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Exoplanet Discovery Joshua Pepper Vanderbilt University Keivan Stassun, Rob Siverd, Leslie Hebb, Phil Cargile - Vanderbilt University Rudi Kuhn – The University of Cape Town Scott Gaudi, Thomas Beatty – The Ohio State University Summary • • • • Historical background How do we find exoplanets? Current state of discovery The KELT project A New Field of Exploration Other Galaxies – 1920s Wikimedia Commons Quasars and Black Holes – 1960s-1970s http://www.space.com/bestimg/?guid=4499b3474b769&cat=strangest http://www.fas.org/irp/imint/docs/rst/Sect20/A6.html Cosmic Microwave Background – 1970s-1990s How did we get here? Most of modern history 9…(or 8) planets Now… 8 + 729 planets The Olden Days (pre-1992) All the planets in the Universe… Known since ancient times 1781 1846 1930 Explosion of Discovery 8 + 729 10 5 1700 1800 1900 2000 A New Field of Exploration Dust grains → Brown Dwarfs Sizes: 10-7 m → 107 m Masses: few thousand atoms → 0.08MSun Discovery Methods • Microlensing • Astrometry Background star (source) Foreground star with planet (lens) • Direct Imaging • Radial-Velocity • Transits From Beaulieu, et al. 2006, Nature, 439, 437 Discovery Methods • Microlensing • Astrometry • Direct Imaging • Radial-Velocity • Transits Shift due to terrestrial planet is one microarcsecond 1,000,000 times smaller than the size of the star itself Discovery Methods • Microlensing • Astrometry • Direct Imaging • Radial-Velocity • Transits NASA, ESA, P. Kalas, J. Graham, E. Chiang, E. Kite (University of California, Berkeley), M. Clampin (NASA Goddard Space Flight Center), M. Fitzgerald (Lawrence Livermore National Laboratory), and K. Stapelfeldt and J. Krist (NASA Jet Propulsion Laboratory) Seeing the Earth around the Sun: 10,000,000,000 to 1 Discovery Methods • Microlensing • Astrometry • Direct Imaging • Radial-Velocity • Transits From Bouchy, et al., 2005, A&A, 444, L15 Radial Velocity motion of the sun due to the Earth is 10 cm per second, 0.22 mph. Transits brightness ~1% planet diameter time Finding Transits 1. Monitor all stars and derive lightcurves 2. Search for transit like behavior (computingintensive!) 3. Do follow-up observations to eliminate false positives 4. Confirm planets with full dynamical information Discovery Highlights • Hot Jupiters • Eccentric and inclined orbits • New Planet types planet scattering is common • Puffy giants / Dense giants • Ice and ocean worlds • Super-Earths – metal/gas or water? • Exciting systems – Binary planets – Free floating – Planets in habitable zone, >100 from Kepler already Discovery Highlights • Planet Demographics from Kepler (only for Period < 50 days!) – Metallicity trend holds for gas giants but not Neptunes or terrestrial planets – Neptunes and Super-Earths are common, 30% to 50% of sunlike stars have them – Planets come in packs – Frequency is inversely proportional to stellar mass Directions for Future Discovery • 729 planets discovered (and confirmed) • Two directions for future discovery – Rare, extreme, or valuable – General demographics Verify theories of formation & evolution KELT: The Kilodegree Extremely Little Telescope • 2 Fully Robotic telescopes • 4k x 4k CCD, 9 micron pixels • 4.5 cm aperture • 26 x 26 degree field of view • $60,000 per telescope KELT: The Kilodegree Extremely Little Telescope KELT-North KELT-South Deployed 2005 to Winer Observatory, AZ Deployed 2009 to Sutherland, South Africa Operated by Ohio State and Vanderbilt Operated by Vanderbilt, Fisk University, and the University of Cape Town Fields Observed by KELT 5 years of data 1.5 years of data Blue line – Galactic plane Green line – ecliptic 42% of the sky Discovery Space for KELT Bright (8 < V < 11) stars with transiting planets Opportunity for followup investigations – Break msin(i) degeneracy, get mass and inclination – Planet Radius density composition / core mass – Atmosphere • Transmission spectroscopy • Emission spectroscopy – Spin-orbit alignment (Rossiter-McLaughlin effect) – Moons & Rings How large is 26 degrees, really? 23” x 23” pixels 26 degrees Blind Recovery of Known Planets HD189733b V = 7.67 Rp = 1.18 RJ P = 2.22 days A transit survey and…comets? A transit survey and…comets? Comet Schwassmann-Wachmann-1 KELT Research Program • Primary Science – Bright transiting planets • Secondary Science – Variable stars, especially eclipsing binaries – Solar system science – Combination with other transit surveys KELT-South Telescope