Pi Capricorni
Star in the constellation Capricornus
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Pi Capricorni is a triple star system in the southern constellation of Capricornus. It has the traditional star name Oculus (meaning eye in Latin);[11] Pi Capricorni is its Bayer designation, which is Latinized from Ï Capricorni and abbreviated Pi Cap or Ï Cap. This system appears blue-white in hue and is visible to the naked eye as a 5th magnitude star.[2] It is located approximately 650 light-years (200 pc) 660 light years distant from the Sun based on parallax,[1] but is drifting closer with a radial velocity of â13 km/s.[5] The proximity of this star to the ecliptic means it is subject to lunar occultation.[12]
 | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Capricornus |
| Right ascension | 20h 27m 19.202s[1] |
| Declination | â18° 12â² 42.10â³[1] |
| Apparent magnitude (V) | +5.096[2] |
| Characteristics | |
| Spectral type | B8 II-III[3] or B3-5 V[4] |
| UâB color index | â0.311[2] |
| BâV color index | +0.013[2] |
| Astrometry | |
| Radial velocity (Rv) | â13[5] km/s |
| Proper motion (μ) | RA: +16.560 mas/yr[1] Dec.: â17.375 mas/yr[1] |
| Parallax (Ï) | 5.0291±0.1530 mas[1] |
| Distance | 650 ± 20 ly (199 ± 6 pc) |
| Absolute magnitude (MV) | â1.01[6] |
| Details | |
| Ï Cap Aa | |
| Mass | 5.9±0.1[7] Mâ |
| Luminosity | 238[8] Lâ |
| Temperature | 9,623[8] K |
| Rotational velocity (v sin i) | 30[9] km/s |
| Age | 43.4±7.8[7] Myr |
| Other designations | |
| Oculus, Ï Cap, 10 Cap, BDâ18°5685, HD 194636, HIP 100881, HR 7814, SAO 163592, ADS 13860, WDS J20273-1813AB[10] | |
| Database references | |
| SIMBAD | data |
In Chinese, ç宿 (Niú Su), meaning Ox (asterism), refers to an asterism consisting of Ï Capricorni, β Capricorni, α2 Capricorni, ξ2 Capricorni, ο Capricorni and Ï Capricorni.[13] Consequently, the Chinese name for Ï Capricorni itself is ç宿å (Niú Su sì, English: the Fourth Star of Ox.)[14]
The primary member, component A, is a spectroscopic binary whose two components are separated by 0.1 arcseconds. The brighter of the two, component Aa, is a blue-white B-type bright giant or main sequence star with an apparent magnitude of +5.08. It is around 43 million years old with six times the mass of the Sun.[7] The star is radiating 238 times the Sun's luminosity from its photosphere at an effective temperature of 9,623 K.[8] The third member, component B, is an eighth magnitude star at an angular separation of 3.4â³ from the primary.[15]