Struve 698: A Colorful Pair of Orange and Blue

Struve 698 is a double star in the Auriga constellation, best viewed on winter nights.

This pair has several great attributes: it’s colorful, bright, and fairly wide apart. The 6th magnitude star (spectral type K1pIII-IV) is almost 12 times the diameter of our sun. Meanwhile, the fainter secondary and bluish star is a good 31 arcseconds away, making it easy for backyard observers with smaller scopes to separate the two stars.

My Observations

On this hazy cold winter night, with bands of high clouds passing overhead, I’m delighted that my scope is able to break through to see a beautiful pair like this one. The primary star shines like a warm incandescent lightbulb with an orange hue, while the nearby secondary star cools the scene with its light blue light. A great pair to visit on cold winter nights!

Key Stats

Constellation	Auriga
Best Viewing	Winter
Visual Magnitude	+6.6 | +8.3
Separation	31.4″ | 3915 AU
Position Angle	348°
Spectral Class	A=K1pIII-IV, B=?
Absolute Visual Magnitude	+1.0
Distance from Earth	170 ly
Milky Way Location	Orion Spur
My Viewing Grade	A-
Designations	HR 1779, STF 698, SAO 57999

Sources and Notes

Banner illustration was created by the European Southern Observatory (ESO) and is under the Creative Commons Attribution 4.0 International License. Per ESO agreement: Here is the original image on the ESO website.

Sketch by Wayne McGraw