title: Zeta Sagittae
text: # Zeta Sagittae
  
  Zeta Sagittae (ζ Sagittae) is triple star system in the northern constellation of Sagitta. It is visible to the naked eye, having a combined apparent visual magnitude of +5.00. Based upon an annual parallax shift of 12.79 mas, the distance to this star is approximately 260 light years.
  
  The inner pair is a visual binary system consisting of two A-type main-sequence stars with an orbital period of 23.2 years (8,487.9 d), a semimajor axis of 0.136 arc seconds, and an eccentricity of 0.79. The primary, component A, has a visual magnitude of 5.64 with a stellar classification of A3 Vnn, where the 'nn' suffix indicates "nebulous" lines due to rotation. It is spinning rapidly with a projected rotational velocity of 240 km/s. This is giving the star an oblate shape with an equatorial bulge that is 14% larger than the polar radius.
  
  The secondary member, component B, is a magnitude 6.04 star, while the more distant component C is magnitude 9.01 and lies at an angular separation of 8.330 arc seconds from the other two.
  
  ## Naming
  
  In Chinese, 左旗 (Zuǒ Qí), meaning Left Flag, refers to an asterism consisting of ζ Sagittae, α Sagittae, β Sagittae, δ Sagittae, γ Sagittae, 13 Sagittae, 11 Sagittae, 14 Sagittae and ρ Aquilae. Consequently, the Chinese name for ζ Sagittae itself is 左旗四 (Zuǒ Qí sì, English: the Fourth Star of Left Flag.)
  
  