Struve 872: A Mystical Pair of Yellow and Lilac

Struve 872 (STF 872) is a double star in the Auriga constellation, best viewed on winter nights.

At first glance, one may think STF 872 is a tight, white pair of average stars floating in Auriga. But stare at these points of light for a little longer, and a lighter yellow color for the primary star and a lilac color for the secondary emerge—at least that was my experience (see my description below).

On record, the primary star is a yellow-white subgiant classified as an F4IV spectral type, and it’s nearly one and a half times larger than our sun. The secondary star with its pink/lilac color lies a little more than 11 arcseconds away. Most likely, this pair is simply an optical double and not a true binary.

My Observations

What a mystical pair of stars! Professional observations record the primary as being yellow and the secondary as lilac. At first glance, I first thought STF 872 was simply two grey-white stars. But as I let the light seep into my eyes for a few seconds, it seemed as if the stars’ colors morphed mysteriously into pink and yellow. My eyes were playing games with me. I’ll have to visit this pair again in the future to see what colors jump out.

Key Stats

Constellation	Auriga
Best Viewing	Winter
Visual Magnitude	+6.8 | +7.4
Separation	11.3″ | 608 AU
Position Angle	215°
Spectral Class	A=F4IV, B=?
Absolute Visual Magnitude	+3.9
Distance from Earth	175 ly
Milky Way Location	Orion Spur
My Viewing Grade	B
Designations	SAO 58905, HR2217, STF 872

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