Lambda Andromedae
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Andromeda |
| Right ascension | 23h 37m 33.84278s |
| Declination | +46° 27′ 29.3447″ |
| Apparent magnitude (V) | 3.65 - 4.05 |
| Characteristics | |
| Evolutionary stage | subgiant |
| Spectral type | G8 IV |
| U−B color index | +0.688 |
| B−V color index | +0.996 |
| Variable type | RS CVn |
| Astrometry | |
| Radial velocity (Rv) | +6.8 km/s |
| Proper motion (μ) | RA: 159.606(101) mas/yr Dec.: −421.822(97) mas/yr |
| Parallax (π) | 38.5736±0.1179 mas |
| Distance | 84.6 ± 0.3 ly (25.92 ± 0.08 pc) |
| Absolute magnitude (MV) | 1.91 |
| Orbit | |
| Primary | A |
| Companion | B |
| Period (P) | 20.520394(41) days |
| Semi-major axis (a) | ≥(1.8536±0.0021)×106 km |
| Eccentricity (e) | 0.0607±0.0012 |
| Periastron epoch (T) | 2459696.372±0.056 BJD |
| Argument of periastron (ω) (primary) | 336.8±1.0° |
| Semi-amplitude (K1) (primary) | 6.5815±0.0076 km/s |
| Details | |
| A | |
| Mass | 1.47±0.44 M☉ |
| Radius | 7.787±0.053 R☉ |
| Luminosity | 28.8 L☉ |
| Surface gravity (log g) | 2.75±0.25 cgs |
| Temperature | 4,633 K |
| Metallicity [Fe/H] | −0.56 dex |
| Rotation | 54.41±0.30 days |
| Rotational velocity (v sin i) | 7.3 km/s |
| B | |
| Mass | 0.086–0.115 M☉ |
| Other designations | |
| Udkadua, λ And, 16 Andromedae, BD+45°4283, FK5 890, GJ 9832, HD 222107, HIP 116584, HR 8961, SAO 53204, PPM 64456, LTT 16964, NLTT 57442 | |
| Database references | |
| SIMBAD | data |
Lambda Andromedae, Latinized from λ Andromedae, also named Udkadua, is a binary star system in the northern constellation of Andromeda. At an estimated distance of approximately 84.6 light-years (25.9 parsecs) from Earth, it has an apparent visual magnitude of around +3.8. This is bright enough to be seen with the naked eye. The system is drifting further away from the Sun with a radial velocity of +6.8 km/s.