A Selection of Double Stars in Draco
July 2008 :
A hazy summer evening may prevent you from observing nebulae and galaxies, but it could afford ideal seeing conditions for high power targets like double stars. Draco is a sprawling north circumpolar constellation teeming with double and multiple stars. Using a modest 3- inch f/10 Newtonian reflector, I have observed and sketched over sixty stellar partnerships, including the half dozen presented here. All are found in and around the four-star group that outlines the Dragon’s head. (Data from the Washington Double Star Catalog - WDS)
16,17 Draconis (StruveI 30) : magnitudes 5.4 and 5.5, separation 89.8”, Position Angle 196° (2003) This pretty binocular pair has a surprise for anyone who observes it telescopically. It’s actually a triple star! Carefully examine 17 Draconis with high power (120x, or more), and you’ll see that it’s a close double (Struve 2078; mags 5.4 and 6.4, sep 3.0”, P.A. 107° (2003).
? (mu) (Struve 2130) : mags 5.7 and 5.7, sep 2.3”, P.A. 14° (2004) Binary (Period = 482 years) Beautiful twin pair that requires 100x or better for a clean split. A showpiece!
Struve 2138 : mags 9.0 and 9.4, sep 22.7”, P.A. 133° (2004) To find this faint, but pretty pair, point your telescope about one degree east of mu Draconis.
Struve 2180 : mags 8.0 and 8.1, sep 3.0”, P.A. 260° (2000) Like Struve 2138, this is a rarelyobserved double that deserves attention. Located about 1.5 degrees south of beta Draconis, Struve 2180 resolves best when viewed with a magnification of 100x or more.
? (nu) (StruveI 35) : mags 4.9 and 4.9, sep 63.4”, P. A. 311° (2003) Faintest of the four stars in the Head of Draco, nu is a noble sight in a low power telescope. 30-60x gives the most dramatic view of these identical white stars.
Struve 2278 : mags 7.8 and 8.1, sep 35.9”, P.A. 28° (2004) A faint triple, as the secondary has a close partner (mag 8.5, sep 6.0”, P.A. 146° (2004).
