Sigma Librae
Star in the constellation Libra / From Wikipedia, the free encyclopedia
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Sigma Librae (σ Librae, abbreviated Sigma Lib, σ Lib) is a binary star[11] in the constellation of Libra. The apparent visual magnitude is +3.29,[4] making it visible to the naked eye. Based upon parallax measurements, this system is at a distance of roughly 288 light-years (88 parsecs) from the Sun, with a 2% margin of error.[1] At that distance, the visual magnitude is diminished by 0.20 ± 0.17 from extinction caused by intervening gas and dust.[9]
Quick Facts Constellation, Right ascension ...
Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
---|---|
Constellation | Libra |
Right ascension | 15h 04m 04.21608s[1] |
Declination | –25° 16′ 55.0606″[1] |
Apparent magnitude (V) | 3.20 - 3.46[2] |
Characteristics | |
Spectral type | M2.5III[3] |
U−B color index | +1.94[4] |
B−V color index | +1.70[4] |
Variable type | SRb[2] |
Astrometry | |
Radial velocity (Rv) | –4.2[5] km/s |
Proper motion (μ) | RA: –71.16[1] mas/yr Dec.: −43.34[1] mas/yr |
Parallax (π) | 11.31 ± 0.25 mas[1] |
Distance | 288 ± 6 ly (88 ± 2 pc) |
Absolute magnitude (MV) | –1.5[6] |
Details | |
Mass | 2.2[7] M☉ |
Radius | 108[8] R☉ |
Luminosity | 1,820[7] L☉ |
Surface gravity (log g) | 0.9 ± 0.3[9] cgs |
Temperature | 3,596[7] K |
Metallicity [Fe/H] | 0.00[9] dex |
Other designations | |
Database references | |
SIMBAD | data |
Close
The two components are designated Sigma Librae A (officially named Brachium /ˈbreɪkiəm/,[12] the traditional name for the system)[13] and B.