Struve 1835: A Double Star of Brilliant White and Deep Yellow in Boötes

Struve 1835 is an attractive double star in the northern constellation of Boötes. It’s best viewed during the springtime.

Boötes is home to a fair share of pretty double stars, including the white and yellow Struve 1835. Both of Struve 1835’s stars are within the +5-6 magnitude range. This makes it an excellent choice for suburban stargazers seeking a bright and captivating target. Additionally, the 6 arcseconds of space between the stars provides a fun and achievable challenge for those attempting to distinguish the two stars.

The brighter primary star has a spectral type known as A0V, which is classified as an A-type main-sequence star. Vega is a comparable star. And like Vega, Steuve 1835’s primary reminds me of a white diamond with brilliant “fire” or sparkle. On the other hand, the slightly dimmer secondary star is an F-type main sequence star, leaning toward yellow.¹

What’s so interesting is that both stars are technically white in color. However, much like my observation of nearby Kappa Boötis (Asellus Tertius), this double star has various reports of colors. For example, Bob Argyle writes on the Webb Deep-Sky Society website that “Hartung makes the colours white and deep yellow, Sissy Haas has goldish-white and powder blue whilst W. S. Franks in 1916 made them white and lilac.”²

Historically speaking, the astronomer William Herschel first recorded this double on an early morning Christmas Eve of 1781.

My Observations

After a long but momentous day of bringing my daughter home from her first year at college, I’ve decided to spend some time under some warm clear skies of May. This double is great. The top star in my eyepiece must be the primary, shining as a brilliant white. The slightly dimmer bottom star appears yellowish in color. I have used the 8mm eyepiece to separate them well, though I could still split them with the 12mm without trouble.

Key Stats

Constellation	Boötes
Best Viewing	Spring
Visual Magnitude	+5.0, +6.8
Separation	6.1″
Position Angle	195°
Spectral Class	Primary=A0V, Sec=F2V
Absolute Visual Magnitude	+.93
Distance from Earth	215 ly
Milky Way Location	Orion Spur
My Viewing Grade	A-
Designations	STF 1835, SAO 120426, HD 126129, HIP 70327, HR 5386

Sources and Notes

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

²Argyle, B. (2023, May). Double star of the month in Bootes. Webb Deep-Sky Society: Double Star of the Month in Bootes. Retrieved May 6, 2023, from https://www.webbdeepsky.com/double-stars/constellation/Bootes

Sketch by Wayne McGraw