Tau9 Eridani
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Eridanus |
| Right ascension | 03h 59m 55.48381s[1] |
| Declination | −24° 00′ 58.3798″[1] |
| Apparent magnitude (V) | 4.63[2] |
| Characteristics | |
| Spectral type | B9.5V Si[3] |
| U−B color index | −0.40[2] |
| B−V color index | −0.13[2] |
| Variable type | α2 CVn[4] |
| Astrometry | |
| Radial velocity (Rv) | 25.5±0.5[5] km/s |
| Proper motion (μ) | RA: +12.12[1] mas/yr Dec.: +16.48[1] mas/yr |
| Parallax (π) | 9.96 ± 0.22[1] mas |
| Distance | 327 ± 7 ly (100 ± 2 pc) |
| Absolute magnitude (MV) | −0.44[4] |
| Orbit[6] | |
| Period (P) | 5.9537 days |
| Eccentricity (e) | 0.1 |
| Periastron epoch (T) | 2417600.95 JD |
| Argument of periastron (ω) (secondary) | 151° |
| Semi-amplitude (K1) (primary) | 37.6 km/s |
| Details | |
| τ9 Eri A | |
| Mass | 3.26[7] M☉ |
| Radius | 3.26[7] R☉ |
| Luminosity | 166[8] L☉ |
| Surface gravity (log g) | 4.11±0.11[9] cgs |
| Temperature | 10,866[8] K |
| Rotational velocity (v sin i) | 30[10] km/s |
| Other designations | |
Tau9 Eridani (τ9 Eri) is a binary star in the constellation Eridanus. It is visible to the naked eye with an apparent visual magnitude of 4.63.[2] The distance to this system can be estimated using the parallax method, which yields a value of roughly 327 light years.[2]
This is a single-lined spectroscopic binary system with an orbital period of 5.9537 days and an eccentricity of 0.1.[6] The primary component, τ9 Eri A, is a magnetic chemically peculiar star[7] with a stellar classification of B9.5V Si,[3] indicating that it is a B-type main sequence star that shows abundance anomalies in its silicon absorption lines.[3] It is an Alpha² Canum Venaticorum variable[4] with a rotational periodicity of 5.954 days.[12] The averaged strength of the stellar effective magnetic field is 240.6±91.0 G.[3]
Tau9 Eridani A has an estimated 326%[7] the mass of the Sun and 3.1 times the Sun's radius.[9] It shines with 166[8] times the solar luminosity from a outer atmosphere at an effective temperature of 10,866 K.[8] The star is spinning with a projected rotational velocity of 30 km/s.[10]
References
- 1 2 3 4 5 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. - 1 2 3 4 5 Mermilliod, J.-C. (1986), Compilation of Eggen's UBV data, transformed to UBV (unpublished), SIMBAD, Bibcode:1986EgUBV........0M.
- 1 2 3 4 Bychkov, V. D.; et al. (April 2009), "Catalogue of averaged stellar effective magnetic fields - II. Re-discussion of chemically peculiar A and B stars", Monthly Notices of the Royal Astronomical Society, 394 (3): 1338−1350, Bibcode:2009MNRAS.394.1338B, doi:10.1111/j.1365-2966.2008.14227.x.
- 1 2 3 Dubath, P.; et al. (2011), "Random forest automated supervised classification of Hipparcos periodic variable stars", Monthly Notices of the Royal Astronomical Society, 414 (3): 2602, Bibcode:2011MNRAS.414.2602D, doi:10.1111/j.1365-2966.2011.18575.x.
- ↑ De Bruijne, J. H. J.; Eilers, A.-C. (2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: A61, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219.
- 1 2 Pourbaix, D.; et al. (2004), "SB9: The ninth catalogue of spectroscopic binary orbits", Astronomy and Astrophysics, 424 (2): 727, arXiv:astro-ph/0406573, Bibcode:2004A&A...424..727P, doi:10.1051/0004-6361:20041213.
- 1 2 3 4 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.
- 1 2 3 4 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.
- 1 2 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.
- 1 2 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.
- ↑ "tau09 Eri -- Variable Star of alpha2 CVn type", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2016-10-13.
- ↑ Bychkov, V. D.; et al. (February 2005), "A catalog of stellar magnetic rotational phase curves", Astronomy and Astrophysics, 430: 1143−1154, Bibcode:2005A&A...430.1143B, doi:10.1051/0004-6361:20034563.