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τ⁸ Eridani
	; A light curve for Tau8 Eridani, plotted from TESS data
Observation data; Epoch J2000.0 Equinox J2000.0 (ICRS)
Constellation	Eridanus
Right ascension	03h 53m 42.70302s
Declination	−24° 36′ 44.0309″
Apparent magnitude (V)	4.63 - 4.65
Characteristics
Spectral type	B6 V
U−B color index	−0.48
B−V color index	−0.13
Variable type	SPB
Astrometry
Radial velocity (Rv)	+23 km/s
Proper motion (μ)	RA: +31.28 mas/yr ; Dec.: −7.49 mas/yr
Parallax (π)	8.65 ± 0.30 mas
Distance	380 ± 10 ly ; (116 ± 4 pc)
Absolute magnitude (MV)	−0.67
Orbit
Period (P)	459±4 d
Eccentricity (e)	0.18±0.02
Periastron epoch (T)	2450954±7 JD
Argument of periastron (ω); (secondary)	106±5°
Semi-amplitude (K1); (primary)	21.7±0.4 km/s
Details
τ8 Eri A
Mass	5.0±0.1 M☉
Luminosity	256 L☉
Surface gravity (log g)	4.00 cgs
Temperature	11,858 K
Rotational velocity (v sin i)	30 km/s
Age	32.8±9.9 Myr
Other designations
	τ8 Eridani, τ8 Eri, 33 Eridani, CD−24°1945, HD 24587, HIP 18216, HR 1213, SAO 168925.
Database references
SIMBAD	data

Tau⁸ Eridani, Latinized from τ⁸ Eridani, is a binary star system in the constellation Eridanus. It is visible to the naked eye with a combined apparent visual magnitude of 4.65.^[5] The distance to this system can be estimated via the parallax method, yielding a value of around 380 light years.^[2]

This is a single-lined^[13] spectroscopic binary star system with an orbital period of about 459 days and an eccentricity of 0.18.^[8] The primary component is a B-type main sequence star with a stellar classification of B6 V.^[4] Gautier Mathys et al. announced that the star is variable, in 1986.^[14] It is a slowly pulsating B-type star that undergoes radial-velocity variation with a frequency of 1.1569 times per day.^[13] The star has about five^[9] times the mass of the Sun and shines with 256 times the Sun's luminosity.^[10] The outer atmosphere has an effective temperature of 11,858^[10] K and may possess a longitudinal magnetic field with a strength of −140±71 G.^[15]

References

^ MAST: Barbara A. Mikulski Archive for Space Telescopes, Space Telescope Science Institute, retrieved 24 September 2022.
^ ^a ^b ^c ^d ^e ^f van Leeuwen, F. (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.
^ ^a ^b "Tau 8 Eri", The International Variable Star Index, AAVSO – American Association of Variable Star Observers, retrieved 16 February 2018.
^ ^a ^b ^c Abt, Helmut A.; et al. (July 2002), "Rotational Velocities of B Stars", The Astrophysical Journal, 573 (1): 359–365, Bibcode:2002ApJ...573..359A, doi:10.1086/340590.
^ ^a ^b ^c Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99): 99, Bibcode:1966CoLPL...4...99J.
^ Evans, D. S. (June 20–24, 1966), Batten, Alan Henry; Heard, John Frederick (eds.), "The Revision of the General Catalogue of Radial Velocities", Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30, vol. 30, University of Toronto: International Astronomical Union, p. 57, Bibcode:1967IAUS...30...57E.
^ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
^ ^a ^b De Cat, P.; Aerts, C.; De Ridder, J.; Kolenberg, K.; Meeus, G.; Decin, L. (2000), "A study of bright southern slowly pulsating B stars. I. Determination of the orbital parameters and of the main frequency of the spectroscopic binaries", Astronomy and Astrophysics, 355: 1015, Bibcode:2000A&A...355.1015D.
^ ^a ^b ^c Tetzlaff, N.; et al. (January 2011), "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun", Monthly Notices of the Royal Astronomical Society, 410 (1): 190–200, arXiv:1007.4883, Bibcode:2011MNRAS.410..190T, doi:10.1111/j.1365-2966.2010.17434.x, S2CID 118629873.
^ ^a ^b ^c ^d McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, arXiv:1208.2037, Bibcode:2012MNRAS.427..343M, doi:10.1111/j.1365-2966.2012.21873.x, S2CID 118665352.
^ Lefever, K.; et al. (June 2010), "Spectroscopic determination of the fundamental parameters of 66 B-type stars in the field-of-view of the CoRoT satellite", Astronomy and Astrophysics, 515: A74, arXiv:0910.2851, Bibcode:2010A&A...515A..74L, doi:10.1051/0004-6361/200911956, S2CID 54028925.
^ "tau08 Eri", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 2016-10-13.
^ ^a ^b Szewczuk, W.; Daszyńska-Daszkiewicz, J. (June 2015), "Identification of pulsational modes in rotating slowly pulsating B-type stars", Monthly Notices of the Royal Astronomical Society, 450 (2): 1585–1603, arXiv:1504.04490, Bibcode:2015MNRAS.450.1585S, doi:10.1093/mnras/stv715.
^ Mathys, G.; Manfroid, J.; Renson, P. (March 1986). "Photometric variability of some early-type stars". Astronomy and Astrophysics, Suppl. Ser. 63: 403–416. Bibcode:1986A&AS...63..403M. Retrieved 24 December 2024.
^ Bagnulo, S.; Landstreet, J. D.; Fossati, L.; Kochukhov, O. (February 2012), "Magnetic field measurements and their uncertainties: the FORS1 legacy", Astronomy & Astrophysics, 538: 22, arXiv:1112.3969, Bibcode:2012A&A...538A.129B, doi:10.1051/0004-6361/201118098, S2CID 119199060, A129.