| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Libra |
| Right ascension | 15h37m 01.45020s[1] |
| Declination | −28° 08′ 06.2926″[1] |
| Apparent magnitude (V) | 3.628[2] |
| Characteristics | |
| Spectral type | K3 III[3] |
| U−B color index | +1.586[2] |
| B−V color index | +1.374[2] |
| Astrometry | |
| Radial velocity (Rv) | −24.9±0.7[4] km/s |
| Proper motion (μ) | RA: −12.82[1] mas/yr Dec.: −4.15[1] mas/yr |
| Parallax (π) | 14.58 ± 0.19 mas[1] |
| Distance | 224 ± 3 ly (68.6 ± 0.9 pc) |
| Absolute magnitude (MV) | −0.28[5] |
| Details[6] | |
| Mass | 1.67 M☉ |
| Radius | 31.5[7] R☉ |
| Luminosity | 309 L☉ |
| Surface gravity (log g) | 1.58 cgs |
| Temperature | 4,135±20 K |
| Metallicity [Fe/H] | −0.02 dex |
| Age | 3.14 Gyr |
| Other designations | |
υ Lib, 39 Lib, CD−27° 10464, FK5 579, HD 139063, HIP 76470, HR 5794, SAO 183619.[8] | |
| Database references | |
| SIMBAD | data |
Upsilon Librae (υ Lib, υ Librae) is the Bayer designation for a double star[9] in the zodiac constellation Libra. With an apparent visual magnitude of 3.628,[2] it is visible to the naked eye. The distance to this star, based upon an annual parallax shift of 14.58,[1] is around 224 light years. It has a magnitude 10.8 companion at an angular separation of 2.0 arc seconds along a position angle of 151°, as of 2002.[10]
The brighter component is an evolved K-type giant star with a stellar classification of K3 III.[3] The measured angular diameter, after correction for limb darkening, is 4.27±0.05 mas.[11] At the estimated distance of the star, this yields a physical size of about 31.5 times the radius of the Sun.[7] It has 1.67 times the mass of the Sun and radiates 309 times the solar luminosity from its outer atmosphere at an effective temperature of 4,135 K.[6] The star is about three billion years old.[6]
Upsilon Librae will be the brightest star in the night sky in about 2.3 million years,[12] and will peak in brightness with an apparent magnitude of –0.46.[12]
