Kappa Eridani

κ Eridani

Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Eridanus
Right ascension	02^h 26^m 59.12177^s[1]
Declination	−47° 42′ 13.8247″[1]
Apparent magnitude (V)	4.25[2]
Characteristics
Spectral type	B7 IV[3]
U−B color index	−0.50[2]
B−V color index	−0.14[2]
Astrometry
Radial velocity (Rv)	+25.5±0.5[4] km/s
Proper motion (μ)	RA: +19.32[1] mas/yr Dec.: −5.54[1] mas/yr
Parallax (π)	6.42 ± 0.15 mas[1]
Distance	510 ± 10 ly (156 ± 4 pc)
Absolute magnitude (MV)	−1.72[5]
Details[3]
Mass	5.0±0.8 M☉
Radius	6[6][7] R☉
Luminosity	1,175 L☉
Surface gravity (log g)	3.5±0.1 cgs
Temperature	14,700±400 K
Metallicity [Fe/H]	0.02±0.06[8] dex
Rotational velocity (v sin i)	10±8 km/s
Age	93 Myr
Other designations
κ Eri, CD-48° 637, FK5 86, HD 15371, HIP 11407, HR 721, SAO 215906.[9]
Database references
SIMBAD	data

Kappa Eridani, Latinized from κ Eridani, is a solitary star in the constellation Eridanus. With an apparent visual magnitude of 4.25,^[2] it is bright enough to be visible to the naked eye on a dark night. Based upon an annual parallax shift of 0.00642 arc seconds,^[1] it is roughly 510 light years distant from the Sun.

This appears to be an evolving B-type subgiant star with a stellar classification of B7 IV.^[3] The measured angular diameter is 0.346±0.008 mas.^[8] At an estimated distance of Kappa Eridani, this yields a physical size of about six times the radius of the Sun.^[6] It has five times the Sun's mass, and radiates 1,175 times the solar luminosity from its outer atmosphere at an effective temperature of 14,700 K. Kappa Eridani is spinning with a projected rotational velocity of 10 km/s and is around 93 million years old.^[3]

References

1. 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.
2. 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.
3. Levenhagen, R. S.; Leister, N. V. (2006), "Spectroscopic Analysis of Southern B and Be Stars", Monthly Notices of the Royal Astronomical Society, 371 (1): 252–62, arXiv:astro-ph/0606149, Bibcode:2006MNRAS.371..252L, doi:10.1111/j.1365-2966.2006.10655.x, S2CID 16492030.
4. de Bruijne, J. H. J.; Eilers, A.-C. (October 2012), "Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project", Astronomy & Astrophysics, 546: 14, arXiv:1208.3048, Bibcode:2012A&A...546A..61D, doi:10.1051/0004-6361/201219219, S2CID 59451347, A61.
5. 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.
6. Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, vol. 1 (3rd ed.), Birkhäuser, ISBN 3-540-29692-1.
   The radius (R_*) is given by:

   ${\displaystyle {\begin{aligned}2\cdot R_{*}&={\frac {(155.8\cdot 0.346\cdot 10^{-3})\ {\text{AU}}}{0.0046491\ {\text{AU}}/R_{\bigodot }}}\\&\approx 11.6\cdot R_{\bigodot }\end{aligned}}}$

7. Pasinetti Fracassini, L. E.; et al. (2001), "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics", Astronomy & Astrophysics, 367 (2): 521–24, arXiv:astro-ph/0012289, Bibcode:2001A&A...367..521P, doi:10.1051/0004-6361:20000451, S2CID 425754.
8. Niemczura, E. (June 2003), "Metallicities of the SPB stars from the IUE ultraviolet spectra", Astronomy and Astrophysics, 404 (2): 689–700, Bibcode:2003A&A...404..689N, doi:10.1051/0004-6361:20030546.
9. "kap Eri". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2016-10-30.