Nu Andromedae
Binary star in the constellation Andromeda
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Nu Andromedae is a binary star system in the constellation Andromeda. Its Bayer designation is Latinized from ν Andromedae, and abbreviated Nu And or ν And, respectively. The system has an apparent visual magnitude of 4.5,[2] which is bright enough to be seen with the naked eye. Based on parallax measurements, it is located at a distance of approximately 560 light-years (170 parsecs) from Earth.[1] The pair are drifting closer with a heliocentric radial velocity of –24 km/s.[6] Situated just over a degree to the west of this star is the Andromeda Galaxy.[12]
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| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Andromeda |
| Right ascension | 00h 49m 48.846s[1] |
| Declination | +41° 04′ 44.08″[1] |
| Apparent magnitude (V) | 4.522[2] |
| Characteristics | |
| Spectral type | B4/5 V[3][4] + F8 V[5] |
| U−B color index | –0.573[2] |
| B−V color index | –0.136[2] |
| Astrometry | |
| Radial velocity (Rv) | –23.9[6] km/s |
| Proper motion (μ) | RA: +21.711 mas/yr[1] Dec.: –18.694 mas/yr[1] |
| Parallax (π) | 5.7868±0.1857 mas[1] |
| Distance | 560 ± 20 ly (173 ± 6 pc) |
| Absolute magnitude (MV) | −1.85[7] |
| Orbit[5] | |
| Period (P) | 4.2827 d |
| Eccentricity (e) | 0.03 |
| Longitude of the node (Ω) | 25.° |
| Periastron epoch (T) | 18,155.67 |
| Semi-amplitude (K1) (primary) | 71.7 km/s |
| Semi-amplitude (K2) (secondary) | 101.9 km/s |
| Details | |
| ν And A | |
| Mass | 5.9±0.2[3] M☉ |
| Radius | 3.4[8] R☉ |
| Luminosity | 1,104[7] L☉ |
| Surface gravity (log g) | 4.12±0.43[9] cgs |
| Temperature | 14,851±396[9] K |
| Metallicity [Fe/H] | +0.14±0.17[9] dex |
| Rotational velocity (v sin i) | 20[10] km/s |
| Age | 63.1±17.9[3] Myr |
| Other designations | |
| ν Andromedae, ν And, Nu And, 35 Andromedae, 35 And, BD+40 171, FK5 1021, HD 4727, HIP 3881, HR 226, SAO 36699, PPM 43365[11] | |
| Database references | |
| SIMBAD | data |
Nu Andromedae is close spectroscopic binary[3] system with a period of 4.2828 days and a nearly circular orbit.[5] The primary component is a B-type main sequence star with a stellar classification of B5 V.[3] The fainter secondary has a classification of F8 V,[5] which makes it an F-type main sequence star. The pair is about 63 million years old.[3]
The pair have a peculiar velocity of 22.16±0.87 km/s relative to neighboring stars, which doesn't qualify it to be a runaway star system but does suggest it escaped its star cluster of origin. The trajectory indicates it may have left the NGC 6405 cluster some 25 million years ago.[13]
Naming
In Chinese, 奎宿 (Kuí Sù), meaning Legs (asterism), refers to an asterism consisting of ν Andromedae, η Andromedae, 65 Piscium, ζ Andromedae, ε Andromedae, δ Andromedae, π Andromedae, μ Andromedae, β Andromedae, σ Piscium, τ Piscium, 91 Piscium, υ Piscium, φ Piscium, χ Piscium and ψ1 Piscium. Consequently, the Chinese name for ν Andromedae itself is 奎宿七 (Kuí Sù qī, English: the Seventh Star of Legs.)[14]