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Unformatted text preview: Astronomy 210 Homework Set #7 Due in class: Friday, March 17 1. A Transiting Exoplanet . NASAs Kepler space telescope is designed to find transiting planets, that is, planets whose orbit planes happen to be seen edge-on, so that the planet passes in front of its host star. The planet thus partially eclipses the star, an event known as a transit. Here we consider the newly-discovered transiting exoplanet Kepler-7b. You will see that you can reproduce all of the professional results for this planet. Of course, show your work in your calculations. (a) [5 points] On the web, go to the Exoplanet page at exoplanets.org . In the table of planets, find the information on the planet Kepler-7b. From the known mass of the host star, and the orbital period, use Newtons form of Keplers law is a 3 = GMP 2 / (4 2 ), and to find the planets semimajor axis a in AU. Your result should agree with the professional answer! (b) [5 points] Now assume the planet is in a circular orbit. You showed in HW4 that the stars and planets distance from the COM, r and r p , are related by r + r p = a , and by m r = m p r p . Use these to show that the orbital speed of the star about the COM is....
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