The primary star, ε Sagittarii A, of this binary star system has a stellar classification of B9.5 III, with the luminosity class of III suggesting this is an evolved giant star that has exhausted the supply of hydrogen at its core. The interferometry-measured angular diameter of this star, after correcting for limb darkening, is , which, at its estimated distance, equates to a physical radius of about 6.8 times the radius of the Sun. This is a close match to the empirically-determined value of 6.9 solar radii. It has about 3.5 times the mass of the Sun and is radiating around 363 times the Sun's luminosity from its outer atmosphere at an effective temperature of 9,960 K. At this heat, the star glows with a blue-white hue.