Nu Geminorum
Star system in the constellation Gemini
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Nu Geminorum, Latinized from ν Geminorum, is a triple[5] star system in the constellation Gemini. It has an apparent visual magnitude of 4.16,[2] 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,[1] 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.[9][10]
  | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Gemini |
| Right ascension | 06h 28m 57.78613s[1] |
| Declination | +20° 12â² 43.6856â³[1] |
| Apparent magnitude (V) | 4.16[2] |
| Characteristics | |
| Spectral type | B6 III + B8 III[3] |
| UâB color index | â0.47[2] |
| BâV color index | â0.13[2] |
| Astrometry | |
| Radial velocity (Rv) | +39.4[4] km/s |
| Proper motion (μ) | RA: â6.82[1] mas/yr Dec.: â13.10[1] mas/yr |
| Parallax (Ï) | 5.99±0.28 mas[1] |
| Distance | 540 ± 30 ly (167 ± 8 pc) |
| Absolute magnitude (MV) | â2.2 + â1.2[3] |
| Orbit[5] | |
| 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 (Ï) (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[5] | |
| 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 (Ï) (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[5] Mâ |
| Luminosity | 1,380[6] Lâ |
| Temperature | 14,100[6] K |
| Rotational velocity (v sin i) | 160[7] km/s |
| ν Gem Ab | |
| Mass | 3.28[5] Mâ |
| ν Gem B | |
| Mass | 3.33[5] Mâ |
| Other designations | |
| ν Gem, 18 Geminorum, BD+20°1441, FK5 1173, HD 45542, HIP 30883, HR 2343, SAO 78423, WDS 06290+2013[8] | |
| Database references | |
| SIMBAD | data |
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.[5] 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.[5] 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.[5]
ν Gem together with γ Gem (Alhena), η Gem (Propus), μ Gem (Tejat), and ξ Gem (Alzirr) formed the Arabic asterism Al NuḥÄtai, the Camel's Hump; ν Gem being the only one of these stars that is otherwise unnamed.[11] 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.[12]
On 15 August 2028, it will be occulted by Venus over Southern Africa and Madagascar.[13]:â165â