Phi Persei: Double Star . ... Based on recent results , this artist's vision of the double star Phi Persei , 720 light years away, shows a bright, rapidly rotating massive star surrounded by a disk of gas. A small companion star orbits 100 million miles away. ... Ten million years ago the small companion was actually the most massive star in the system and because of its greater mass evolved into a giant star more quickly. ... NASA Web Site Statements, Warnings, and Disclaimers . ...