Lambda Andromedae
Lambda Andromedae, Latinized from λ Andromedae, is the Bayer designation for a binary star system in the northern constellation of Andromeda. At an estimated distance of approximately from Earth, it has an apparent visual magnitude of +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. Lambda Andromedae is a single-lined spectroscopic binary with an orbital period of 20.5212 days. The spectrum of the primary matches a stellar classification of G8 III-IV, suggesting that it is an  evolved star that lies part way between the subgiant and giant stages. The mass of this star is similar to the Sun, but it has expanded to around seven times the Sun's radius. It is radiating over 28 times the luminosity of the Sun from its outer envelope at an effective temperature of 4,800 K, giving it the characteristic yellow hue of a G-type star. This is an RS Canum Venaticorum variable and its brightness varies by 0.225 magnitudes, reaching a maximum of 3.70, with a period of 54.2 days. The companion is a low-mass star with  a mass of . Such variability is theorized to occur because of tidal friction, which results in chromospheric activity. However, the orbit of this system is nearly circular, so the cause of this system's variability remains uncertain. The X-ray luminosity of this star, as measured by the ROSAT satellite, is . A magnetic field with an average strength of has been detected on this star, which is stronger than the field on the Sun. Naming. In Chinese, (), meaning "Flying Serpent", refers to an asterism consisting of λ Andromedae, α Lacertae, 4 Lacertae, π Cygni, π Cygni, HD 206267, ε Cephei , β Lacertae, σ Cassiopeiae, ρ Cassiopeiae, τ Cassiopeiae, AR Cassiopeiae, 9 Lacertae, 3 Andromedae, 7 Andromedae, 8 Andromedae, κ Andromedae, ι Andromedae, and ψ Andromedae. Consequently, the Chinese name for λ Andromedae itself is (, ).