|Epsilon Lyrae, the Double Double|
Double stars are interesting to people for a number of reasons. Some like the challenge of splitting close pairs with the smallest instrument possible. Others like to measure the characteristics, such as separation, position angle and magnitudes. But what really delights most people is a pair that exhibits a striking color combination. Some of the more popular pairs include Alberio (gold/sapphire), gamma Andromedae (gold/blue), xi Bootis (yellow/red) and alpha Herculis (red/green). I don't want to get into a debate about the perceived colors of these pairs. Your mileage may vary.
My favorite double has them all beat. It is a very colorful pair, with a blue-white primary and a deep red secondary. But the best part is this. It looks different every time you look at it, because the deep red secondary is a variable star! That's right, my favorite double star is also a variable.
You knew that was coming, right?
Okay, okay, I'll end the suspense. My favorite double is the Mira variable T Draconis.
|T Draconis resides just north of the head of the dragon|
The faint stars in the comparison star sequence for T Draconis