Xi Cancri

Xi Cancri (ξ Cancri, abbreviated Xi Cnc, ξ Cnc) is a spectroscopic binary star system in the zodiac constellation of Cancer. It is visible to the naked eye with an apparent visual magnitude of +5.15.[2] Based upon parallax measurements obtained during the Hipparcos mission,[1] it is roughly 370 light-years distant from the Sun.

Xi Cancri
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Cancer
Right ascension  09h 09m 21.53325s[1]
Declination +22° 02′ 43.6053″[1]
Apparent magnitude (V) +5.15[2] (5.70 + 6.20)[3]
Characteristics
Spectral type G9 III Fe-1 CH-0.5[4]
U−B color index +0.75[2]
B−V color index +0.96[2]
Astrometry
Radial velocity (Rv)+7.7±0.3[5] km/s
Proper motion (μ) RA: −1.00[1] mas/yr
Dec.: −0.52[1] mas/yr
Parallax (π)8.74 ± 0.49[1] mas
Distance370 ± 20 ly
(114 ± 6 pc)
Absolute magnitude (MV)−0.12[4]
Orbit[6][7]
Period (P)1700.76 d
Semi-major axis (a)0.0105±0.0017[3]″
Eccentricity (e)0.06
Periastron epoch (T)2428876.86 ± 10.0 JD
Argument of periastron (ω)
(secondary)		301.1°
Semi-amplitude (K1)
(primary)		4.4 km/s
Details
Luminosity118[8] L☉
Temperature5,101[8] K
Other designations
Nahn, ξ Cnc, 77 Cancri, BD+22° 2061, FK5 1239, HD 78515, HIP 44946, HR 3627, SAO 80666[9]
Database references
SIMBADdata

The two components are designated Xi Cancri A (formally named Nahn /ˈnɑːn/)[10] and B.

Nomenclature

ξ Cancri (Latinised to Xi Cancri) is the system's Bayer designation. The designations of the two components as Xi Cancri A' and B derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).[11]

Xi Cancri together with Lambda Leonis (Alterf) were the Persian Nahn, "the Nose", and the Coptic Piautos, "the Eye", both lunar asterisms.[12] Nahn was also the name given to Xi Cancri in a 1971 NASA technical memorandum.[13] In 2016, the IAU organized a Working Group on Star Names (WGSN)[14] to catalog and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems.[15] It approved the name Nahn for the component Xi Cancri A on 1 June 2018 and it is now so included in the List of IAU-approved Star Names.[10]

Properties

At its present distance, the visual magnitude is diminished by an extinction factor of 0.135 due to interstellar dust.[3]

Xi Cancri is a single-lined spectroscopic binary star system with an orbital period of 4.66 years, an eccentricity of 0.06, and a semimajor axis of 0.01 arcseconds. The primary, Xi Cancri A, is a yellow G-type giant with an apparent magnitude of +5.70. Its companion, Xi Cancri B, is of magnitude 6.20.[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. Sturch, C. R.; Helfer, H. L. (November 1972), "UBVRI photometry of north galactic pole K giants. II", Astronomical Journal, 77: 726, Bibcode:1972AJ.....77..726S, doi:10.1086/111344.
  3. Malkov, O. Yu.; et al. (2012), "Dynamical masses of a selected sample of orbital binaries", Astronomy & Astrophysics, 546: A69, Bibcode:2012A&A...546A..69M, doi:10.1051/0004-6361/201219774.
  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.
  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 (2): 727, arXiv:astro-ph/0406573, Bibcode:2004A&A...424..727P, doi:10.1051/0004-6361:20041213.
  7. Jackson, E. S.; et al. (May 1957), "The Orbits of the Spectroscopic Binaries Omicron Tauri, Xi Cancri, and Mu Ursae Majories", Astrophysical Journal, 125: 712, Bibcode:1957ApJ...125..712J, doi:10.1086/146345.
  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. "ksi Cnc". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-06-15.
  10. "Naming Stars". IAU.org. Retrieved 18 June 2018.
  11. Hessman, F. V.; Dhillon, V. S.; Winget, D. E.; Schreiber, M. R.; Horne, K.; Marsh, T. R.; Guenther, E.; Schwope, A.; Heber, U. (2010). "On the naming convention used for multiple star systems and extrasolar planets". arXiv:1012.0707 [astro-ph.SR].
  12. Allen, R. H. (1963), Star Names: Their Lore and Meaning (Reprint ed.), New York, NY: Dover Publications Inc., p. 114, ISBN 0-486-21079-0, retrieved 2010-12-12.
  13. Rhoads, Jack W. (November 15, 1971), Technical Memorandum 33-507-A Reduced Star Catalog Containing 537 Named Stars (PDF), Jet Propulsion Laboratory, California Institute of Technology.
  14. "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
  15. "WG Triennial Report (2015–2018) – Star Names" (PDF). p. 5. Retrieved 2018-07-14.
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