Finding Exoplanet5

Finding Exoplanet5 - if they observed the Sun's motion very...

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Finding Exoplanets Another way to look for exoplanets is to notice their gravitational effect on the stars they orbit. One signature of a planet would be that the star would appear to wobble about as the star and the planet orbit a point situated between them, proportionally closer to the more massive star, called the center of mass . This technique is called the astrometric technique . Our Sun wobbles because of the gravity of the planets orbiting it. Most of the wobble is due to Jupiter which contains more mass than all of the other planets combined. However, the wobble is tiny! Because the Sun is over a thousand times more massive than Jupiter, the center of mass is over a thousand times closer to the Sun, or about 47,000 kilometers above the surface of the Sun (this distance is less than 7% the radius of the Sun). Despite the tiny wobble, astronomers on planets orbiting nearby stars could detect this wobble using the same technology we have here on Earth
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Unformatted text preview: if they observed the Sun's motion very carefully over a couple of decades. The stronger the gravity between the star and planet, the larger will be the wobble of the star and the easier to detect. Therefore, the astrometric technique is well-suited to finding massive jovian exoplanets close to their parent stars. No exoplanets have been found using this technique (at the time of writing). The now-canceled SIM Lite mission was to use this technique and the Gaia mission , scheduled to launch in 2013, will use this technique. Sequence on the right side is actually from two different vantage points. The wobbling star is what you would see if the orbit was face-on. The doppler shifting absorption lines is what you would see if the orbit was edge-on from a position to the right of the star-planet system (so the lines shift toward the red end when the star is moving away from the observer and the exoplanet is moving toward the observer)....
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This note was uploaded on 12/15/2011 for the course AST AST1002 taught by Professor Emilyhoward during the Fall '10 term at Broward College.

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