A Selection of Double Stars in Andromeda
November 2008 :
Andromeda is a wonderful constellation to explore on a chilly November evening. We can spend many an hour at the telescope admiring the grandeur of the Andromeda Galaxy (M31) or the delicate beauty of the planetary nebula NGC7662 (the “Blue Snowball”). Andromeda is also home to a fine collection of double stars. Here are eight of the best. Data on magnitudes and separation were taken from the Washington Double Star Catalog.
Struve 3050 And mags 6.5 and 6.7, sep 2.0”, P.A. 334o (2004) We start out with a pair that will challenge a 3-inch scope, but should be easy in a 4-inch or larger if the seeing is good. Use 150-200X. Both components have been described as yellowish.
Groombridge 34 And mags 8.1 and 11.0, sep 34.8”, P.A. 65o (2004) Grb 34 may not be a visually spectacular pair, but the interest factor makes it worth a look. A red dwarf binary with an orbital period estimated at 2600 years, it’s one of the nearest binary stars to our solar system (D = 11.7 LY). Grb 34 is 1/4o north and slightly east of 26 Andromedae.
Pi And (H V 17) mags 4.3 and 7.1, sep 36.0”, P.A. 173o (2003) This wide, unequal pair is easily split with small scopes. Its colors have been described as white and blue. What do you see?
36 And (Struve 73) mags 6.1 and 6.5, sep1.0”, P.A. 314o (2004) For moderate-sized scopes only, this tight binary pair (Period = 165 years) requires a 6 to 8 inch telescope, optimum seeing conditions, and a magnification between 200-300X. Are you up to the challenge?
Struve 79 And mags 6.0 and 6.8, sep 7.8”, P.A. 193o (2004) Countless thousands of backyard astronomers have gazed at the Andromeda Galaxy. But how many have taken the time to look 4o to the northeast for this lovely gem? Both are white and stand out well at 100X.
56 And (Struve I 4) mags 5.8 and 6.1, sep 200.5”, P.A. 299o (2001) Still reluctant to engage in double star observing? Next time you’re checking out the open cluster NGC 752, look for a wide pair of stars immediately southwest. This is the optical pair 56 Andromedae. It’s better suited for binoculars, but if you use a telescope, look about a degree west and slightly north for the delicate little pair Struve 179 (mags 7.6 and 8.1, sep 3.8”, P.A. 314o).
Gamma And (Struve 205) Almach mags 2.3 and 5.0, sep 9.7”, P.A. 63o (2004) Now for the showpiece. This magnificent pair sports rich golden yellow and sapphire blue hues – a definite rival for the celebrated Albireo. Almach is a wonderful target for star parties, especially on moonlit nights when clusters and galaxies are hard to see.
59 And (Struve 222) mags 6.1 and 6.7 , sep 16.5”, P.A. 36o (2003) To capture this lovely pure-white duo, look 4o south and slightly east of Almach. A magnification of 50X will do the trick.
