53 Eridani

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53 Eridani
Observation data
Epoch J2000      Equinox J2000
Constellation Eridanus
Right ascension  04h 38m 10.82486s[1]
Declination −14° 18′ 14.4600″[1]
Apparent magnitude (V) 3.87[2] (4.02 / 6.95)[3]
Spectral type K1III[4]
U−B color index +1.03[5]
B−V color index +1.09[5]
Radial velocity (Rv)43.33 ± 0.28[6] km/s
Proper motion (μ) RA: -76.59[1] mas/yr
Dec.: -176.78[1] mas/yr
Parallax (π)29.69 ± 0.37[1] mas
Distance110 ± 1 ly
(33.7 ± 0.4 pc)
Period (P)77.4 ± 1.5 yr
Semi-major axis (a)0.7069 ± 0.0093″
Eccentricity (e)0.666 ± 0.017
Inclination (i)59.8 ± 1.8°
Longitude of the node (Ω)171.25 ± 0.96°
Periastron epoch (T)1976.77 ± 0.26
Argument of periastron (ω)
23.5 ± 1.8°
53 Eri A
Mass1.07 ± 0.25[7] M
Radius9.8[7] R
Luminosity37[6] L
Surface gravity (log g)2.49 ± 0.23[7] cgs
Temperature4603[6] K
Metallicity [Fe/H]-0.11[6] dex
Other designations
BD−14° 933, FK5 172, GJ 9160, HD 29503, HIP 21594, HR 1481, SAO 149781, WDS 04382+1418
Database references
53 Eri A
53 Eri B

53 Eridani (abbreviated 53 Eri), also designated l Eridani (l Eri), is a binary star in the constellation of Eridanus. The system has a combined apparent magnitude of 3.87, making it visible to the naked eye even in inner city skies.[8] Parallax estimates made by the Hipparcos spacecraft put it at a distance of about 110 light-years, or 33.7 parsecs from the Sun.[1]

The two components are designated 53 Eridani A (officially named Sceptrum)[9] and B.


53 Eridani is the system's Flamsteed designation; l Eridani its Bayer designation. The designations of the two components as 53 Eridani 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).[10]

53 Eridani bore the traditional name Sceptrum, Latin for "scepter", as it was one of the brighter stars, designated "p Sceptri (Brandenburgici)", in the obsolete constellation of Sceptrum Brandenburgicum. The constellation was coined by Gottfried Kirch to honor the Brandenburg province of Prussia, and although it was later used in other atlases by Johann Elert Bode, the constellation fell out of use.[11][12] In 2016, the IAU organized a Working Group on Star Names (WGSN)[13] to catalog and standardize proper names for stars; the WGSN decided to attribute proper names to individual stars rather than entire multiple systems.[14] It approved the name Sceptrum for the component 53 Eridani A on 30 June 2017 and it is now so included in the List of IAU-approved Star Names.[9]


53 Eridani is a visual binary, where the orbit of the two stars is calculated from their orbital motions. The primary star, 53 Eridani A, is an evolved red giant with a spectral type of K1III,[4] it is almost ten times as wide as the Sun and slightly more massive than the Sun.[7] The secondary star, 53 Eridani B, has an apparent magnitude of 6.95[3] and its spectral type is unknown. The two have an orbital period of 77 years and have a quite eccentric orbit, at 0.666.[3] The total mass of the system is 2.49 M.[15]


  1. ^ a b c d e f van Leeuwen, F.; et al. (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. ^ Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.
  3. ^ a b c d "Sixth Catalog of Orbits of Visual Binary Stars". United States Naval Observatory. Retrieved 15 May 2017.
  4. ^ a b Gray, R. O.; Corbally, C. J.; Garrison, R. F.; McFadden, M. T.; Bubar, E. J.; McGahee, C. E.; O'Donoghue, A. A.; Knox, E. R. (2006). "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 pc--The Southern Sample". The Astronomical Journal. 132: 161. arXiv:astro-ph/0603770. Bibcode:2006AJ....132..161G. doi:10.1086/504637.
  5. ^ a b Johnson, H. L. (1966). "UBVRIJKL Photometry of the Bright Stars". Communications of the Lunar and Planetary Laboratory. 4: 99. Bibcode:1966CoLPL...4...99J.
  6. ^ a b c d Massarotti, Alessandro; Latham, David W.; Stefanik, Robert P.; Fogel, Jeffrey (2008). "Rotational and Radial Velocities for a Sample of 761 Hipparcos Giants and the Role of Binarity". The Astronomical Journal. 135: 209. Bibcode:2008AJ....135..209M. doi:10.1088/0004-6256/135/1/209.
  7. ^ a b c d Allende Prieto, C.; Lambert, D. L. (1999). "Fundamental parameters of nearby stars from the comparison with evolutionary calculations: masses, radii and effective temperatures". Astronomy and Astrophysics. 352: 555–562. arXiv:astro-ph/9911002. Bibcode:1999A&A...352..555A.
  8. ^ Bortle, John E. (February 2001). "The Bortle Dark-Sky Scale". Sky & Telescope. Sky Publishing Corporation. Retrieved 15 May 2017.
  9. ^ a b "Naming Stars". IAU.org. Retrieved 16 December 2017.
  10. ^ 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].
  11. ^ Ian Ridpath. "Sceptrum Brandenburgicum". Star Tales. Retrieved 15 May 2017.
  12. ^ Barentine, John C. (2015). The Lost Constellations: A History of Obsolete, Extinct, or Forgotten Star Lore. New York, New York: Springer. p. 365.
  13. ^ "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
  14. ^ "WG Triennial Report (2015-2018) - Star Names" (PDF). p. 5. Retrieved 2018-07-14.
  15. ^ Söderhjelm, Staffan (1999). "Visual binary orbits and masses POST HIPPARCOS". Astronomy and Astrophysics. 341: 121–140. Bibcode:1999A&A...341..121S.