Alpha Piscium
 Location of α Piscium(circled) |
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| Observation data Epoch J2000.0 Equinox J2000.0 |
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|---|---|
| Constellation | Pisces |
| Right ascension | 02h 02m 02.81972s |
| Declination | +02° 45′ 49.5410″ |
| Apparent magnitude (V) | 3.82 (+4.33 + 5.23) |
| Distance | 139 ± 1.6 ly (46.2 ± 0.5 pc) |
| Spectral type | A0pSiSr + A3m |
| Other designations | |
Alpha Piscium (α Piscium, abbreviated Alpha Psc, α Psc), also named Alrescha, is a binary star in the equatorial constellation of Pisces.
The system is about 139 light years from the Sun. It comprises a close binary with angular separation of presently 1.8" between the components. The main star or primary is of magnitude +4.33 and spectral type A0p, while the companion or secondary is magnitude 5.23 and belongs to spectral class A3m. The two stars take more than 700 years to orbit one another and they will make their closest approach to each other around 2060. One or both of the stars may be a spectroscopic binary as well. The stars have masses of 2.3 and 1.8 solar masses respectively and shine with a total luminosity of 31 and 12 times that of the Sun.
α Piscium (Latinised to Alpha Piscium) is the star's Bayer designation.
The system bore the traditional name Alrescha (alternatively Al Rescha, Alrischa, Alrisha) derived from the Arabic الرشآء al-rišā’ "the well rope" and less commonly Kaitain and Okda, the latter from the Arabic عقدة ‘uqdah "knot". In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016 included a table of the first two batches of names approved by the WGSN; which included Alrescha for this star.
In Chinese, 外屏 (Wài Píng), meaning Outer Fence, refers to an asterism consisting of Alpha Piscium, Delta Piscium, Epsilon Piscium, Zeta Piscium, Mu Piscium, Nu Piscium and Xi Piscium. Consequently, Alpha Piscium itself is known as 外屏七 (Wài Píng qī, English: the Seventh Star of Outer Fence.)
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