Phi1 Ceti

Phi1 Ceti is a single[9] star located in the equatorial constellation of 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. 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]

For other stars with this Bayer designation, see φ Ceti.
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]
Characteristics
Spectral type K0 III[3]
U−B color index +0.83[2]
B−V color index +1.00[2]
Variable type suspected[4]
Astrometry
Radial velocity (Rv)+0.33±0.63[5] 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[6]
Details[5]
Mass1.60[7] 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[7] Gyr
Other designations
φ1 Cet, 17 Ceti, NSV 278, BD−11°128, FK5 2048, HD 4188, HIP 3455, HR 194, SAO 147423[8]
Database references
SIMBADdata

At an age of about 2.21[7] billion years, Phi1 Ceti is an evolved red clump[11] 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.[4] It has 1.6[7] times the mass of the Sun and has expanded to 11 times the Sun's radius. The star is radiating 54 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,775 K.[5]

References
  1. 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.
  2. Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99): 99, Bibcode:1966CoLPL...4...99J.
  3. 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. VSX (January 18, 2010), "NSV 278", AAVSO Website, American Association of Variable Star Observers, retrieved 2017-04-25.
  5. 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.
  6. 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.
  7. Luck, R. Earle (2015), "Abundances in the Local Region. I. G and K Giants", Astronomical Journal, 150 (3), 88, arXiv:1507.01466, Bibcode:2015AJ....150...88L, doi:10.1088/0004-6256/150/3/88, S2CID 118505114.
  8. "phi01 Cet". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-04-25.
  9. Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
  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:1005.1205, Bibcode:2010AJ....140..293B, doi:10.1088/0004-6256/140/2/293, S2CID 118455341.
  11. 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:1006.3857, Bibcode:2010MNRAS.408.1225P, doi:10.1111/j.1365-2966.2010.17195.x, S2CID 44228180.
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