Phi Centauri
Phi Centauri, Latinized from φ Centauri, is a blue-white hued star in the southern constellation Centaurus. It is visible to the naked eye with an apparent visual magnitude of +3.7. The annual parallax shift is 6.21 mas 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.
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Centaurus |
| Right ascension | 13h 58m 16.27s |
| Declination | −42° 06′ 02.7″ |
| Apparent magnitude (V) | +3.745 |
| Characteristics | |
| Spectral type | B2 IV |
| U−B color index | −0.851 |
| B−V color index | −0.222 |
| Astrometry | |
| Radial velocity (Rv) | +5.3±1.5 km/s |
| Proper motion (μ) | RA: −22.77±0.15 mas/yr Dec.: −20.13±0.12 mas/yr |
| Parallax (π) | 6.21 ± 0.17 mas |
| Distance | 530 ± 10 ly (161 ± 4 pc) |
| Absolute magnitude (MV) | −2.20 |
| Details | |
| Mass | 8.5±0.3 M☉ |
| Radius | 4.19±0.35 R☉ |
| Luminosity | 4,000 L☉ |
| Surface gravity (log g) | 4.08±0.07 cgs |
| Temperature | 21,638±388 K |
| Rotational velocity (v sin i) | 79 km/s |
| Age | 18.0±3.2 Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
This is a B-type subgiant star with a stellar classification of B2 IV. It has no known companions, but does show radial velocity variations and higher order pulsations in the spectrum. The star is just 18 million years old with 8.5 times the mass of the Sun and has 4.2 times the Sun's radius. It is radiating around 4,000 times the Sun's luminosity from its photosphere at an effective temperature of about 21,638 K.
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.