66 Eridani

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66 Eridani
Eridanus constellation map.svg
Red circle.svg
Location of 66 Eridani (circled)
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? [5]
Astrometry
Radial velocity (Rv)32.28±0.10 [6] 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]
Distance 309 ± 10  ly
(95 ± 3  pc)
Absolute magnitude  (MV)0.37 [7]
Orbit [6]
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 [6]
66 Eri A
Mass 2.629±0.032  M
Radius 1.948±0.063  R
Luminosity 51.3±3.3  L
Surface gravity (log g)4.28±0.03  cgs
Temperature 11,077  K
Rotational velocity (v sin i)17.1±0.2 km/s
Age 30  Myr
66 Eri B
Mass 2.566±0.032  M
Radius 1.919±0.061  R
Luminosity46.9±3.0  L
Surface gravity (log g)4.28±0.03  cgs
Temperature 10,914  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 [8]
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] It lies half a degree northwest of beta Eridani. [8]

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 5.5 days. [6] Their orbit is fairly circular, with an eccentricity of 0.0844. [6]

The combined spectrum of 66 Eridani matches that of a B-type main-sequence star, [3] and the two stars have similar masses. [6] The spectrum also shows excess of mercury and manganese, as it is a type of chemically peculiar star called a mercury-manganese star. [6] 66 Eridani is an Alpha2 Canum Venaticorum variable. For this reason, it has been given the designation EN Eridani.

References

  1. 1 2 3 4 5 6 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. 1 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. 1 2 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. 1 2 Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
  5. Samus', N. N.; Kazarovets, E. V.; Durlevich, O. V.; Kireeva, N. N.; Pastukhova, E. N. (2017). "General catalogue of variable stars: Version GCVS 5.1". Astronomy Reports. 61 (1): 80. Bibcode:2017ARep...61...80S. doi:10.1134/S1063772917010085.
  6. 1 2 3 4 5 6 7 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.
  7. 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.
  8. 1 2 "* 66 Eri". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 13 August 2017.