Struve 2679: A Quaint Triangle Star System in Delphinus

Delphinus the Dolphin is a relatively modest constellation, but its distinctive shape makes it easily identifiable for those familiar with the night sky. The sky dolphin boasts a variety of nice celestial objects, including Struve 2679, a multiple-star system that is visible during late summer and early autumn nights.

Struve 2679 appears as a tiny triangle made of a bright primary “A” star (magnitude +7.8), a dimmer “B” star (magnitude +9.7), and then a dim “C” star (magnitude +12.3). The two brighter stars, “A” and “B” of the triangle, are separated by 24.4 arc seconds.

John Nanson discusses more about Struve 2679 on the Star Splitters website—a worthy read for sure! As Nanson points out, Friedrich Georg Wilhelm von Struve first recorded stars “A” and “B” as a double star system. Years later, in 1895, the third star “C” was added to the star system.¹

My Observations

As I start to look at this, I only see the primary and secondary star. The primary is a bright white with the secondary placed to the “right” of it in my eyepiece. The third “C” star has slowly started to appear below these two, thus making this quaint little triangle to enjoy.

Key Stats

Constellation	Delphinus
Best Viewing	Autumn
Visual Magnitude	+7.8, +9.7, +12.3
Separation	24.4″
Position Angle	77°
Spectral Class	A=A2, B=F0
Absolute Visual Magnitude	+.90
Distance from Earth	800 ly
Milky Way Location	Orion Spur
My Viewing Grade	B
Designations	HIP 100638, SAO 106068, STF 2679

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.

¹ Nanson, J. (2013, October 4). A complication of stars in Delphinus, part Two: BU 363 and Σ 2679. Star-Splitters. https://bestdoubles.wordpress.com/2013/09/17/a-complication-of-stars-in-delphinus-part-two-bu-363-and-%CF%83-2679/

Sketch by Wayne McGraw