Phi Centauri

φ Centauri
Location of φ Centauri (circled)
Observation data
Epoch J2000.0      Equinox ICRS
Constellation Centaurus
Right ascension 13h 58m 16.27s
Declination −42° 06′ 02.7″
Apparent magnitude (V) +3.745
Characteristics
Spectral type B2 IV
U−B color index −0.851
B−V color index −0.222
Astrometry
Radial velocity (Rv)+5.3±1.5 km/s
Proper motion (μ) RA: −22.77±0.15 mas/yr
Dec.: −20.13±0.12 mas/yr
Parallax (π)6.21±0.17 mas
Distance530 ± 10 ly
(161 ± 4 pc)
Absolute magnitude (MV)−2.20
Details
Mass8.5±0.3 M☉
Radius4.19±0.35 R☉
Luminosity4,000 L☉
Surface gravity (log g)4.08±0.07 cgs
Temperature21,638±388 K
Rotational velocity (v sin i)79 km/s
Age18.0±3.2 Myr
Other designations
φ Cen, CD−41°8329, GC 18874, HD 121743, HIP 68245, HR 5248, SAO 224577
Database references
SIMBADdata

Phi Centauri is a blue-white hued star in the southern constellation Centaurus. Its name is a Bayer designation that is Latinized from φ Centauri, and abbreviated Phi Cen or φ Cen. This star is visible to the naked eye with an apparent visual magnitude of +3.7. The annual parallax shift is 6.21 mas as measured from Earth, which yields a distance estimate of around 530 light years. It is moving further from the Sun with a radial velocity of +5 km/s.

This is a B-type subgiant star with a stellar classification of B2 IV. It has no known companions, but does show radial velocity variations and higher order pulsations in the spectrum. The star is just 18 million years old with 8.5 times the mass of the Sun and has 4.2 times the Sun's radius. It is radiating around 4,000 times the Sun's luminosity from its photosphere at an effective temperature of about 21,638 K.

This star is a proper motion member of the Upper Centaurus–Lupus sub-group in the Scorpius–Centaurus OB association, the nearest such co-moving association of massive stars to the Sun.

References

  1. 1 2 3 4 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 XHIP record for this object at VizieR.
  2. 1 2 3 4 5 6 7 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. Vizier catalog entry
  3. 1 2 3 4 5 6 Tetzlaff, N.; et al. (January 2011), "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun", Monthly Notices of the Royal Astronomical Society, 410 (1): 190–200, arXiv:1007.4883, Bibcode:2011MNRAS.410..190T, doi:10.1111/j.1365-2966.2010.17434.x, S2CID 118629873.
  4. 1 2 Gutierrez-Moreno, Adelina; Moreno, Hugo (June 1968), "A photometric investigation of the Scorpio-Centaurus association", Astrophysical Journal Supplement, 15: 459, Bibcode:1968ApJS...15..459G, doi:10.1086/190168.
  5. 1 2 Gontcharov, G. A. (November 2006), "Pulkovo Compilation of Radial Velocities for 35495 Hipparcos stars in a common system", Astronomy Letters, 32 (11): 759–771, arXiv:1606.08053, Bibcode:2006AstL...32..759G, doi:10.1134/S1063773706110065, S2CID 119231169.
  6. 1 2 3 4 5 Fitzpatrick, E. L.; Massa, D. (March 2005), "Determining the Physical Properties of the B Stars. II. Calibration of Synthetic Photometry", The Astronomical Journal, 129 (3): 1642–1662, arXiv:astro-ph/0412542, Bibcode:2005AJ....129.1642F, doi:10.1086/427855, S2CID 119512018.
  7. 1 2 3 de Geus, E. J.; et al. (June 1989), "Physical parameters of stars in the Scorpio-Centaurus OB association", Astronomy and Astrophysics, 216 (1–2): 44–61, Bibcode:1989A&A...216...44D.
  8. ↑ Wolff, S. C.; et al. (2007), "Rotational Velocities for B0-B3 Stars in Seven Young Clusters: Further Study of the Relationship between Rotation Speed and Density in Star-Forming Regions", The Astronomical Journal, 133 (3): 1092–1103, arXiv:astro-ph/0702133, Bibcode:2007AJ....133.1092W, doi:10.1086/511002, S2CID 119074863.
  9. ↑ "phi Cen", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 2026-01-03
  10. ↑ Alecian, E.; et al. (July 2014), "Discovery of new magnetic early-B stars within the MiMeS HARPSpol survey", Astronomy & Astrophysics, 567: 19, arXiv:1404.5508, Bibcode:2014A&A...567A..28A, doi:10.1051/0004-6361/201323286, S2CID 119161720, A28.