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Extrasolar Planets. This exoplanet orbiting 51 pegasi is being vaporized by its’s parent star. A new Field to Study. Fundamental Astronomy questions Do other worlds exist? (last 15 years) Is there life on other worlds? (next 15 years). Extrasolar Planet .
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Extrasolar Planets This exoplanet orbiting 51 pegasi is being vaporized by its’s parent star
A new Field to Study • Fundamental Astronomy questions • Do other worlds exist? (last 15 years) • Is there life on other worlds? (next 15 years)
Extrasolar Planet • A Planet that orbits a star outside of our solar system • The picture is a drawing of Gliese 581 C (a star in a habitable zone)
Extrasolar Systems Numbers • 400 extrasolar systems • 8 terrestial planets • 182 gas giants • 77 jupiters • 2 neptunes • 5 pulsar planets • 3 kuiper belts • 2 asteroid belts • 14 forming solar systems with newly formed planets
Properties of known extrasolar systems • Why are most exoplanets gas giants that orbit close to the parent star? • Our current detection methods are biased towards finding gas giants close to a star • It is hard to find terrestrial planets
Challenges for Observing extrasolar planets • Planets do not produce any light of their own • Planets are very far away • Glare from parent stars hide the planets • Closest planets to our solar system have never even been seen (we watch the star)
Dectection Methods • Astronomic and Radial Velocity (235 systems) • Transit Method (46 systems) • Microlensing (6) • Pulsar timeing (3)
Astrometric • Measures a stars position in the sky and observing how it changes over time • Gravitational pull of planet will cause the star to move in a tiny circle • Called “wobbling”
Astrometric Method • 1 telescope can search many stars at a time • Does not work for far away stars • Difficult to detect terrestrial planets which are smaller • SLOW PROS CONS
Radial velocity • Doppler effect • The change in frequency of a wave as perceived by a moving observer • Move towards (waves bunch up) • Move back (waves spread out )
Doppler Effect • Works for all kinds of waves (including light) • Instead of pitch changing, color changes • Blue shift (object approaching) • Red Shift (object Receding)
http://www.youtube.com/watch?v=Man9ulEYSgk • http://www.youtube.com/watch?v=imoxDcn2Sgo
Radial Velocity Method • Measure the slight changes of a stars velocity as the star and planet move • When the star moves, the doppler shift of the starlight can be analyzed • Bigger the planet, bigger the doppler shift
RVM • Can be used for far away stars • Can only observe 1 star at a time • Difficult to detect terrestrial planets • SLOW PROS CONS