Exoplanets Ioannis Paraskevas

Introduction planets outside the Solar System First exoplanet announced in 1992 More than a thousand such planets have been discovered (1075)  3,568 candidate planets nearest known exoplanet, is Alpha Centauri Bb  confirmed planets are gas giants  

Problems with detection Vast distances Small Dim

Methods of detection Radial velocity Transit method Gravitational microlensing

Radial velocity method by far the most productive method star moves in its own small orbit around the system's center of mass radial velocity can be detected from spectral lines Extremely small radial-velocity variations, 1 m/s or even somewhat less

Transit method second most productive method planet crosses in front of its parent star observed brightness of the star drops by a small amount reveals the radius of a planet

Gravitational microlensing gravitational field of a star acts like a lens magnifies the light of a distant background star  most sensitive to detecting planets around 1–10 AU away from Sun-like stars

Ultimate goal Find : an Earth-like planet Extraterrestrial civilizations

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