Sig

Its story

Sigma Aquilae is an eclipsing binary some 780 light-years away, made of two near-twin blue B3 V stars that eclipse each other every 1.95 days with clockwork precision. The primary burns at 18,493 K, radiates 1,862 times the Sun's light and carries 5.8 solar masses. Each eclipse dims the pair by two-tenths of a magnitude: a regular pulse at the heart of the Eagle, discovered in the early twentieth century and refined ever since.