Sigma Leonis
Star in the constellation Leo
From Wikipedia, the free encyclopedia
Sigma Leonis, Latinized from σ Leonis, is a blue-white hued star in the zodiac constellation Leo that is visible to the naked eye with an apparent visual magnitude of 4.0.[3] Its annual parallax shift of 15.24 mas as seen from Earth implies a distance around 210 light years from the Sun. It is moving closer to the Sun with a radial velocity of –5 km/s.[7]
 | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Leo[1] |
| Right ascension | 11h 21m 08.1943s[2] |
| Declination | +06° 01′ 45.558″[2] |
| Apparent magnitude (V) | 4.046[3] |
| Characteristics | |
| Evolutionary stage | main sequence[4] |
| Spectral type | B9.5 Vs[5] |
| U−B color index | −0.12[6] |
| B−V color index | −0.06[6] |
| Astrometry | |
| Radial velocity (Rv) | −5.3[7] km/s |
| Proper motion (μ) | RA: −91.76[2] mas/yr Dec.: −12.83[2] mas/yr |
| Parallax (π) | 15.24±0.81 mas[2] |
| Distance | 210 ± 10 ly (66 ± 3 pc) |
| Absolute magnitude (MV) | −0.10[1] |
| Details | |
| Mass | 2.76[8] M☉ |
| Radius | 3.07±0.23[9] R☉ |
| Luminosity | 133[1] L☉ |
| Surface gravity (log g) | 3.83±0.03[10] cgs |
| Temperature | 11,000±1,000[9] K |
| Metallicity [Fe/H] | +0.0[11] dex |
| Rotational velocity (v sin i) | 70[12] km/s |
| Age | 293[8] Myr |
| Other designations | |
| σ Leo, 77 Leo, BD+06°2437, FK5 427, HD 98664, HIP 55434, HR 4386, SAO 118804[13] | |
| Database references | |
| SIMBAD | data |
Chini et al. (2012) list this as a single-lined spectroscopic binary system.[5] The visible component has a stellar classification of B9.5 Vs,[5] indicating it is a B-type main-sequence star. It is a suspected magnetic Ap star that shows an abundance anomaly with the element silicon.[14] Sigma Leonis has an estimated 2.76 times the mass of the Sun[8] and 3.07 times the Sun's radius.[9] It is about 293 million years old[8] with a projected rotational velocity of 70 km/s.[12] The star is radiating 133 times the Sun's luminosity from its photosphere[1] at an effective temperature of 11,000 K.[9]
Name
In Chinese, 太微右垣 (Tài Wēi Yòu Yuán), meaning Right Wall of Supreme Palace Enclosure, refers to an asterism consisting of σ Leonis, β Virginis, ι Leonis, θ Leonis and δ Leonis.[15] Consequently, the Chinese name for σ Leonis itself is 太微右垣二 (Tài Wēi Yòu Yuán èr, English: the Second Star of Right Wall of Supreme Palace Enclosure.),[16] representing 西上將 (Xīshǎngjiāng), meaning The First Western General.[17] 西上將 (Xīshǎngjiāng), spelled Shang Tseang by R.H. Allen, means "the Higher General".[18]