Pi Capricorni

Pi Capricorni, Latinized from π Capricorni, is a triple star system in the southern constellation of Capricornus. It has the traditional star name Oculus (meaning eye in Latin).^[12] This system appears blue-white in hue and is visible to the naked eye as a 5th magnitude star.^[2] It is located approximately 660 light years distant from the Sun based on parallax,^[6] but is drifting closer with a radial velocity of −13 km/s.^[5]

Pi Capricorni

Location of π Capricorni (circled)
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Capricornus
Right ascension	20h 27m 19.21088s[1]
Declination	−18° 12′ 42.1980″[1]
Apparent magnitude (V)	+5.096[2]
Characteristics
Spectral type	B8 II-III[3] or B3-5 V[4]
U−B color index	−0.311[2]
B−V color index	+0.013[2]
Astrometry
Radial velocity (Rv)	−13[5] km/s
Proper motion (μ)	RA: +16.914[6] mas/yr Dec.: −16.983[6] mas/yr
Parallax (π)	4.9614±0.3495 mas[6]
Distance	660 ± 50 ly (200 ± 10 pc)
Absolute magnitude (MV)	−1.01[7]
Details
π Cap Aa
Mass	5.9±0.1[8] M☉
Luminosity	238[9] L☉
Temperature	9,623[9] K
Rotational velocity (v sin i)	30[10] km/s
Age	43.4±7.8[8] Myr
Other designations
Oculus, π Cap, 10 Cap, ADS 13860, BD−18°5685, HD 194636, HIP 100881, HR 7814, SAO 163592, WDS J20273-1813AB[11]
Database references
SIMBAD	data

In Chinese, 牛宿 (Niú Su), meaning Ox (asterism), refers to an asterism consisting of π Capricorni, β Capricorni, α² Capricorni, ξ² Capricorni, ο Capricorni and ρ Capricorni.^[13] Consequently, the Chinese name for π Capricorni itself is 牛宿四 (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.^[8] The star is radiating 238 times the Sun's luminosity from its photosphere at an effective temperature of 9,623 K.^[9] The third member, component B, is an eighth magnitude star at an angular separation of 3.4″ from the primary.^[15]