Tau5 Eridani

τ5 Eridani


Location of τ5 Eridani (circled)

Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Eridanus
Right ascension 03h 33m 47.27613s[1]
Declination −21° 37′ 58.3830″[1]
Apparent magnitude (V) 4.26[2]
Characteristics
Spectral type B0 V + B9 V[3]
U−B color index 0.35[2]
B−V color index −0.09[2]
Astrometry
Proper motion (μ) RA: +44.94[1] mas/yr
Dec.: −28.16[1] mas/yr
Parallax (π)11.12 ± 0.21[1] mas
Distance293 ± 6 ly
(90 ± 2 pc)
Orbit[4]
Period (P)6.2236 d
Eccentricity (e)0.2
Periastron epoch (T)2424446.548 JD
Argument of periastron (ω)
(secondary)		313°
Semi-amplitude (K1)
(primary)		107 km/s
Semi-amplitude (K2)
(secondary)		103 km/s
Details
τ5 Eri A
Mass3.30+0.24
−0.20[5] M☉
Radius3.2[3] R☉
Luminosity188[6] L☉
Surface gravity (log g)4.00±0.15[5] cgs
Temperature12,514±425[7] K
Rotational velocity (v sin i)55±8[3] km/s
Age157+23
−45[5] Myr
τ5 Eri B
Radius2.6[3] R☉
Rotational velocity (v sin i)50±8[3] km/s
Other designations
τ5 Eridani, τ5 Eri, 19 Eridani, BD-22° 628, HD 22203, HIP 16611, HR 1088, SAO 168634.[8]
Database references
SIMBADdata

Tau5 Eridani (τ5 Eri) is a binary star system in the constellation Eridanus. It is visible to the naked eye with a combined apparent visual magnitude of 4.26.[2] The distance to this system, as estimated using the parallax technique, is around 293 light years.[1]

Tau5 Eridani is a double-lined spectroscopic binary system.[9] The two stars orbit each other closely with a period of 6.2 days and an eccentricity of 0.2.[4] On average, the two stars are separated by around 0.183 AU.[3]

The primary component is a B-type main sequence star with a stellar classification of B0 V.[3] It is around 157 million years old and is spinning with a projected rotational velocity of 55 km/s.[3] The star has around 3.3[5] times the mass of the Sun and 3.2[3] times the Sun's radius. It radiates 188[6] times the solar luminosity from an outer atmosphere at an effective temperature of 12,514 K.[7]

The secondary component has a stellar classification of B9 V.[3] It is slightly smaller, with an estimated size equal to 2.6 times the radius of the Sun.[3]

Although τ5 Eridani has no bright visual companion stars, the galaxy IC 1953 is less than 10' away. It is one of the brighter members of a loose group of galaxies called the Eridanus Group scattered around the components of τ Eridani.

References

  1. 1 2 3 4 5 6 van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, Bibcode:2007A&A...474..653V, arXiv:0708.1752 Freely accessible, doi:10.1051/0004-6361:20078357.
  2. 1 2 3 4 Mermilliod, J.-C. (1986), Compilation of Eggen's UBV data, transformed to UBV (unpublished), SIMBAD, Bibcode:1986EgUBV........0M.
  3. 1 2 3 4 5 6 7 8 9 10 11 Howe, K. S.; Clarke, C. J. (January 2009), "An analysis of v sin (i) correlations in early-type binaries", Monthly Notices of the Royal Astronomical Society, 392 (1): 448–454, Bibcode:2009MNRAS.392..448H, doi:10.1111/j.1365-2966.2008.14073.x.
  4. 1 2 Pourbaix, D.; et al. (2004), "SB9: The ninth catalogue of spectroscopic binary orbits", Astronomy and Astrophysics, 424 (2): 727, Bibcode:2004A&A...424..727P, arXiv:astro-ph/0406573 Freely accessible, doi:10.1051/0004-6361:20041213.
  5. 1 2 3 4 Gullikson, Kevin; et al. (August 2016), "The Close Companion Mass-ratio Distribution of Intermediate-mass Stars", The Astronomical Journal, 152 (2): 13, Bibcode:2016AJ....152...40G, arXiv:1604.06456 Freely accessible, doi:10.3847/0004-6256/152/2/40, 40.
  6. 1 2 McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, Bibcode:2012MNRAS.427..343M, arXiv:1208.2037 Freely accessible, doi:10.1111/j.1365-2966.2012.21873.x.
  7. 1 2 David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, Bibcode:2015ApJ...804..146D, arXiv:1501.03154 Freely accessible, doi:10.1088/0004-637X/804/2/146.
  8. ↑ "tau05 Eri -- Spectroscopic binary", SIMBAD Astronomical Database, Centre de Données astronomiques de Strasbourg, retrieved 2016-10-13.
  9. ↑ van Rensbergen, W.; et al. (February 2006), "Evolution of interacting binaries with a B type primary at birth", Astronomy and Astrophysics, 446 (3): 1071–1079, Bibcode:2006A&A...446.1071V, doi:10.1051/0004-6361:20053543.
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