Tau1 Eridani

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τ1 Eridani
Observation data
Epoch 2000      Equinox 2000
Constellation Eridanus
Right ascension 02h 45m 06.18710s[1]
Declination −18° 34′ 21.2149″[1]
Apparent magnitude (V) 4.46[2]
Spectral type F7V[3]
U−B color index +0.00[2]
B−V color index +0.48[2]
Radial velocity (Rv) +25.9[4] km/s
Proper motion (μ) RA: +334.20[1] mas/yr
Dec.: +37.19[1] mas/yr
Parallax (π) 70.32 ± 1.83[1] mas
Distance 46 ± 1 ly
(14.2 ± 0.4 pc)
Absolute magnitude (MV) +3.68[5]
Period (P) 958 d
Eccentricity (e) 0.45
Periastron epoch (T) 39391.9
Argument of periastron (ω)
Mass 1.15[7] M
Surface gravity (log g) 4.34[8] cgs
Temperature 6,231[8] K
Metallicity [Fe/H] −0.08 ± 0.06[8] dex
Rotational velocity (v sin i) 28.02[9] km/s
Other designations
1 Eridani, BD−19° 518, Gl 111, HD 17206, HIP 12843, HR 818, SAO 11557.[10]
Database references

Tau1 Eridani (τ1 Eri) is a binary star in the constellation Eridanus. It has an apparent magnitude of 4.46, making it visible to the naked eye in suitably dark conditions. This a spectroscopic binary with an orbital period of 958 days.[6] It is located about 46 light years from the Earth.[1]

Tau1 Eridani was a latter designation of 90 Ceti.[11]

Debris disk[edit]

A moderate far-infrared excess was observed for this star system, in the 12μm, 25μm, 60μm and 100μm wavelengths, by the Infrared Astronomical Satellite (IRAS), and published in 1993.[12] This discovery was subsequently interpreted as indicating a debris disk with a radius near to 500 AU. It was further speculated that, if the star system had been observed at longer wavelengths, it was likely the debris disk would have been seen to have a radius considerably wider than 500 AU.[13]

Later observations made by the Spitzer Space Telescope, published in 2004, detected no substantial infrared excess around the stars, within the 14-35μm range of wavelengths.[14]


  1. ^ a b c d e f van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, Bibcode:2007A&A...474..653V, arXiv:0708.1752Freely accessible, doi:10.1051/0004-6361:20078357. 
  2. ^ a b c Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV data, SIMBAD, Bibcode:1986EgUBV........0M. 
  3. ^ Abt, H. A. (2009). "MK Classifications of Spectroscopic Binaries". The Astrophysical Journal Supplement Series. 180: 117–118. Bibcode:2009ApJS..180..117A. doi:10.1088/0067-0049/180/1/117. 
  4. ^ Nordström, B.; et al. (2004), "The Geneva-Copenhagen survey of the Solar neighbourhood. Ages, metallicities, and kinematic properties of ~14000 F and G dwarfs", Publications of the Astronomical Society of Australia, 21 (2): 129–133, Bibcode:2004PASA...21..129N, doi:10.1071/AS04013. 
  5. ^ Reiners, A. (January 2006), "Rotation- and temperature-dependence of stellar latitudinal differential rotation", Astronomy and Astrophysics, 446 (1): 267–277, Bibcode:2006A&A...446..267R, arXiv:astro-ph/0509399Freely accessible, doi:10.1051/0004-6361:20053911. 
  6. ^ a b Batten, A. H.; et al. (1978), "Seventh catalogue of the orbital elements of spectroscopic binary systems", Publications of the Dominion Astrophysical Observatory Victoria, 15: 121–295;150–151, Bibcode:1978PDAO...15..121B. 
  7. ^ Tokovinin, Andrei; et al. (July 2012), "Revealing Companions to Nearby Stars with Astrometric Acceleration", The Astronomical Journal, 144 (1): 10, Bibcode:2012AJ....144....7T, arXiv:1204.4206Freely accessible, doi:10.1088/0004-6256/144/1/7, 7. 
  8. ^ a b c Allende Prieto, C.; et al. (June 2004), "S4N: A spectroscopic survey of stars in the solar neighborhood. The Nearest 15 pc", Astronomy and Astrophysics, 420: 183–205, Bibcode:2004A&A...420..183A, arXiv:astro-ph/0403108Freely accessible, doi:10.1051/0004-6361:20035801.  Vizier catalog entry
  9. ^ Martínez-Arnáiz, R.; et al. (September 2010), "Chromospheric activity and rotation of FGK stars in the solar vicinity. An estimation of the radial velocity jitter", Astronomy and Astrophysics, 520: A79, Bibcode:2010A&A...520A..79M, arXiv:1002.4391Freely accessible, doi:10.1051/0004-6361/200913725. 
  10. ^ "tau01 Eri -- Spectroscopic binary", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2015-04-15. 
  11. ^ Wagman, M. (August 1987). "Flamsteed's Missing Stars". Journal for the History of Astronomy, Vol.18, NO. 3/AUG, P.209, 1987. 18: 215. Bibcode:1987JHA....18..209W. doi:10.1177/002182868701800305. 
  12. ^ Backman, Dana E; et al. (1993), "Main-sequence stars with circumstellar solid material - The VEGA phenomenon", Protostars and planets III (A93-42937 17-90): 1253–1304, Bibcode:1993prpl.conf.1253B. 
  13. ^ Weintraub, D. A.; et al. (1994). "A reinterpretation of millimeter observations of nearby IRAS excess stars". The Astronomical Journal. 108: 701. Bibcode:1994AJ....108..701W. doi:10.1086/117107. 
  14. ^ Jura, M.; et al. (2004). "Mid‐Infrared Spectra of Dust Debris around Main‐Sequence Stars". The Astrophysical Journal Supplement Series. 154: 453–457. Bibcode:2004ApJS..154..453J. arXiv:astro-ph/0405632Freely accessible. doi:10.1086/422975.