.1; −0.1 Myr
Other designations
	π Cet, 89 Ceti, BD−14 519, FK5 97, HD 17081, HIP 12770, HR 811, SAO 148575.
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]

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).^[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]

References

^ ^a ^b ^c ^d ^e ^f van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357, S2CID 18759600.
^ ^a ^b ^c ^d Gutierrez-Moreno, Adelina; et al. (1966), "A System of photometric standards", Publications of the Department of Astronomy University of Chile, 1, Publicaciones Universidad de Chile, Department de Astronomy: 1–17, Bibcode:1966PDAUC...1....1G.
^ ^a ^b Buscombe, W. (1962), "Spectral classification of Southern fundamental stars", Mount Stromlo Observatory Mimeogram, 4: 1, Bibcode:1962MtSOM...4....1B.
^ ^a ^b Hohle, M. M.; et al. (April 2010), "Masses and luminosities of O- and B-type stars and red supergiants", Astronomische Nachrichten, 331 (4): 349, arXiv:1003.2335, Bibcode:2010AN....331..349H, doi:10.1002/asna.200911355, S2CID 111387483.
^ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
^ ^a ^b Lacy, C. H. S.; et al. (March 1997), "The Spectroscopic Orbit of Pi Ceti", Astronomical Journal, 113: 1088, Bibcode:1997AJ....113.1088L, doi:10.1086/118325.
^ ^a ^b ^c Folsom, C. P.; et al. (May 2012), "Chemical abundances of magnetic and non-magnetic Herbig Ae/Be stars", Monthly Notices of the Royal Astronomical Society, 422 (3): 2072–2101, arXiv:1202.1845, Bibcode:2012MNRAS.422.2072F, doi:10.1111/j.1365-2966.2012.20718.x, S2CID 119100447.
^ Prugniel, Ph.; Vauglin, I.; Koleva, M. (July 2011), "The atmospheric parameters and spectral interpolator for the MILES stars", Astronomy & Astrophysics, 531: A165, arXiv:1104.4952, Bibcode:2011A&A...531A.165P, doi:10.1051/0004-6361/201116769, S2CID 54940439.
^ "pi. Cet -- Spectroscopic binary", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2017-02-08.
^ Allen, R. H. (1963). Star Names: Their Lore and Meaning (Reprint ed.). New York: Dover Publications Inc. p. 162. ISBN 0-486-21079-0. Retrieved 2010-12-12.
^ Jack W. Rhoads - Technical Memorandum 33-507-A Reduced Star Catalog Containing 537 Named Stars, Jet Propulsion Laboratory, California Institute of Technology; November 15, 1971
^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 12 日