Phi Piscium, Latinized from φ Piscium, is a quadruple star[6] system approximately 380 light years away in the constellation Pisces. It consists of Phi Piscium A, with a spectral type of K0III, and Phi Piscium B.[5] Phi Piscium A possesses a surface temperature of 3,500 to 5,000 kelvins. Some suggest the only visible companion in the Phi Piscium B sub-system is a late F dwarf star, while others suggest it is a K0 star. The invisible component of the Phi Piscium B sub-system is proposed to have a spectral type of M2V.[7] The star system has a period of about 20½ years and has a notably high eccentricity of 0.815.[4]
  | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Pisces |
| Right ascension | 01h 13m 44.94617s[1] |
| Declination | +24° 35′ 01.3249″[1] |
| Apparent magnitude (V) | 4.676 (A)/9.11 (B) |
| Characteristics | |
| φ Psc A | |
| Spectral type | K0III[2] |
| U−B color index | +0. |
| B−V color index | +1.03 |
| φ Psc B | |
| Spectral type | K0 |
| U−B color index | +0.25 |
| B−V color index | +0.92 |
| Astrometry | |
| Radial velocity (Rv) | 5.9 km/s |
| Proper motion (μ) | RA: 16.901[1] mas/yr Dec.: −21.415[1] mas/yr |
| Parallax (π) | 8.1541 ± 0.2028 mas[1] |
| Distance | 400 ± 10 ly (123 ± 3 pc) |
| Absolute magnitude (MV) | −0.67[3] |
| Orbit[4] | |
| Companion | φ Psc B |
| Period (P) | 7473±3 d yr |
| Eccentricity (e) | 0.815±0.005 |
| Argument of periastron (ω) (secondary) | 71.9±1.7° |
| Details | |
| A | |
| Radius | 23.63+0.66 −1.36[1] R☉ |
| Luminosity | 249.6±7.1[1] L☉ |
| Surface gravity (log g) | 2.75[2] cgs |
| Temperature | 4,720+142 −65[1] K |
| Metallicity [Fe/H] | −0.08[3] dex |
| Other designations | |
| Database references | |
| SIMBAD | data |
Naming
In Chinese, 奎宿 (Kuí Sù), meaning Legs (asterism), refers to an asterism consisting of refers to an asterism consisting of φ Piscium, η Andromedae, 65 Piscium, ζ Andromedae, ε Andromedae, δ Andromedae, π Andromedae, ν Andromedae, μ Andromedae, β Andromedae, σ Piscium, τ Piscium, 91 Piscium, υ Piscium, χ Piscium and ψ¹ Piscium. Consequently, φ Piscium itself is known as 奎宿十四 (Kuí Sù shí sì, English: the Fourteenth Star of Legs.)[8]