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This document reviews key conditions necessary for life on habitable planets, including the presence of liquid water and favorable atmospheric conditions. It discusses the significance of radial velocity variations in relation to gas giant planets, emphasizing measurement methods used to validate planetary candidates identified through transit observations. The challenges of direct imaging of exoplanets due to stellar brightness are highlighted, along with the principles of microlensing as a detection method based on Einstein's theory of relativity.
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Test question 17.1 • Presence of liquid water on a habitable planet requires • xEmergenceof life • xOutgasingfrom planetary interior • xPolarcaps • vModeratetemperature and sufficient atmospheric pressure
Test question 17.2 • A sun-like stars is observed to undergo periodic radial velocity variations of 10 m/s on a timescale of a year. If this is the reflex motion of a gas giant planet with one thousandth the mass of the Sun, the orbital speed of this planet would be • v10 km/s • x330 m/s • xSameas the star • x0.1 m/s
Test question 17.3 • During a planet transit event, the host star HIDE dimmed by about 1%. The radius of the planet is • xSameas the Earth • v10% that of the star • x1% that of the star • x0.1% that of the star
Test question 17.4 We need to use radial velocity measurements to verify planetary candidates found through transit observations by the Kepler mission because • xWeneed to see their images • vWeneed to eliminate possible false signals such as background binary stars • xWeneed to test Newton’s theory of gravity • xWeneed to see the evolution of these planets’ orbits.
Test question 17.5 • Transit observations can be used to measure: • xPlanets’ size • xOrientationof stellar spin relative to the planets’ orbit • xPlanets’ atmospheric composition • vAllof the above
Test question 17.6 Microlensing survey of planets is based on the principle of • xParallex, ie looking at distant objects from different location of the orbit. • xDoppler’seffect • xAdaptiveoptics • vEinstein’stheory of relativity
Test question 17.7 Direct imaging of extra solar planets is challenging because • xPlanetsare always moving, • xPlanets’ color and luminosity are always changing • vPlanets’ light is greatly outshined by their host stars which also appear to be close to them in the sky • xMostextra solar planets appear in the sky during the day time on the Earth.