Event Date: September 21st
Time: 8:34(.22) PM
Brief
There is a spectacular double star in Cygnus--within Summer Triangle boundaries--which I have failed to acknowledge all summer long--shame on me! It is Albireo, which to people who live in the San Francisco Bay Area--if not beyond--is also called the "Cal" star(s): one blue, one yellow, er...gold*. How deep a yellow color may depend on how powerful one's telescope is, and/or whether or not a person is looking at the pair during a stage of twilight or complete darkness. Nonetheless, when a viewer points to Albiereo, it is a sight not to be forgotten. Granted many, or to certain people, most stars are boring to look at in comparison to planets, clusters, nebulae and the closer galaxies. To prove otherwise with Albireo, here is a zoom in at transit time, preceded by a zoom-out to show its position relative to the other Summer Triangle stars: Vega, Altair and Deneb.
The zoom-in is about 270x magnified to show them separated, yet in even the small telescopes at 1/3rd of this magnification, the color and separation is easy to detect. Of course with the eye, they appear as one, and color is difficult to detect on even the clearest of nights.
Time: 8:34(.22) PM
Brief
There is a spectacular double star in Cygnus--within Summer Triangle boundaries--which I have failed to acknowledge all summer long--shame on me! It is Albireo, which to people who live in the San Francisco Bay Area--if not beyond--is also called the "Cal" star(s): one blue, one yellow, er...gold*. How deep a yellow color may depend on how powerful one's telescope is, and/or whether or not a person is looking at the pair during a stage of twilight or complete darkness. Nonetheless, when a viewer points to Albiereo, it is a sight not to be forgotten. Granted many, or to certain people, most stars are boring to look at in comparison to planets, clusters, nebulae and the closer galaxies. To prove otherwise with Albireo, here is a zoom in at transit time, preceded by a zoom-out to show its position relative to the other Summer Triangle stars: Vega, Altair and Deneb.
The zoom-in is about 270x magnified to show them separated, yet in even the small telescopes at 1/3rd of this magnification, the color and separation is easy to detect. Of course with the eye, they appear as one, and color is difficult to detect on even the clearest of nights.
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| click on images to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp. |
Detailed
Although I didn't include the meridian in image one, which would obstruct Albireo almost completely, its transit time can remind us of something I talked about earlier this year a few times: the transit time of the Triangle's "center". This evening, that time is about 8:45, or 11 minutes after Albireo's transit time. That isn't too important to remember, unless you are a transit-comparison nerd the way I am sometimes! :-P
As for some characteristics worth knowing about Albireo, the stars are two different magnitudes: 3 for the gold, 5 for the blue (dwarf). At only 35 arc-seconds apart, that is why they are too difficult to see apart from each other with the eye alone, which can perhaps only detect 1 or 2 arc-minutes apart at best for some doubles in the clearest darkest of skies. However, they are about 7 light years apart, meaning that if a binary system, they could take close to 100,000 years to revolve around each other. Even closer together, are the gold with a companion of its own. This star creates a spectrum, which proved its existence; that is good, since telescopes on Earth would have to be powerful enough to split the star, and such are not easily portable .
As we enter our last hours before the September equinox, enjoy this "jewel" of a double, with the blue and gold together and, oh yeah...go bears!**
*University of California Berkeley
**UCB's team
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