Phi1 Ceti

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Phi1 Ceti
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Cetus
Right ascension 00h 44m 11.40013s[1]
Declination −10° 36′ 34.3816″[1]
Apparent magnitude (V) 4.75[2]
Spectral type K0 III[3]
U−B color index +0.83[2]
B−V color index +1.00[2]
Radial velocity (Rv)+0.33±0.63[4] km/s
Proper motion (μ) RA: −8.96[1] mas/yr
Dec.: −113.82[1] mas/yr
Parallax (π)13.96 ± 0.24[1] mas
Distance234 ± 4 ly
(72 ± 1 pc)
Absolute magnitude (MV)0.732[5]
Mass1.60[6] M
Radius11 R
Luminosity54 L
Surface gravity (log g)2.7 cgs
Temperature4,775±5 K
Metallicity [Fe/H]−0.16 dex
Rotational velocity (v sin i)2.3 km/s
Age2.21[6] Gyr
Other designations
φ1 Cet, 17 Cet, BD−11° 128, FK5 2048, HD 4188, HIP 3455, HR 194, SAO 147423[7]
Database references

Phi1 Ceti is a star located in the equatorial constellation Cetus. It is visible to the naked eye with an apparent visual magnitude of +4.78. Based upon an annual parallax shift of 13.96 mas,[1] it is located about 234 light years from the Sun.

At an age of about 2.21[6] billion years, this is an evolved red clump[8] giant star with a stellar classification of K0 III.[3] It is presently on the horizontal branch and is generating energy through the nuclear fusion of helium at its core. The star is suspected of variability; it has been measured to vary between magnitudes 4.75 and 4.78.[9]

Based upon the motion of this star through space, Phi1 Ceti is a probable member of the proposed Wolf 630 moving group. This is a set of stars centered on Wolf 630 that are moving nearly in parallel and have an age of around 2.7±0.5 billion years. They may be former members of a dissolved open cluster.[10]


  1. ^ a b c d e f van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752Freely accessible, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99), Bibcode:1966CoLPL...4...99J. 
  3. ^ a b Houk, N.; Swift, C. (1999), "Michigan catalogue of two-dimensional spectral types for the HD Stars", Michigan Spectral Survey, Ann Arbor, Michigan: Department of Astronomy, University of Michigan, 5, Bibcode:1999MSS...C05....0H. 
  4. ^ a b Massarotti, Alessandro; et al. (January 2008), "Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity", The Astronomical Journal, 135 (1): 209–231, Bibcode:2008AJ....135..209M, doi:10.1088/0004-6256/135/1/209. 
  5. ^ Liu, Y. J.; et al. (2007), "The abundances of nearby red clump giants", Monthly Notices of the Royal Astronomical Society, 382 (2): 553–66, Bibcode:2007MNRAS.382..553L, doi:10.1111/j.1365-2966.2007.11852.x. 
  6. ^ a b c Luck, R. Earle (2015), "Abundances in the Local Region. I. G and K Giants", Astronomical Journal, 150 (3), 88, arXiv:1507.01466Freely accessible, Bibcode:2015AJ....150...88L, doi:10.1088/0004-6256/150/3/88. 
  7. ^ "phi01 Cet". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-04-25. 
  8. ^ Puzeras, E.; et al. (October 2010), "High-resolution spectroscopic study of red clump stars in the Galaxy: iron-group elements", Monthly Notices of the Royal Astronomical Society, 408 (2): 1225–1232, arXiv:1006.3857Freely accessible, Bibcode:2010MNRAS.408.1225P, doi:10.1111/j.1365-2966.2010.17195.x. 
  9. ^ VSX (January 18, 2010), "NSV 278", AAVSO Website, American Association of Variable Star Observers, retrieved 2017-04-25. 
  10. ^ Bubar, Eric J.; King, Jeremy R. (August 2010), "Spectroscopic Abundances and Membership in the Wolf 630 Moving Group", The Astronomical Journal, 140 (2): 293–318, arXiv:1005.1205Freely accessible, Bibcode:2010AJ....140..293B, doi:10.1088/0004-6256/140/2/293.