Nu Geminorum
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Gemini |
| Right ascension | 06h 28m 57.78613s |
| Declination | +20° 12′ 43.6856″ |
| Apparent magnitude (V) | 4.16 |
| Characteristics | |
| Spectral type | B6 III + B8 III |
| U−B color index | −0.47 |
| B−V color index | −0.13 |
| Astrometry | |
| Radial velocity (Rv) | +39.4 km/s |
| Proper motion (μ) | RA: −6.82 mas/yr Dec.: −13.10 mas/yr |
| Parallax (π) | 5.99±0.28 mas |
| Distance | 540 ± 30 ly (167 ± 8 pc) |
| Absolute magnitude (MV) | −2.2 + −1.2 |
| Orbit | |
| Primary | ν Gem Aa |
| Name | ν Gem Ab |
| Period (P) | 53.7722 ± 0.0008 d |
| Semi-major axis (a) | 2.82 ± 0.02 mas |
| Eccentricity (e) | 0.056 ± 0.003 |
| Inclination (i) | 0.98 ± 0.03° |
| Longitude of the node (Ω) | 78.9 ± 0.2° |
| Periastron epoch (T) | MJD 51011.8 ± 0.1 |
| Argument of periastron (ω) (secondary) | 6.7 ± 2.0° |
| Semi-amplitude (K1) (primary) | 51.6 ± 0.6 km/s |
| Semi-amplitude (K2) (secondary) | 52.5 ± 1.1 km/s |
| Orbit | |
| Primary | ν Gem A |
| Name | ν Gem B |
| Period (P) | 6977.3 ± 6.1 |
| Semi-major axis (a) | 82.8 ± 1.3 mas |
| Eccentricity (e) | 0.241 ± 0.002 |
| Inclination (i) | 75.9 ± 0.2° |
| Longitude of the node (Ω) | 121.0 ± 0.1° |
| Periastron epoch (T) | MJD 48810.3 ± 13.0 |
| Argument of periastron (ω) (secondary) | 226.9 ± 0.4° |
| Semi-amplitude (K1) (primary) | 8.0 ± 0.1 km/s |
| Semi-amplitude (K2) (secondary) | 15.9 ± 0.1 km/s |
| Details | |
| ν Gem Aa | |
| Mass | 3.34 M☉ |
| Luminosity | 1,380 L☉ |
| Temperature | 14,100 K |
| Rotational velocity (v sin i) | 160 km/s |
| ν Gem Ab | |
| Mass | 3.28 M☉ |
| ν Gem B | |
| Mass | 3.33 M☉ |
| Other designations | |
| ν Gem, 18 Geminorum, BD+20°1441, FK5 1173, HD 45542, HIP 30883, HR 2343, SAO 78423, WDS 06290+2013 | |
| Database references | |
| SIMBAD | data |
Nu Geminorum, Latinized from ν Geminorum, is a triple star system in the constellation Gemini. It has an apparent visual magnitude of 4.16, which is bright enough to be visible to the naked eye on a dark night. Based upon an annual parallax shift of 5.99 mas, it is located at a distance of roughly 540 light years from the Sun. The position of this system near the ecliptic means it is subject to lunar occultations.
The inner components of this multiple star system have an orbital period of about 54 days and a nearly circular orbit with an eccentricity of 0.056. There is some uncertainty in the spectral type, with classifications ranging from a main sequence star to a giant. Orbiting the inner pair is a classical Be star, with an orbital period of 19.1 years and an eccentricity of 0.24. The two orbits are co-directional and roughly coplanar. The system is overall dynamically stable, and shows no signs of Kozai-Lidov cycles. The outer Be star appears to be single.
ν Gem together with γ Gem (Alhena), η Gem (Propus), μ Gem (Tejat), and ξ Gem (Alzirr) formed the Arabic asterism Al Nuḥātai, the Camel's Hump; ν Gem being the only one of these stars that is otherwise unnamed. Based on this, the catalogue of stars in the Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars listed ν Gem with the name Nucatai.
On 15 August 2028, it will be occulted by Venus over Southern Africa and Madagascar.