title: HD 130458
text: # HD 130458
  
  HD 130458 (HR 5520) is a double star in the southern circumpolar constellation of Apus. The pair has a combined apparent magnitude of 5.8, making it faintly visible to the naked eye under ideal conditions. Parallax measurements place the system 310-24 light years away and it is receding with a heliocentric radial velocity of 31.4 km/s.
  
  The primary is a red giant with a stellar classification of G7 IIIa. It was earlier classified as G8 IIb, indicating a bright giant.The dimmer component has a stellar classification of F9 IV, indicating that it is an F-type subgiant evolving onto the red giant branch. As of 2008 , the pair has an angular separation of 2.167″.
  
  At present the primary has 1.5 times the mass of the Sun but has expanded to 8.9 times its girth. It radiates at 55 times the luminosity of the Sun from its enlarged photosphere at an effective temperature 5,194 K, which gives it a yellow glow. Currently it spins leisurely with a projected rotational velocity of 3.6 km/s, common for giants. HD 130458A is believed to be on the horizontal branch.
  
  As for the secondary component, it has 1.4 times the mass of the Sun and an effective temperature of 6,601 K, giving a yellowish white hue.
  
  