Astronomy:Kappa Eridani
| Observation data Equinox J2000.0]] (ICRS) | |
|---|---|
| Constellation | Eridanus |
| Right ascension | 02h 26m 59.12177s[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[1] mas |
| 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 | |
| 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
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, doi:10.1051/0004-6361:20078357, Bibcode: 2007A&A...474..653V.
- ↑ 2.0 2.1 2.2 2.3 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.
- ↑ 3.0 3.1 3.2 3.3 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, doi:10.1111/j.1365-2966.2006.10655.x, Bibcode: 2006MNRAS.371..252L.
- ↑ 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, doi:10.1051/0004-6361/201219219, A61, Bibcode: 2012A&A...546A..61D.
- ↑ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A.
- ↑ 6.0 6.1 Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, 1 (3rd ed.), Birkhäuser, ISBN 3-540-29692-1, https://books.google.com/books?id=OvTjLcQ4MCQC&pg=PA41.
The radius (R*) is given by:- [math]\displaystyle{ \begin{align} 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{align} }[/math]
- ↑ 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, doi:10.1051/0004-6361:20000451, Bibcode: 2001A&A...367..521P.
- ↑ 8.0 8.1 Niemczura, E. (June 2003), "Metallicities of the SPB stars from the IUE ultraviolet spectra", Astronomy and Astrophysics 404 (2): 689–700, doi:10.1051/0004-6361:20030546, Bibcode: 2003A&A...404..689N.
- ↑ "kap Eri". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=kap+Eri.
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