The spectrum of this massive star matches a stellar classification of B0.5 IVe. A luminosity class of IV identifies it as a subgiant star that has reached a stage of its evolution where it is exhausting the supply of hydrogen in its core region and transforming into a giant star. The 'e' suffix is used for stars that show emission lines of hydrogen in the spectrum, caused in this case by the circumstellar disk. This places it among a category known as Be stars; in fact, the first such star ever to be so designated. It has 17 times the Sun's mass and is radiating as much energy as 34,000 Suns. At this rate of emission, the star has reached the end of its life as a B-type main sequence star after a relatively brief 8 million years. The outer atmosphere has an intense effective temperature of 25,000 K, which is causing it to glow with a blue-white hue.