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Dive into the world of exoplanets - planets orbiting stars beyond our Sun. Learn about groundbreaking discoveries, planet-finding techniques like the Doppler and transit methods, direct observations, and the surprises in exoplanetary systems. Discover the quest for Earth-like planets and the latest Kepler results from surveying stars for candidate planets in the Habitable Zone. Explore the Kepler-11 and Kepler-37 systems and get engrossed in the mysteries of the universe.
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The Discovery of… EXOPLANETS by Kyle Jeter
I. Exoplanet Basics • Extrasolar planets,(exoplanets), are planets orbiting stars other than our Sun. • 1995 - Swiss astronomers Mayor & Queloz discover the first extrasolar planet around the star 51 Pegasi(4 day orbit!)
C. Over 2,000new “exoplanets” have been discovered D. Americans Geoffrey Marcy & Paul Butler discovered many of the first planets incl. 70 Virginis
II. Planet-finding Techniques A. Doppler Method 1. Star “wobbles” due to gravitational tug of planet (Mass can be found) 2. Doppler shift of light from the star is measured, or… 3. ..the star’s movement is measured against the background of stars Ex/ COROT (Dec. 2006)
B. Transit Method (eclipse) 1.Intensity of light may dip as a planet passes in front of its host star 2. Size of planet measured based on this “blink” in the intensity. 3. Combine size from transit method w / mass from Doppler method to find density 4. Must be lined up, though.. (~1-10% of star systems)
5. KEPLER MISSION (2009) a. Detect transits to find planets b. Uses a photometer c.Has found Earth-sized planets!! (2014) d. Launch: 3-5-09
C. Direct observation 1. Spitzer (2005) 2. “Hot Jupiters” discovered 3. SIM (Space Interferometry Mission)
4. Gemini/Keck take 1st direct pictures of exoplanetary system!! (2008) a. 3 planets, 7-13 MJupiter b. Host star, HR 8799 – 1.5 Msun c. System is 130 l.y. away, in Pegasus 5. Hubble directly images 4th exoplanet a. Host star, Fomalhaut ≈ 16 Lsun b. Fomalhaut b ≈ 3 Mjupiter c. 25 l.y. away in Pisces Australis
D. Gravitational microlensing 1. Based on Einstein’s theory 2. First used for planets in 2006 3. “Cold” planet, only 5.5 ME, discovered around very distant star 4. 2 planets found simultaneously in 2008 (6 total found w/ this method) 5. Must be lined up, though..
III. Surprises & the Holy Grail • Surprises *1. Large (Jupiter-sized) planets found very close to their host stars 2. Not many “super-Jupiters” found (10-70 Mjupiter) 3. Many have very eccentric orbits
B. The Holy Grail 1. Astronomers want to discover Earth -like planets 2. First direct spectrograph (2009) a. Looking for water vapor b. Looking for “Free” oxygen c. Looking for Methane, CO2, etc… 3. Terrestrial Planet Finder (20??)
IV. Kepler Results (150,000 stars) • 150,000 stars surveyed • 3600 Candidate planets! • 45+ in Habitable Zone of parent star • 12+ Potential Earth-sized in habitable zone! • Kepler 10b (1-10-11) 1. 1st“Rocky” Planet found by Kepler 2. 1.4 rEarth / 4.6 ME / .84 day orbit! F. Kepler-11 system found w/ 6 planets