sábado, 25 de mayo de 2013

Albireo is one of the sky’s finest double stars


Albireo is known best for the striking color contrast between its two stars, with the brighter star gold and the dimmer star blue.


The modestly bright star Albireo – representing the Eye or sometimes the Beak in the constellation Cygnus the Swan – looks like a single point of light to the unaided eye. But peer at this star through the telescope, and you’ll easily discover why Albireo wins universal praise for being the finest double star for the small ‘scope. Best viewed at 30X (“30 power” or a magnification of 30), Albireo is known best for the striking color contrast between its two stars, with the brighter star gold and the dimmer star blue. Albireo – which is also called Beta Cygni – is probably a true binary star. In other words, its two stars probably revolve around a common center of mass. Albireo’s two stars lie quite far apart, however, and might take as long as 75,000 years to orbit one another. Even though these two stars appear close together in a telescope, keep in mind that you’re looking at a system that’s 380 light-years away.




To find Albireo, use the brilliant signpost of the summer and autumn sky: the Summer Triangle asterism. Look in between the first-magnitude stars Vega and Altair for the third-magnitude star Albireo. If you are familiar with the clipped version of Cygnus – the Northern Cross – Albireo marks the base of the Cross. Albireo isn’t particularly bright, but it’s the brightest star in this area of the heavens, and is easily visible in a dark country sky. Once you’ve viewed one of the most majestic double stars that the sky has to offer, let Albireo act as your guide to the Coathanger, a star pattern that rates as a binocular favorite

source and credit a earthsky