hip-77986

Its story

4 Herculis —also catalogued as V839 Herculis— is a Be star: a hot B-type star wrapped in a disk of gas that the star itself ejects into space through its dizzying rotation. Measurements reveal a 12,500 K surface spinning at more than 300 km/s, and an invisible companion orbiting every 46 days. When the disk forms, the spectrum shows those quasi-emission «shoulders» that betray a star in mid-exhalation.