Tau1 Eridani

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HR 818
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)
Period (P) 958 d
Eccentricity (e) 0.45
Periastron epoch (T) 39391.9
Argument of periastron (ω)
Mass 1.15[6] M
Surface gravity (log g) 4.34[7] cgs
Temperature 6,231[7] K
Metallicity [Fe/H] −0.08 ± 0.06[7] dex
Rotational velocity (v sin i) 28.02[8] km/s
Database references
Other designations
BD−19 518, GJ 111, HD 17206, HIP 12843, HR 818, SAO 11557.[9]

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.[5] It is located about 46 light years from the Earth.[1]

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.[10] 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.[11]

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.[12]


  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, arXiv:0708.1752, Bibcode:2007A&A...474..653V, 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 ^ a b c Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV data (SIMBAD), Bibcode:1986EgUBV........0M. 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. 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. ^ 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. 
  6. ^ Tokovinin, Andrei et al. (July 2012), "Revealing Companions to Nearby Stars with Astrometric Acceleration", The Astronomical Journal 144 (1): 10, arXiv:1204.4206, Bibcode:2012AJ....144....7T, doi:10.1088/0004-6256/144/1/7, 7. 
  7. ^ 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, arXiv:astro-ph/0403108, Bibcode:2004A&A...420..183A, doi:10.1051/0004-6361:20035801.  Vizier catalog entry
  8. ^ 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, arXiv:1002.4391, Bibcode:2010A&A...520A..79M, doi:10.1051/0004-6361/200913725. 
  9. ^ "tau01 Eri -- Spectroscopic binary", SIMBAD Astronomical Database (Centre de Données astronomiques de Strasbourg), retrieved 2015-04-15. 
  10. ^ 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. 
  11. ^ Weintraub, D. A. et al. (1994). "A reinterpretation of millimeter observations of nearby IRAS excess stars". The Astronomical Journal 108: 701. doi:10.1086/117107. 
  12. ^ Jura, M. et al. (2004). "Mid‐Infrared Spectra of Dust Debris around Main‐Sequence Stars". The Astrophysical Journal Supplement Series 154: 453. doi:10.1086/422975.