Epsilon Leonis
 | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Leo |
| Right ascension | 09h 45m 51.07330s[1] |
| Declination | 23° 46′ 27.3208″[1] |
| Apparent magnitude (V) | 2.98[2] |
| Characteristics | |
| Spectral type | G1 II[3] |
| U−B color index | +0.47[2] |
| B−V color index | +0.808[4] |
| Variable type | Cepheid |
| Astrometry | |
| Radial velocity (Rv) | 4.86 ± 0.33[4] km/s |
| Proper motion (μ) | RA: –45.61[1] mas/yr Dec.: –9.21[1] mas/yr |
| Parallax (π) | 13.22 ± 0.15 mas[1] |
| Distance | 247 ± 3 ly (75.6 ± 0.9 pc) |
| Absolute magnitude (MV) | –1.49[5] |
| Details | |
| Mass | 4.01[5] M☉ |
| Radius | 21[4] R☉ |
| Luminosity | 288[4] L☉ |
| Surface gravity (log g) | 2.2[4] cgs |
| Temperature | 5,248[4] K |
| Metallicity [Fe/H] | –0.28[4] dex |
| Rotational velocity (v sin i) | 8.1[4] km/s |
| Age | 162[5] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Epsilon Leonis (ε Leo, ε Leonis) is the fifth brightest star in the constellation Leo, consistent with its Bayer designation Epsilon. The star has the traditional names Ras Elased (Australis), Asad Australis and Algenubi, all of which derive from the Arabic رأس الأسد الجنوبي rās al-’asad al-janūbī, which means "the southern (star) of the lion's head"; australis is Latin for "southern".
Properties
Epsilon Leonis has a stellar classification of G1 II, with the luminosity class of II indicating that, at an age of 162 million years,[5] it has evolved into a bright giant. It is much larger and brighter than the Sun with a luminosity 288 times and a radius 21 times solar.[4] Consequently, its absolute magnitude is actually –1.49,[5] making it one of the more luminous stars in the constellation, significantly more than its alpha star, Regulus. Algenubi's apparent brightness, though, is only 2.98.[2] Given its distance of about 247 light-years (76 parsecs), the star is more than 3 times the distance from the Sun than Regulus. At this distance, the visual magnitude of Epsilon Leonis is reduced by 0.03 as a result of extinction caused by intervening gas and dust.[5]
Algenubi exhibits the characteristics of a Cepheid-like variable, changing by an amplitude of 0.3 magnitude every few days.[6][7] It has around four times the mass of the Sun and a projected rotational velocity of 8.1 km s−1.[4] Based upon its iron abundance, the metallicity of this star's outer atmosphere is only around 52% of the Sun's. That is, the abundance of elements other than hydrogen and helium is about half that in the Sun.[4]
See also
- Lists of stars in the constellation Leo
- Class G Stars
- Variable star
- Algenubi in fiction
References
- ^ a b c d e van Leeuwen, Floor (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752v1, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357 Note: see VizieR catalogue I/311.
- ^ a b c Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99), Bibcode:1966CoLPL...4...99J
- ^ "eps Leo -- Variable Star", SIMBAD Astronomical Object Database, Centre de Données astronomiques de Strasbourg, retrieved 2010-05-10
- ^ a b c d e f g h i j k Massarotti, Alessandro; et al. (January 2008), "Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity", The Astronomical Journal, 135 (1): 209–231, Bibcode:2008AJ....135..209M, doi:10.1088/0004-6256/135/1/209
- ^ a b c d e f Takeda, Yoichi; Sato, Bun'ei; Murata, Daisuke (August 2008), "Stellar parameters and elemental abundances of late-G giants", Publications of the Astronomical Society of Japan, 60 (4): 781–802, arXiv:0805.2434, Bibcode:2008PASJ...60..781T, doi:10.1093/pasj/60.4.781
- ^ Andrievsky, S. M. (July 1998), "BA II lines as luminosity indicators: s-Cepheids and non-variable supergiants", Astronomische Nachrichten, 319 (4): 239–240, Bibcode:1998AN....319..239A, doi:10.1002/asna.2123190405
- ^ Kaler, James B., "ALGENUBI (Epsilon Leonis)", Stars, University of Illinois, retrieved 2010-05-10
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