ASTR 101 1st Edition Lecture 15 Outline of Last Lecture II Telescopes III Planet detection Outline of Current Lecture I Transits and eclipses II Properties of extrasolar planets Current Lecture I II Transits and eclipses a A transit is when a planet crosses in front of a star This causes the star to look less bright and it also allows us to calculate the planet s radius Eclipse is when a planet crosses behind the star b What wavelength is best to observe the eclipse in the infared It is not too bright because it is a blackbody flux c Kepler The Kepler mission by NASA began looking for transit planets Because they transit themselves the transit only lasts about an hour and then disappears so data points should be collected at least every hour Observation is very difficult Must observe lots of stars to gather accurate results so use a wide field camera so that you can see many bright stars to monitor What properties of extrasolar planets can we measure a Planet density mass volume b In exoplanet study the Doppler will allow you to measure the mass of the planet Must measure the mass to be sure it is a planet c If you know the density you can tell whether it s a gaseous solid or rocky planet d Suppose you found a star with the same mass as the Sun moving back and forth with a period of 16 months What can you conclude it has a planet orbiting at greater than 1 AU These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute
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