Stargazers: Stars of a different color amaze
I've been gazing skyward now for more than five decades, and I'm still amazed at all we can see if we simply take the time to look up into a dark sky. Add to that a small telescope and the celestial sights become even more remarkable.
Take the colors of stars, for example. Most folks aren't even aware that stars display a variety of hues. Those appearing white are hotter than those that appear orange or red. Bluish stars are the hottest of all.
Now, it's true that these colors are often quite subtle, and seeing them can be challenging since our eye's color receptors don't respond well to faint light. You know this is true if you've ever looked around outdoors after dark and see shades of gray everywhere, but colors are virtually nonexistent.
The same is true with stars. In fact, anyone with the slightest color blindness might miss the stars' colors completely. But there is a place in the heavens where two dramatically tinted stars appear side by side and always elicit "oohs" and "aahs" when viewed through a small backyard telescope. Astronomers know this "binary star" as Beta Cygni, but its proper name is Albireo.
Look for Albireo almost at the center of the Summer Triangle — formed by the three bright stars Deneb, Vega and Altair — midway up in the eastern sky after dark this week. It marks the head of Cygnus, the swan, which stargazers can also recognize as the Northern Cross.
No matter how good our vision, we see Albireo as a single star with unaided eyes. But aim a small telescope in its direction and it'll appear as two separate stars. In 1905, astronomy and writer Agnes Clerke wrote that the "golden and azure" tints of Albireo gave perhaps "the most lovely effect of color in the heavens." Anyone peering at Albireo for the first time will surely agree.
While viewing this beautiful stellar pair, it's fun to contemplate what we're seeing. Albireo's stars not only represent stunning colors, but a fundamental property of stars as well: temperature. One of its components is a yellow star (about 7,700 degrees F) and the other is a bluish star (19,500 F).
The stars of Albireo lie about 400 light years from us and may orbit a common center of gravity. Don't expect to see any movement while you're watching, though. One orbital cycle takes tens of thousands of years to complete. And, if we could transport our planetary family out to this distant binary star, we would find that at least 51 solar systems could be lined up edge to edge between the two stars.
As is often the case in astronomy, the name Albireo has been misunderstood and mistranslated. Arabic texts originally called it "al-Minhar al-Dajajah," meaning "the hen's beak," which is certainly understandable given the location of the star within the celestial bird's body. But Latin scholars misunderstood that the name came from a kind of herb, and translated it as "ab ireo" (meaning "from ireus"). Eventually people considered this a misprint and transcribed it as "al-bireo".
Whatever you call it — al Minhar al-Dajajah, Beta Cygni or Albireo — don't miss this colorful summertime celestial showpiece!
Visit Dennis Mammana at www.dennismammana.com.
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