Struve Σ 2470 and 2474: The Other Double Double

[Nightspore]

Struve 2470 and 2474 are an interesting pair of double stars in Lyra comprising of SAO 67867 and SAO 67870 as the northern pair. With SAO 67879 and SAO 67875 as the more southerly double. Because of their similarity to Epsilon Lyrae they are often referred to as the ‘Other Double Double’.

 

 

SAO 67867 is an eighth magnitude star around four hundred and eighty eight light years away. With a spectral type A0 it is just over eight times the luminosity of Sol.

 

 

The secondary (67870) is a blue-white main sequence star three times the diameter of the Sun and around thirteen hundred light years away.

 

 

SAO 67879 is a yellow main sequence star one hundred and seventy one light years away. It is over twice the Sun’s diameter. SAO 67875 is a yellow G5 star, one hundred and thirty nine light years distant. It outputs about eighty eight percent of the energy of Sol.

 

Mirror reversed (Cartes du Ciel)

 

This little collection of stars are an often overlooked foursome. The group can appear quite dramatic when first discovered as both pairs of stars are almost parallel. They are probably best observed around a 50-80x magnification. The Struve pair are not too difficult to find as they make a loose triangle with ᵦ Lyr (Sheliak) and ᵞ Lyr (Sulafat).

 

 

 

Screenshots by courtesy of Stellarium, Cartes du Ciel, Shotwell and Ksnip.