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Unformatted text preview: Astronomy 210 Homework Set #7 Due in class: Friday, March 17 1. A Transiting Exoplanet . NASA’s Kepler space telescope is designed to find transiting planets, that is, planets whose orbit planes happen to be seen edgeon, 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 newlydiscovered transiting exoplanet Kepler7b. 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 Kepler7b. From the known mass of the host star, and the orbital period, use Newton’s form of Kepler’s law is a 3 = GMP 2 / (4 π 2 ), and to find the planet’s 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 star’s and planet’s 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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 Spring '08
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 Astronomy, Space

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