 A light curve for Tau Eridani plotted from TESS data | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Eridanus |
| Right ascension | 03 59 55.48381 |
| Declination | −24° 00′ 58.3798″ |
| Apparent magnitude (V) | 4.63 |
| Characteristics | |
| Spectral type | B9.5V Si |
| U−B color index | −0.40 |
| B−V color index | −0.13 |
| Variable type | α CVn |
| Astrometry | |
| Radial velocity (Rv) | 25.5±0.5 km/s |
| Proper motion (μ) | RA: +12.12 mas/yr Dec.: +16.48 mas/yr |
| Parallax (π) | 9.96 ± 0.22 mas |
| Distance | 327 ± 7 ly (100 ± 2 pc) |
| Absolute magnitude (MV) | −0.44 |
| Orbit | |
| Period (P) | 5.95382 days |
| Eccentricity (e) | 0.129 |
| Periastron epoch (T) | 246991.65 JD |
| Argument of periastron (ω) (secondary) | 183.2° |
| Semi-amplitude (K1) (primary) | 40.0 km/s |
| Semi-amplitude (K2) (secondary) | 89.9 km/s |
| Details | |
| τ Eri A | |
| Mass | 3.6 M☉ |
| Radius | 3.06 R☉ |
| Luminosity | 209 L☉ |
| Surface gravity (log g) | 4.11±0.11 cgs |
| Temperature | 12,580 K |
| Rotational velocity (v sin i) | 26.8 km/s |
| Age | 140 Myr |
| τ Eri B | |
| Mass | 1.6 M☉ |
| Radius | 1.5 R☉ |
| Luminosity | 6.3 L☉ |
| Temperature | 7530 K |
| Rotational velocity (v sin i) | 15 km/s |
| Other designations | |
| τ Eridani, τ Eri, 36 Eridani, CD−24° 2022, FK5 2287, HD 25267, HIP 18673, HR 1240, SAO 169017. | |
| Database references | |
| SIMBAD | data |
Tau Eridani (τ Eri) is a binary star in the constellation Eridanus. It is visible to the naked eye with an apparent visual magnitude of 4.63. The distance to this system can be estimated using the parallax method, which yields a value of roughly 327 light years.
This is a double-lined spectroscopic binary system with an orbital period of 5.95382 days and an eccentricity of 0.12. The primary component, τ Eri A, is a magnetic chemically peculiar star with a stellar classification of B9.5V Si, indicating that it is a B-type main sequence star that shows abundance anomalies in its silicon absorption lines. It is an Alpha² Canum Venaticorum variable with a rotational periodicity of 5.954 days. The averaged strength of the stellar effective magnetic field is 240.6±91.0 G.
The primary component Tau Eridani A has an estimated 326% the mass of the Sun and 3.1 times the Sun's radius. It shines with 166 times the solar luminosity from an outer atmosphere at an effective temperature of 10,866 K. The star is spinning with a projected rotational velocity of 30 km/s. The secondary star, designated Tau Eridani B, is a late A-type or early F-type star with a mass of 1.6 solar masses and an effective temperature of 7530 K.
References
- "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 8 December 2021.
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- De Bruijne, J. H. J.; Eilers, A.-C. (2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: A61, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, S2CID 59451347.
- ^ Woodcock, K. (2021), "τ Eri: a bright pulsating magnetic Bp star in a 5.95-d double-lined spectroscopic binary", Monthly Notices of the Royal Astronomical Society, 502 (4): 5200–5209, arXiv:2101.11732, Bibcode:2021MNRAS.502.5200W, doi:10.1093/mnras/stab338
- ^ North, P. (June 1998), "Do SI stars undergo any rotational braking?", Astronomy and Astrophysics, 334: 181–187, arXiv:astro-ph/9802286, Bibcode:1998A&A...334..181N.
- "tau09 Eri". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2016-10-13.
{{cite web}}: CS1 maint: postscript (link) - ^ Shulyak, D.; et al. (September 2014), "Interferometry of chemically peculiar stars: theoretical predictions versus modern observing facilities", Monthly Notices of the Royal Astronomical Society, 443 (2): 1629–1642, arXiv:1406.6093, Bibcode:2014MNRAS.443.1629S, doi:10.1093/mnras/stu1259.
- Bychkov, V. D.; et al. (February 2005), "A catalog of stellar magnetic rotational phase curves", Astronomy and Astrophysics, 430 (3): 1143–1154, Bibcode:2005A&A...430.1143B, doi:10.1051/0004-6361:20034563.
- ^ 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.
- 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.
