Saturday, August 24, 2024

Double Stars in Lyra's Parallelogram (all night)

Each corner of Lyra's parallelogram is marked by a double star. Zeta Lyrae,
the corner closest to the very bright star Vega, can be split with binoculars (orange circle). Both components are white, with one star slightly brighter than the other. Each of these stars also has a partner that is too close together to split visually. Moving clockwise, the southwest corner star is Sheliak, the brightest of a tight little grouping of stars visible in a telescope. Sheliak itself has a close-in, dim companion in an eclipsing binary system with a 13-day period. The hot, blue giant star Sulafat sits at the farthest corner from Vega. 620 light-years-distant Sulafat is much larger than Vega - an old star on its way to becoming an orange giant many years from now. Add the slightly dimmer stars Lambda Lyrae and HD 176051 to its south and
west, respectively to form a naked-eye triple. Delta Lyrae marks the
northeast corner of the parallelogram. Sharp eyes and binoculars will easily split the double into one blue and one red star. The blue star is one hundred light-years farther away than the red one; they just happen to appear close together along the same line of sight.

(Data courtesy of Starry Night)
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* Origin: CJ's Place, Orange City FL > cjsplace.thruhere.net (21:2/156)