Bursting with Doubles

The constellation Boötes is pretty sparse when it comes to anything to observe. It contains only one globular cluster (NGC 5466), which by all accounts is a pretty poor example of the breed. Sky and Telescope's Pocket Sky Atlas lists only 5 galaxies within its boundaries, none of which are anything to write home about. Perhaps it is fitting that Bootes is home to the great Boötes Void, a 250 million light year diameter bubble of nothingness - no stars, no gas, no galaxies, and apparently no dark matter. Just nothing. (Obviously not a good target for observation!)

But what Boötes lacks in the splashier DSOs is more than made up for in its fine collection of double stars, several of which (such as Izar, a.k.a., Epsilon Boötes) routinely make the lists of "must see" doubles.

Struve 1835, and companions

But today I intend to focus on a lesser known example, Struve 1835. Located near the extreme southern edge of the constellation, almost due south of bright Arcturus and not far from the boundary with Virgo there lies an attractive chain of three stars, slightly curving to the northwest. The stars making up this asterism gradually increase in magnitude as you progress up the chain, making it lovelier still. The "bottom" star (HD 126271) has an apparent magnitude of 6.19. The middle star (HD 126200) shines at 5.95, while Struve 1835 has a combined magnitude of 5.12. All by itself, this beautiful trio is worth a glance or two.

Hmm... This 3-star asterism is currently unnamed. Let's see, we already have Brocchi's Cluster (the Coathanger), Herman's Cross, and Kemble's Cascade. Why not Prokop's Parade? (Alliteration is always a plus!)

But the real gem is that brightest star at the top. Pump up the magnification, and you'll split Struve 1835 into its component members. Descriptions vary enormously as to what colors different observers see. Some see no color at all, just two unevenly matched white stars. At least one observer has noted "2 yellow stars". But the most common description is of a bright blue primary with a dimmer secondary of uncertain hue, ranging from gray to purple.

I was unable to find an image of this star on the internet, but I did come across this very fine sketch (below).