One of the great discoveries in astronomy in the past

Chapter , Problem 20

(choose chapter or problem)

One of the great discoveries in astronomy in the past decade is the detection of planets outside the solar system. Since 1996, more than 100 planets have been detected orbiting stars other than the Sun. While the planets themselves cannot be seen directly, telescopes can detect the small periodic motion of the star as the star and planet orbit around their common center of mass. (This is measured using the Doppler effect, which is discussed in Chapter 15.) Both the period of this motion and the variation in the speed of the star over the course of time can be determined observationally. The mass of the star is found from its observed luminance and from the theory of stellar structure. Iota Draconis is the eighth brightest star in the constellation Draco. Observations show that a planet, with an orbital period of is orbiting this star. The mass of Iota Draconis is (a) Estimate the size (in AU) of the semimajor axis of this planets orbit. (b) The radial speed of the star is observed to vary by Use conservation of momentum to find the mass of the planet. Assume the orbit is circular, we are observing the orbit edge-on, and no other planets orbit Iota Draconis. Express the mass as a multiple of the mass of Jupiter.