Astronomy:Pi Ceti
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| Observation data 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[1] mas |
| 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]
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
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, doi:10.1051/0004-6361:20078357, Bibcode: 2007A&A...474..653V.
- ↑ 2.0 2.1 2.2 2.3 Gutierrez-Moreno, Adelina et al. (1966), "A System of photometric standards", Publications of the Department of Astronomy University of Chile (Publicaciones Universidad de Chile, Department de Astronomy) 1: 1–17, Bibcode: 1966PDAUC...1....1G.
- ↑ 3.0 3.1 Buscombe, W. (1962), "Spectral classification of Southern fundamental stars", Mount Stromlo Observatory Mimeogram 4: 1, Bibcode: 1962MtSOM...4....1B.
- ↑ 4.0 4.1 Hohle, M. M. et al. (April 2010), "Masses and luminosities of O- and B-type stars and red supergiants", Astronomische Nachrichten 331 (4): 349, doi:10.1002/asna.200911355, Bibcode: 2010AN....331..349H.
- ↑ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A.
- ↑ 6.0 6.1 Lacy, C. H. S. et al. (March 1997), "The Spectroscopic Orbit of Pi Ceti", Astronomical Journal 113: 1088, doi:10.1086/118325, Bibcode: 1997AJ....113.1088L.
- ↑ 7.0 7.1 7.2 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, doi:10.1111/j.1365-2966.2012.20718.x, Bibcode: 2012MNRAS.422.2072F.
- ↑ Prugniel, Ph.; Vauglin, I.; Koleva, M. (July 2011), "The atmospheric parameters and spectral interpolator for the MILES stars", Astronomy & Astrophysics 531: A165, doi:10.1051/0004-6361/201116769, Bibcode: 2011A&A...531A.165P.
- ↑ "pi. Cet -- Spectroscopic binary", SIMBAD Astronomical Database (Centre de Données astronomiques de Strasbourg), http://simbad.u-strasbg.fr/simbad/sim-id?Ident=pi.+Cet, 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. https://archive.org/details/starnamestheirlo00alle/page/162. 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
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