Upsilon2 Centauri

Upsilon2 Centauri (υ2 Centauri) is a binary star[6] system in the southern constellation Centaurus. It is visible to the naked eye with an apparent visual magnitude of +4.33.[2] Based upon an annual parallax shift of just 2.57 mas as seen from Earth,[1] this star is located roughly 1,300 light years from the Sun. Relative to its neighbors, the system has a peculiar velocity of 39.2+8.8
−15.2 km/s and it may form a runaway star system.[9]

For other stars with this Bayer designation, see υ Centauri.
Upsilon2 Centauri
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Centaurus
Right ascension  14h 01m 43.49909 s[1]
Declination −45° 36′ 12.2767″[1]
Apparent magnitude (V) +4.33[2]
Characteristics
Spectral type F7 II/III[3]
U−B color index +0.26[2]
B−V color index +0.61[2]
Variable type None[4]
Astrometry
Radial velocity (Rv)−7.8±7.4[5] km/s
Proper motion (μ) RA: +8.64±1.09[1] mas/yr
Dec.: −16.25±0.88[1] mas/yr
Parallax (π)2.57 ± 1.05[1] mas
Distanceapprox. 1,300 ly
(approx. 400 pc)
Absolute magnitude (MV)−3.51[4]
Orbit[6]
Period (P)207.357 d
Eccentricity (e)0.55
Periastron epoch (T)2423880.5 JD
Argument of periastron (ω)
(secondary)		88°
Semi-amplitude (K1)
(primary)		12.7 km/s
Details
Mass6.86±0.39[7] M☉
Luminosity (bolometric)3,919[7] L☉
Surface gravity (log g)2.00[8] cgs
Temperature6,495[7] K
Rotational velocity (v sin i)0.0[8] km/s
Age45.9±4.0[9] Myr
Other designations
υ2 Cen, CD−44° 9040, GC 18939, HD 122223, HIP 68523, HR 5260, SAO 224621[10]
Database references
SIMBADdata

This is a single-lined spectroscopic binary star system with an orbital period of 207.357 days and an eccentricity of 0.55.[6] The primary component has the spectrum of an evolved F-type giant/bright giant hybrid with a stellar classification of F7 II/III.[3] It is around 46[9] million years old with 6.9 times the mass of the Sun. The star is radiating 3,919 times the Sun's luminosity from its photosphere at an effective temperature of 6,495 K.[7]

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.
  2. Fernie, J. D. (1983), "New UBVRI photometry for 900 supergiants", Astrophysical Journal Supplement Series, 52: 7, Bibcode:1983ApJS...52....7F, doi:10.1086/190856.
  3. Houk, N. (1987), "Michigan Catalogue of two dimensional spectral types for the HD stars", Michigan Spectral Survey, 2, Bibcode:1978mcts.book.....H.
  4. Eggen, O. J. (July 1985), "Cepheids and nonvariable supergiants", Astronomical Journal, 90: 1260–1277, Bibcode:1985AJ.....90.1260E, doi:10.1086/113834.
  5. de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, A61.
  6. Pourbaix, D.; et al. (2004), "SB9: The Ninth Catalogue of Spectroscopic Binary Orbits", Astronomy & Astrophysics, 424: 727–732, arXiv:astro-ph/0406573, Bibcode:2004A&A...424..727P, doi:10.1051/0004-6361:20041213.
  7. 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.
  8. Mallik, Sushma V.; et al. (October 2003), "Lithium and rotation in F and G dwarfs and subgiants", Astronomy and Astrophysics, 409: 251–261, Bibcode:2003A&A...409..251M, doi:10.1051/0004-6361:20031084.
  9. Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (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.
  10. "ups02 Cen". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-08-29.
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