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Life in the Universe I. astronomy “If you wish to make an apple pie from scratch, you must first invent the Universe.” Carl Sagan (1934-1996) Páll Jakobsson (Palli) ([email protected]) 10 January 2013 1. Inngangur • 1.1 Aaaaa • 1.2 Bbbbb Distance: 25 light years Tracking Fomalhaut b from 2004-2012 Distance: 130 light years 4 M = 9 ∙ MJupiter Distance: 25 light years Distance: 70 light years Known Exoplanets • 1992: a few are discovered around a neutron star! • 1995: the first around Sun-like star (indirect measurement). • January 2013: 854 (http://exoplanet.eu): 1) Radial velocity + astrometry: 498 (386 planetary systems) 2) Transits: 291 (236 planetary systems) 3) Microlensing: 16 (15 planetary systems) 4) Imaging: 32 (28 planetary systems) 1), 2) and 3) are indirect measurements. Venus Transit in June 2012 Transit Graph 9 Transit Graph Provides information on the radius of the exoplanet. 10 Probability of a Transit Detection? 11 Where is Kepler Looking? 12 The Kepler Planet Candidates (~2300) (NB: only 105 confirmed planets) Kepler-20: An Unusual Planetary System (5 planets in small orbits) Kepler-20: large, small, large, small, large Kepler-20b: 1.9 ∙ REarth Kepler-20e: 0.9 ∙ REarth 760 °C Kepler-20c: 3.1 ∙ REarth Kepler-20f: 1.0 ∙ REarth 430 °C Kepler-20d: 2.8 ∙ REarth 16 (the first rocky exoplanet to be discovered) 6 planets! 18 The Habitable Zone (shown in green) 19 Earth 2.0 Kepler-47 (a system with more than one planet orbiting a pair of stars) Astrometry (ísl: stjörnuvagg) • A system of two (or more) bodies orbit around their mutual centre of mass. • The change in the stellar position (wobble) gives the planet mass. • Example: MJupiter and d = 1 AU. Assume the system lies 3 light years from Earth. Stellar wobble: 1 milliarcsecond. • Now put an “Earth” instead and move the system to 30 light years. Stellar wobble: 0.3 microarcsecond. • No chance measuring that today. • SIM PlanetQuest: 2016? 26 Motion of the Sun (distance: 30 ly)