Zeta Andromedae


Zeta Andromedae is a star system in the constellation Andromeda. It is approximately 189 light years from Earth.
Zeta Andromedae is a spectroscopic binary whose primary is classified as an orange K-type giant with a mean apparent magnitude of +4.08. In addition to brightness variation due to the ellipsoidal shape of the giant primary star, the system is also an RS Canum Venaticorum type variable star. Its brightness varies from magnitude +3.92 to +4.14 with a period of 17.77 days, and its spectrum shows strong and variable Ca II H and K lines. The orbital period of the binary is 17.77 days.

Location

This star's location in the constellation Andromeda can be seen in the following diagram:

Direct imaging

The primary component of this binary system, Zeta Andromedae Aa, is one of the few stars who has been imaged directly using Doppler imaging and long-baseline infrared interferometry. With direct imaging we can recover additional information about this star.
ParameterValue
Oblateness1.060 ± 0.011
Polar radius15.0 ± 0.8 Solar radius|
Axis Inclination70.0 ± 2.8 °
Pole angle126 ± 1.9 °

Direct imaging also allowed observation of starspots,, on this star, and their asymmetric distribution showed that the magnetic field of the star is generated by a mechanism different from the solar dynamo. A Sun-like differential rotation of the star was observed instead.

Visual companions

The WDS lists more than one visual companion to the eclipsing binary. B has common proper motion with A. C is probably only a line-of-sight companion that has no physical association. The parallax of the D component has been measured by Gaia and the distance of this star is much different.

Naming

In Chinese, 奎宿, meaning Legs , refers to an asterism consisting of ζ Andromedae, η Andromedae, 65 Piscium, ε Andromedae, δ Andromedae, π Andromedae, ν 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 ζ Andromedae itself is 奎宿二