Now, three Albireos for ASPB!

Sam Storch

Much has been said in our club about the blue and gold double star Albireo, the beautiful eye of Cygnus, the Swan. We frequently rely on the showy color contrast, separation, and brightness of Albireo (Beta Cygni) as a sure crowd pleaser at star parties.

Eventually many of us discovered that another star, Almach (Gamma Andromedae) is also a satisfying double star for our telescopes. During the late evenings of summer, all through the fall, and perhaps into the early evenings of winter itʼs actually possible to enjoy both of these beauties together on the same sky. Both stars please both the new observer and the experienced hobbyist. Each is easily separated, shows a similar and dramatic color contrast, and is easy to locate even in badly light-polluted skies.

Now, Iʼve come to enjoy yet another star of similarly pleasing characteristics. Last year, our own Jim Kimball brought this star to my attention. This star is at its best during the wonderfully cold and clear nights of winter, or what passes for winter in south Florida.

To capture our new prize, we begin at the bright star Sirius (the Dog Star), and then move southward to the triangle of fairly bright stars forming the hind legs of the dog. These are the stars named Wesen, Adhara, and Aludra. Looking just east of the triangle is an interesting star with a similar color contrast to that of Albireo or Almach. Perhaps you will agree that it has an even more intense reddish-yellow star to be compared with its blueish companion.

Finding the star is easy on any night whenever you have a good view of the triangle marking the hind legs of the dog. Draw a line on the sky from Adhara to Wesen (yes, youʼll have to learn which is which!) and extend that line for the same distance again. Our target star joins the three bright stars you used to make a nice "cross" shape on the sky. In your finder, a warm color might be a hint that youʼve found the right star. This double star has several designations, including HR 2764, Herschel 3945, HIP 35210 and 35213, or even TYC6537-3290-1, depending on how your favorite star atlas or software labels this beauty. The star is at approximately RA 7h 17m and south DEC -23°19ʼ.

This double star was discovered in the 19th century by William Herschelʼs son John Herschel. This was, alas, a little "before my time." According to astronomer Dr. James Kaler, this star is sometimes known as the "Albireo of Winter." Interestingly, the late George Lovi, a renowned expert in celestial cartography, used that same designation for Almach, in Andromeda! Thatʼs a good justification for the modern numerical systems for identifying stars without ambiguity.

Each of our "three Albireos" is dramatic, easy to enjoy even in a small telescope, and well worth the time to locate and show to people who are new to using a telescope. The other night, I enjoyed an impressive view of the double star at only 37X viewing with a 70-mm TeleVue Ranger refractor. In fact, the star is so easy to locate that you can just put a red dot finder or a Tel-Rad at the approximate location on the sky and you will be rewarded promptly. Wasnʼt it nice of the "double star gods" to put such a nice star at exactly the right spot?

A TABLE OF THREE "ALBIREOS"

STARCONSTELLATIONSEASON TO ENJOYSEPARATIONCOLORS
AlbireoCygnussummer through fall35"yellow and blue
AlmachAndromedafall into winter9.5"orange and blue
H3945Canis Majorwinter27"orange-yellow and blue

The diagrams which follow were created using Starry Night Pro software, and show the part of the sky youʼll be looking at while outdoors. The first diagram shows you nearly all of Canis Major. You can see the triangle of three stars (Wesen, Adhara, and Aludra) marking the hind legs of the dog as well as the position marked for the star that we seek.

In the second image, the blue lines are the traditional constellation lines drawn in, while the red line in the second diagram gets you to the target star. The blue line extending up and out of the top of that image heads on to Sirius. The sky portrayed in this image is roughly 10° wide.

The area of the sky in and around Canis Major has quite a few open star clusters and is a pleasing area for further exploration before you head back inside the house. The next time you instinctively head for the always-spectacular Orion nebula or for the fine open cluster M-41 just south of Sirius, enjoy a look at a fine double star that will remind you of Albireo or Almach! You wonʼt be disappointed.

The constellation Canis Major, showing the stars named in the text.  

The constellation Canis Major, showing the stars named in the text.
 

This and the following diagram were created by the author using Starry Night Pro software.

The "legs" of the dog, and the path to the double star.

The "legs" of the dog, and the path to the double star.