Zeta Lupi

ζ Lupi (Latinised as Zeta Lupi) is a wide double star in the constellation Lupus, consisting of an orange-hued primary and a fainter secondary with a golden-yellow hue.[11] It is visible to the naked eye with a combined apparent visual magnitude of 3.41.[2] Based upon an annual parallax shift of 27.80[1] mas as seen from Earth, it is located 117.3 light years from the Sun.

ζ Lupi
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Lupus
Right ascension  15h 12m 17.09595s[1]
Declination −52° 05′ 57.2919″[1]
Apparent magnitude (V) 3.41[2] (3.50 + 6.74)[3]
Characteristics
Spectral type G7 III[4]
U−B color index +0.66[2]
B−V color index +0.92[2]
Astrometry
Radial velocity (Rv)−10.0±0.6[5] km/s
Proper motion (μ) RA: −112.92[1] mas/yr
Dec.: −71.18[1] mas/yr
Parallax (π)27.80 ± 0.15[1] mas
Distance117.3 ± 0.6 ly
(36.0 ± 0.2 pc)
Absolute magnitude (MV)0.65[6]
Details
ζ Lup A
Mass2.29[6] M☉
Radius10[7] R☉
Luminosity53[8] L☉
Surface gravity (log g)3.01[9] cgs
Temperature5,335[8] K
Metallicity [Fe/H]0.00±0.02[9] dex
Other designations
ζ Lup, CD−51° 8830, FK5 558, GJ 9512 A, HD 134505, HIP 74395, HR 5649, SAO 242304, WDS J15123-5206A.[10]
Database references
SIMBADdata

This is a probable binary star system.[12] As of 2013, the pair had an angular separation of 71.20 arc seconds along a position angle of 68.8°.[3] The primary, component A, is an evolved G-type giant star with a visual magnitude of 3.50[3] and a stellar classification of G7 III.[4] This is a red clump star, indicating that it is generating energy through the thermonuclear fusion of helium in its core region.[13] Its measured angular diameter is 2.55±0.13 mas,[14] which, at the estimated distance of Zeta Lupi, yields a physical size of about 10 times the radius of the Sun.[7]

The secondary, component B, has a visual magnitude of 6.74.[3]

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. 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. Mason, B. D.; et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal, 122: 3466–3471, Bibcode:2001AJ....122.3466M, doi:10.1086/323920, retrieved 2015-07-22
  4. Gray, R. O.; et al. (July 2006), "Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample", The Astronomical Journal, 132 (1): 161–170, arXiv:astro-ph/0603770, Bibcode:2006AJ....132..161G, doi:10.1086/504637.
  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. Pizzolato, N.; et al. (September 2000), "Evolution of X-ray activity of 1-3 Msun late-type stars in early post-main-sequence phases", Astronomy and Astrophysics, 361: 614–628, Bibcode:2000A&A...361..614P.
  7. Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, 1 (3rd ed.), Birkhäuser, ISBN 3-540-29692-1. The radius (R*) is given by:
  8. McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, arXiv:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x.
  9. Soubiran, Caroline; et al. (June 2016), "The PASTEL catalogue: 2016 version", Astronomy & Astrophysics, 591: 7, arXiv:1605.07384, Bibcode:2016A&A...591A.118S, doi:10.1051/0004-6361/201628497, A118.
  10. "zet Lup". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-03-03.
  11. Streicher, M. (June 2007), "Lupus: a wild animal", Monthly Notes of the Astronomical Society of South Africa, 66 (5 and 6): 124–127, Bibcode:2007MNSSA..66..124S.
  12. 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.
  13. Laney, C. D.; et al. (2012). "A new Large Magellanic Cloud K-band distance from precision measurements of nearby red clump stars". Monthly Notices of the Royal Astronomical Society. 419 (2): 1637. arXiv:1109.4800. Bibcode:2012MNRAS.419.1637L. doi:10.1111/j.1365-2966.2011.19826.x.
  14. Richichi, A.; et al. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics, 431: 773–777, Bibcode:2005A&A...431..773R, doi:10.1051/0004-6361:20042039.
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