Phi Centauri
Star in the constellation Centaurus
From Wikipedia, the free encyclopedia
Phi Centauri is a blue-white hued star in the southern constellation Centaurus. Its name is a Bayer designation that is Latinized from φ Centauri, and abbreviated Phi Cen or φ Cen. This star is visible to the naked eye with an apparent visual magnitude of +3.7.[1] The annual parallax shift is 6.21 mas[2] as measured from Earth, which yields a distance estimate of around 530 light years. It is moving further from the Sun with a radial velocity of +5 km/s.[5]
 | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Centaurus[1] |
| Right ascension | 13h 58m 16.27s[2] |
| Declination | −42° 06′ 02.7″[2] |
| Apparent magnitude (V) | +3.745[1] |
| Characteristics | |
| Spectral type | B2 IV[3] |
| U−B color index | −0.851[4] |
| B−V color index | −0.222[4] |
| Astrometry | |
| Radial velocity (Rv) | +5.3±1.5[5] km/s |
| Proper motion (μ) | RA: −22.77±0.15[2] mas/yr[2] Dec.: −20.13±0.12 mas/yr[2] |
| Parallax (π) | 6.21±0.17 mas[2] |
| Distance | 530 ± 10 ly (161 ± 4 pc) |
| Absolute magnitude (MV) | −2.20[1] |
| Details | |
| Mass | 8.5±0.3[3] M☉ |
| Radius | 4.19±0.35[6] R☉ |
| Luminosity | 4,000[7] L☉ |
| Surface gravity (log g) | 4.08±0.07[6] cgs |
| Temperature | 21,638±388[6] K |
| Rotational velocity (v sin i) | 79[8] km/s |
| Age | 18.0±3.2[3] Myr |
| Other designations | |
| φ Cen, CD−41°8329, GC 18874, HD 121743, HIP 68245, HR 5248, SAO 224577[9] | |
| Database references | |
| SIMBAD | data |
This is a B-type subgiant star with a stellar classification of B2 IV.[3] It has no known companions, but does show radial velocity variations and higher order pulsations in the spectrum.[10] The star is just 18[3] million years old with 8.5[3] times the mass of the Sun and has 4.2[6] times the Sun's radius. It is radiating around 4,000[7] times the Sun's luminosity from its photosphere at an effective temperature of about 21,638 K.[6]
This star is a proper motion member of the Upper Centaurus–Lupus sub-group in the Scorpius–Centaurus OB association, the nearest such co-moving association of massive stars to the Sun.[7]