Albireo is 380 HYPERLINK http//en.wikipedia.org/wiki/Light-year o Light-year light-years (120 HYPERLINK http//en.wikipedia.org/wiki/Parsec o Parsec pc) away from the Earth. When viewed with the naked eye, it appears to be a single star. However, in a HYPERLINK http//en.wikipedia.org/wiki/Telescope o Telescope telescope it readily resolves into a HYPERLINK http//en.wikipedia.org/wiki/Double_star o Double star double star, consisting of Albireo A (amber, HYPERLINK http//en.wikipedia.org/wiki/Apparent_magnitude o Apparent magnitude apparent magnitude 3.1), and Albireo B (blue-green, apparent magnitude 5.1.) HYPERLINK http//en.wikipedia.org/wiki/Albireo l cite_note-msg-9 10 Separated by 35 seconds of arc, HYPERLINK http//en.wikipedia.org/wiki/Albireo l cite_note-wdsb-10 11 the two components provide one of the best contrasting double stars in the sky due to their different colors. It is not known whether the two components are orbiting around each other in a physical HYPERLINK http//en.wikipedia.org/wiki/Binary_star o Binary star binary system. If they are, their orbital period is probably at least 100,000 years. HYPERLINK http//en.wikipedia.org/wiki/Albireo l cite_note-msg-9 10 ALBIREO (Beta Cygni). One of the great small-telescope showpieces of the sky, Albireo, the third-magnitude (3.0) Beta star of HYPERLINK http//stars.astro.illinois.edu/sow/cyg-p.html Cygnus, the Swan, is a magnificent visual HYPERLINK http//stars.astro.illinois.edu/sow/star_intro.html l doubles double whose components (magnitudes 3.3 and 5.5) have contrasting golden and blue colors. Though given the second letter of the HYPERLINK http//stars.astro.illinois.edu/sow/greek.html Greek alphabet, the star actually comes in at number five in brightness, beaten out by HYPERLINK http//stars.astro.illinois.edu/sow/deneb.html Deneb (Alpha Cygni), HYPERLINK http//stars.astro.illinois.edu/sow/sadr.html Sadr (Gamma), HYPERLINK http//stars.astro.illinois.edu/sow/gienahcyg.html Gienah (Epsilon), and HYPERLINK http//stars.astro.illinois.edu/sow/deltacyg.html Delta. Star colors are usually subtle, ranging from a warm orange red to a hint of blue on white depending on the viewers eyes. But put a star of one color next to one of another, and the eye seems to exaggerate both, delighting the follower of double-star astronomy. Waxing romantic, astronomers have called the pair topaz and sapphire. With a separation of 34 seconds of arc, the pair is easily seen at low telescopic power. The name has a magnificently confused and mistranslated origin, and means nothing at all with regard to its position at the head of Cygnus the Swan. Albireo beautifully shows how an apparently single star as viewed through the telescope can actually be double, such binary stars appearing all over the sky. Somewhere around half, or even more, of the local stars are actually members of some kind of double or multiple system, the stars in orbit about each other. The stars that make Albireo, about 380 light years away, are quite far apart however, and if actually attached gravitationally have an extremely long orbit with a period of at least 75,000 years. Albireo is actually triple. The brighter yellow-colored member, Albireo A, is a much closer double made of a third magnitude (3.3) class K (K3) stable helium-fusing bright giant and a hotter but dimmer (magnitude 5.5) class B (B9) hydrogen-fusing dwarf, the two stars not readily separable in the telescope. The K giant has a temperature of around 4400 Kelvin, a luminosity 950 times that of the HYPERLINK http//stars.astro.illinois.edu/sow/sun.html Sun, a radius 50 times solar, and a hefty mass of about 5 solar, while the close companion comes in at 11,000 Kelvin, 100 solar luminosities, and 3.2 solar masses. On average separated by about 40 Astronomical Units, they take almost 100 years to go about each other on a highly eccentric orbit. The visually-seen blue star, Albireo B, is similar to Albireo As companion, and is a class B (B8) dwarf