Gamma Arae

Properties

This enormous star has 14 times the Sun's radius and radiates 120,000 times the Sun's energy from its outer envelope at an effective temperature of 21,240 K, giving it the blue-white glow of a B-type star. Its spectrum matches a stellar classification of B1 Ib, with the luminosity class 'Ib' indicating a lower luminosity supergiant. It is a relatively young body, with an estimated age of around 15.7 million years. Gamma Arae rotates rapidly with a projected rotational velocity of 269 km s⁻¹, completing a full rotation about every 4.8 days; this high spin causes absorption lines to blend together due to the Doppler effect, making them more difficult to analyze. It is a periodically variable star that undergoes non-radial pulsations with a primary period of 1.1811 days and a secondary period of 0.1281 days. There is disagreement about the star's mass in the literature: Tetzlaff et al. estimate 12 solar masses, Fraser et al. give around 19, and Lefever et al. list 25. It sheds mass through its stellar wind at a rate equivalent to losing the Sun's mass every 33 million years, and the wind is affected by the star's rapid rotation, resulting in enhanced outflow along the equator.