Thursday, April 15, 2010

Seeing Double

I must disclose that, although I like a bright double star with a nice color combination as much as the next amateur, I don’t make a habit of observing doubles. I don’t own a double-star book or atlas. I don’t work my way through double-star checklists. And unless there’s enough separation to drive a Mack truck (or the starship Enterprise) between them, I don’t get particularly excited about the challenge of “splitting” doubles with my binoculars or telescope.

Oddly, my Mrs. Magoo eyes find it easier to discern structure in galaxies than to bring stars into sharp enough focus to reveal dim companions lurking nearby or to detect that One is really Two.

But I recognize that double stars have much to offer both beginning and seasoned observers, and that there are many avid and accomplished double-star hunters out there. One of these is Dee Friesen, a New Mexico amateur.

Dee is a Vietnam veteran and a retired commercial airline pilot. “Retired” being a relative term. Dee is very active with the local children’s science center and with public astronomy outreach in the area. He recently stepped down from a two-year stint as president of the local astronomy club. In addition, he teaches college-level astronomy and aviation. In his spare time, he and his wife travel extensively.

Dee sampling a local libation in New Zealand
Image by Ruth Friesen

I caught up with Dee recently to probe his fascination with double stars.

Whassup: So, Dee, why double stars?

Dee: I can barely make out “faint fuzzies” with the size telescope I have. I can’t discern very many features, so I’m not seeing much—other than, well, it’s there.

I like double stars because I like the theory of stars and the science of them. When I look at double stars, I can see color and magnitude. They tell me what they’re made of and what their temperature is, maybe even their relative size and distance. I feel close to what I’m seeing.

Whassup: How would you compare double stars to other targets?

Dee: From a practical standpoint, I can observe double stars on nights when the seeing and transparency aren’t good enough to see other things. I also find them easier to find. Plus, there’s beauty, there’s much more variation in color intensity, their separation, the comparative magnitude. You get interesting combinations.

I kind of enjoy not observing the obvious or popular things like the dim dark fuzzies. I like to be different!

Whassup: What else would you like us to know about doubles?

Dee: There was a time when double stars were looked at a lot. Go back 100 years, and they were looked at a lot by both professionals and amateurs.

I like observing double stars because I don’t need the biggest fanciest equipment, I can do it in many places, and I don’t have to have the best sky conditions to see them.

Here are Dee’s picks for easy double stars for this time of year. If you want to give double stars a try, these are good targets for beginners. Happy hunting!

Polaris, the North Star, in the constellation Ursa Minor the Little Bear.
Telescope object. The position of the companion star rotates 15 degrees each hour, making it an excellent object to observe to detect the rotation of the Earth.

Mizar and Alcor, in the constellation Ursa Major the Big Bear.
Naked-eye object. The famous double in the handle of the Big Dipper. Also known as the Horse and Rider. Alcor is the dim companion to bright Mizar. If you can see both naked eye, you have good eyesight!

The Trapezium, in the constellation Orion the Hunter.
Telescope object. This is actually a quadruple star group in the Great Orion Nebula, the center “star” in Orion’s Sword. The four young stars, arranged in a diamond pattern, were born about a million years ago from the gas and dust in the nebula.

, in the constellation Canis Major the Big Dog.
Telescope object. The stars are yellow and blue. Known as the "Winter Albireo" (after the famous blue & gold double star Albireo in Cygnus the Swan – summer object).

, in the constellation Leo the Lion.
Naked-eye object. An easy-to-find double in the Sickle asterism.