Displaying items by tag: Double Stars
Epsilon Lyrae is a a true binary star system with an orbit that is measured in hundred of thousands of years to complete an orbit. In addition, each star is also a binary star that can only be split using higher powers. For this reason, it is often called the Double Double star. In addition an even closer in star has been detected around one of the stars.
Albireo or Beta Cygni, is one of the finest double stars in the northern hemisphere. Located at the "beak" of Cygnus the Swan, the two stars show a vivid contrast in color. Although the two stars don't seem to be a true binary due to their distance between them and their motion across the sky. Just two stars passing in the night. However both stars do have companion stars that are too close in to be resolved by optical means.
Here we have HD79210, a double star located 20 light years away in the constellation Ursa Major. The pair of stars orbit each other once every 975 years. The primary star is a magnitude 7.64, and the secondary star is 7.70, so they both about the same brightness. They both are slightly cooler of the Sun, being K, and M class stars which are orange-red dwarf stars.
Many stars have orbiting companions, most are too far away, or orbit too close to see, other than by spectroscopic observation. Our Sun is in the minority in that it has no known stellar companions.
Imaged under a full Moon, using 120 second exposures for each red, green, and blue filters.