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66 Eridani
Observation data
Epoch J2000       Equinox J2000
Constellation Eridanus
Right ascension 05h 06m 45.65314s [1]
Declination −04° 39′ 18.5939″ [1]
Apparent magnitude (V) 5.12 [2]
Characteristics
Spectral type B9V [3]
U−B color index -0.16 [4]
B−V color index -0.06 [4]
Variable type α2 CVn
Astrometry
Radial velocity (Rv)32.28 ± 0.10 [5] km/s
Proper motion (μ) RA: 10.70 [1]  mas/ yr
Dec.: -0.78 [1]  mas/ yr
Parallax (π)10.56 ± 0.34  mas [1]
Distance309 ± 10  ly
(95 ± 3  pc)
Absolute magnitude (MV)0.37 [6]
Orbit [5]
Period (P)5.5226013 ± 0.0000020 d
Eccentricity (e)0.0844 ± 0.0013
Periastron epoch (T)2441356.499 ± 0.017
Argument of periastron (ω)
(secondary)		160.9 ± 1.1°
Semi-amplitude (K1)
(primary)		102.83 ± 0.20 km/s
Semi-amplitude (K2)
(secondary)		100.35 ± 0.19 km/s
Details [5]
66 Eri A
Mass2.629 ± 0.032  M☉
Radius1.948 ± 0.063  R☉
Luminosity51.3 ± 3.3  L☉
Surface gravity (log g)4.28 ± 0.03  cgs
Temperature11077  K
Rotational velocity (v sin i)17.1 ± 0.2 km/s
Age30  Myr
66 Eri B
Mass2.566 ± 0.032  M☉
Radius1.919 ± 0.061  R☉
Luminosity46.9 ± 3.0  L☉
Surface gravity (log g)4.28 ± 0.03  cgs
Temperature10914  K
Rotational velocity (v sin i)16.9 ± 0.2 km/s
Other designations
EN Eri, BD−04° 1044, HD 32964, HIP 23794, HR 1657, SAO 131777 [7]
Database references
SIMBAD data

66 Eridani is a binary star in the constellation of Eridanus. The combined apparent magnitude of the system is 5.12 on average. [2] Parallax measurements by Hipparcos put the system at some 309 light-years (95 parsecs) away. [1]

This is a spectroscopic binary: the two stars cannot be individually resolved, but periodic Doppler shifts in its spectrum mean there must be orbital motion. The two stars orbit each other every 5.5226013 days. [5] Their orbit is fairly eccentric, at 0.0844. [5]

The combined spectrum of 66 Eridani matches that of a B-type main-sequence star, [3] and the two stars have similar masses. [5] The spectrum also shows excess of mercury and manganese, as it is a type of chemically peculiar star called a mercury-manganese star. [5] 66 Eridani is an Alpha2 Canum Venaticorum variable. For this reason, it has been given the designation EN Eridani. [7]

References

  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. S2CID  18759600.
  2. ^ a b 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 Houk, N.; Swift, C. (1999). "Michigan catalogue of two-dimensional spectral types for the HD Stars, Vol. 5". Michigan Spectral Survey. 5: 0. Bibcode: 1999MSS...C05....0H.
  4. ^ a b Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode: 1986EgUBV........0M.
  5. ^ a b c d e f g Makaganiuk, V.; Kochukhov, O.; Piskunov, N.; Jeffers, S. V.; Johns-Krull, C. M.; Keller, C. U.; Rodenhuis, M.; Snik, F.; Stempels, H. C.; Valenti, J. A. (2011). "Chemical spots in the absence of magnetic field in the binary Hg Mn star 66 Eridani". Astronomy & Astrophysics. 529: A160. arXiv: 1102.4661. Bibcode: 2011A&A...529A.160M. doi: 10.1051/0004-6361/201016302. S2CID  118419097.
  6. ^ Hubrig, S.; et al. (June 2001), "Search for low-mass PMS companions around X-ray selected late B stars", Astronomy and Astrophysics, 372: 152–164, arXiv: astro-ph/0103201, Bibcode: 2001A&A...372..152H, doi: 10.1051/0004-6361:20010452, S2CID  17507782.
  7. ^ a b "* 66 Eri". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 13 August 2017.
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