Tau1 Eridani

Tau1 Eridani, Latinized from τ1 Eridani, is a binary star[6] system 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] At present, the system is moving away from the Sun with a radial velocity of +26 km/s.[4] About 305,000 years ago, it made perihelion passage at an estimated distance of 30.5 ly (9.35 pc).[11]

For other star systems with this Bayer designation, see Tau Eridani.
τ1 Eridani
Observation data
Epoch J2000      Equinox J2000
Constellation Eridanus
Right ascension 02h 45m 06.18710s[1]
Declination −18° 34′ 21.2149″[1]
Apparent magnitude (V) 4.46[2]
Characteristics
Spectral type F7V[3]
U−B color index +0.00[2]
B−V color index +0.48[2]
Astrometry
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
Distance46 ± 1 ly
(14.2 ± 0.4 pc)
Absolute magnitude (MV)+3.68[5]
Orbit[6]
Period (P)958 d
Eccentricity (e)0.45
Periastron epoch (T)39391.9
Argument of periastron (ω)
(secondary)		180°
Details
Mass1.15[7] M☉
Surface gravity (log g)4.34[8] cgs
Temperature6,231[8] K
Metallicity [Fe/H]−0.08 ± 0.06[8] dex
Rotational velocity (v sin i)28.02[9] km/s
Other designations
1 Eri, BD−19° 518, FK5 2075, GJ 111, HD 17206, HIP 12843, HR 818, SAO 11557[10]
Database references
SIMBADdata

Tau1 Eridani was a latter designation of 90 Ceti.[12]

Debris disk

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.[13] 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.[14]

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.[15]

References
  1. 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. 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 (1): 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, arXiv:astro-ph/0509399, Bibcode:2006A&A...446..267R, doi:10.1051/0004-6361:20053911.
  6. 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, arXiv:1204.4206, Bibcode:2012AJ....144....7T, doi:10.1088/0004-6256/144/1/7, 7.
  8. 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
  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" (PDF), Astronomy and Astrophysics, 520: A79, arXiv:1002.4391, Bibcode:2010A&A...520A..79M, doi:10.1051/0004-6361/200913725.
  10. "* tau01 Eri". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2015-04-15.
  11. Bailer-Jones, C. A. L. (March 2015), "Close encounters of the stellar kind", Astronomy & Astrophysics, 575: 13, arXiv:1412.3648, Bibcode:2015A&A...575A..35B, doi:10.1051/0004-6361/201425221, A35.
  12. Wagman, M. (August 1987). "Flamsteed's Missing Stars". Journal for the History of Astronomy. 18 (3): 215. Bibcode:1987JHA....18..209W. doi:10.1177/002182868701800305.
  13. 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.
  14. 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.
  15. Jura, M.; et al. (2004). "Mid‐Infrared Spectra of Dust Debris around Main‐Sequence Stars". The Astrophysical Journal Supplement Series. 154 (1): 453–457. arXiv:astro-ph/0405632. Bibcode:2004ApJS..154..453J. doi:10.1086/422975.
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