A distant star system is discovered in which a planet with twice the radius of the earth and rotating 3.0 times as fast as the earth orbits a star with a total power output of 6.8 × 10²⁹ W.
a. If the star’s radius is 6.0 times that of the sun, what is the electromagnetic wave intensity at the surface? Astronomers call this the surface flux. Astronomical data are provided inside the back cover of the book.
b. Every planet-day (one rotation), the planet receives 9.4 × 10²² J of energy. What is the planet’s distance from its star? 

Give your answer in astronomical units (AU), where 1 AU is the distance of the earth from the sun.