Nu Aquarii
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aquarius |
| Right ascension | 21h 09m 35.648s |
| Declination | −11° 22′ 18.09″ |
| Apparent magnitude (V) | 4.520 |
| Characteristics | |
| Spectral type | G8 III |
| U−B color index | +0.66 |
| B−V color index | +0.943 |
| Astrometry | |
| Radial velocity (Rv) | −11.23 km/s |
| Proper motion (μ) | RA: +93.613 mas/yr Dec.: −15.494 mas/yr |
| Parallax (π) | 20.0842±0.1137 mas |
| Distance | 162.4 ± 0.9 ly (49.8 ± 0.3 pc) |
| Absolute magnitude (MV) | +0.93 |
| Details | |
| Mass | 2.35 M☉ |
| Radius | 8 R☉ |
| Luminosity | 37 L☉ |
| Surface gravity (log g) | 2.88±0.09 cgs |
| Temperature | 4,920±5 K |
| Metallicity [Fe/H] | −0.06±0.04 dex |
| Rotational velocity (v sin i) | 2.8±0.3 km/s |
| Age | 708 Myr |
| Other designations | |
| ν Aquarii, ν Aqr, Nu Aqr, 13 Aquarii, BD−11 5538, HD 201381, HIP 104459, HR 8093, SAO 164182 | |
| Database references | |
| SIMBAD | data |
Nu Aquarii is a star in the equatorial constellation of Aquarius. The name is a Bayer designation that is Latinized from ν Aquarii, and abbreviated Nu Aqr or ν Aqr. With an apparent visual magnitude of 4.52, Nu Aquarii is faintly visible to the naked eye. Its distance from Earth, as determined from parallax measurements, is 162 light-years (50 parsecs). The star is drifting closer to the Sun with a radial velocity of −11 km/s.
At an estimated age of 708 million years, Nu Aquarii has exhausted the supply of hydrogen at its core and evolved into a giant star with a spectrum that matches a stellar classification of G8 III. It has double the mass of the Sun and has expanded to eight times the Sun's radius. Nu Aquarii is radiating 37 times the luminosity of the Sun from its photosphere at an effective temperature of 4,920 K. At this heat, the star is glowing with the yellowish hue of a G-type star.
Together with μ Aquarii, it is Albulaan /ˌælbjəˈlɑːn/, a name derived from the Arabic term al-bulaʽān (ألبولعان), meaning "the two swallowers". This star, along with ε Aqr (Albali) and μ Aqr (Albulaan), were al Bulaʽ (البلع)—the Swallower.
In Chinese, 天壘城 (Tiān Lěi Chéng), meaning Celestial Ramparts, refers to an asterism consisting of ν Aquarii, ξ Aquarii, 46 Capricorni, 47 Capricorni, λ Capricorni, 50 Capricorni, 18 Aquarii, 29 Capricorni, 9 Aquarii, 8 Aquarii, 14 Aquarii, 17 Aquarii and 19 Aquarii. Consequently, the Chinese name for ν Aquarii itself is 天壘城十 (Tiān Lěi Chéng shí, English: the Tenth Star of Celestial Ramparts).