41 Aurigae (Struve 845): A Lovely Pair with Debatable Color Differences in Auriga

41 Aurigae is a lovely double star located in the constellation Auriga, the Charioteer. Auriga is most prominent during winter evenings in the Northern Hemisphere. So put on your hat and gloves to catch this beauty first recorded by the famed astronomer William Herschel on November 6, 1783.¹

Before jumping into the specifics, I want to point out the inconsistent reports on the colors associated with this pair. Greg Stone provides a fitting summary on his Star Splitters website: “My notes say ‘blue and pale apricot’ – sounds delicious. However, Sissy Haas says it’s a ‘pair of yellow-white’ stars. Smyth has them as silvery white and pale violet. Oh boy! Yes, I was looking at the same star. No doubt. So I have no explanation for my radical color difference. Smyth’s colors seem closest to the spectrum classifications.”

I agree with Smyth’s assessment as I note below in my personal observation. For me, the primary star appears silvery white, while the slightly dimmer secondary appears blue, or slightly violet, in color. According to their actual star characteristics, the white primary star is a spectral type A1V, while the secondary star is a close A6V spectral type. Both are “white” stars, but their close proximity seems to create contrasting color reports.

My Observations

Auriga has to be one of my favorite constellations. It has a wealth of beautiful Messier objects (namely M 36, 37, and 38) along with a host of doubles and other wonderful sights. It’s no surprise then to me the pretty 41 Aurigae is part of the family.

41 Aurigae’s slightly brighter primary appears off-white, or as Smyth reports, “silvery white.” This star glitters against the dark background in my eyepiece. Beside it is a secondary star that appears blue at first glance. As I start at it, it does sparkle with a tinge of red for some reason, so perhaps that’s why Smyth reported it as violet? If I were forced to name the specific colors, I would describe this pair as silvery white and blue.

Regardless of the exact color, I find the pair to be lovely as they have slightly different colors, lie quite close, and shine brightly. The white against the blue seems so fitting for cold winter nights.

Key Stats

Constellation	Auriga
Best Viewing	Winter
Visual Magnitude	+6.2 | +6.9
Separation	7.5″
Position Angle	358°
Spectral Class	A1V & A6V
Milky Way Location	Orion Spur
My Viewing Grade	A
Designations	SAO 40924, HD 42126, HR 2175, 41 Aur,

Sources and Notes

Banner adapted from an illustration created by Pablo Budassi. The illustration is licensed under the Creative Commons Attribution-Share Alike 4.0 International license. Full details here.

¹ William Herschel’s double star catalog. (n.d.). https://www.handprint.com/ASTRO/Herschel_All.html

Sketch by Wayne McGraw