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Tau8 Eridani 
Summary
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]
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Eridanus |
| Right ascension | 03h 53m 42.70302s[2] |
| Declination | −24° 36′ 44.0309″[2] |
| Apparent magnitude (V) | 4.63 - 4.65[3] |
| Characteristics | |
| Spectral type | B6 V[4] |
| U−B color index | −0.48[5] |
| B−V color index | −0.13[5] |
| Variable type | SPB[3] |
| Astrometry | |
| Radial velocity (Rv) | +23[6] km/s |
| Proper motion (μ) | RA: +31.28[2] mas/yr Dec.: −7.49[2] mas/yr |
| Parallax (π) | 8.65 ± 0.30 mas[2] |
| Distance | 380 ± 10 ly (116 ± 4 pc) |
| Absolute magnitude (MV) | −0.67[7] |
| Orbit[8] | |
| 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[9] M☉ |
| Luminosity | 256[10] L☉ |
| Surface gravity (log g) | 4.00[11] cgs |
| Temperature | 11,858[10] K |
| Rotational velocity (v sin i) | 30[4] km/s |
| Age | 32.8±9.9[9] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
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] 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.[14]
References edit
- ^ 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.
- ^ 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.