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Earth 2.0: NASA's Search for Earth-Size Planets Daniel Dale Physics & Astronomy University of Wyoming

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Earth 2.0: NASA's Search for Earth-Size Planets Daniel Dale Physics & Astronomy University of Wyoming Earth 2.0: NASA's Search for Earth-size Planets Daniel Dale Physics & Astronomy University of Wyoming Image credit: NASA Outline The Kepler mission Target Technique Results Outline The Kepler mission Target Technique Results 1571-1630 What fraction of stars in our galaxy harbor potentially habitable, Earth-size planets? The “habitable zone” Image: NASA The “habitable zone” Image: NASA The Drake Equation N = R* · f · n · f · f · f · L p e l i c Where: • N = # civilizations in Galaxy w/detectable electromagnetic emissions • R* = Rate of star formation suitable for the development of intelligent life • fp = Fraction of those stars with planetary systems • ne = Number of planets, per solar system, with environment suitable for life • fl = Fraction of suitable planets on which life actually appears • fi = Fraction of life-bearing planets on which intelligent life emerges • fc = Fraction of civilizations that develop a technology that releases detectable signs of their existence into space • L = Length of time such civilizations release detectable signals into space Kepler launch 06 March 2009 Cape Canaveral Delta II rocket 0.95 m mirror Outline The Kepler mission Target Technique Results Where does Kepler search? Image: NASA Where does Kepler search? Where does Kepler search? Image: NASA Outline The Kepler mission Target Technique Results Exoplanet Detection Methods Radial velocity Pulsar timing Direct imaging Gravitational microlensing Transit Polarimetry Astrometry Exoplanet Detection Methods Radial velocity Image: European Southern Observatory Exoplanet Detection Methods Radial velocity Preferentially detects large, close-in planets Only provides lower limit to mass Image: European Southern Observatory Exoplanet Detection Methods Pulsar timing quite rare & inhospitable 1991 blooper Images: Alex Wolszczan (Penn St.) Exoplanet Detection Methods Direct imaging Prefers infrared- bright planets far from faint stars Image: European Southern Observatory Exoplanet Detection Methods Gravitational microlensing Best for orbits that are 1-10 AU Not repeatable Image: Malyszkz How does Kepler search? Transit photometry 150,000 stars observed Planets may occult their parent star Image: NASA The first recorded transit of Venus Image credit: Ford Madox Brown, mural at Manchester Town Hall How does Kepler search? Transit photometry Kepler provides planetary “candidates” Ideally confirmed by another technique 10% false positives: Tightly bound or dim binary star companion Stellar pulsations Periodic instrumental glitches Image: NASA Image: wikipedia Image: # Detected Exoplanet Detection Methods Detection Exoplanet Year Image credit: NASA Outline The Kepler mission Target Technique Results Image: NASA Image: Size Relative to Earth Transiting planets pre-Kepler Transiting Orbital period (days) Image: NASA Image: Size Relative to Earth Candidates as of June 2010 June as of Candidates Jun 2010 Jun Orbital period (days) 29 29 Image: NASA Image: Size Relative to Earth Candidates as of Feb 2011 Feb as of Candidates Jun 2010 Jun Orbital period (days) Feb 2011 Feb 30 Image: NASA Image: Size Relative to Earth Candidates as of Dec 2011 of Dec as Candidates Jun 2010 Jun Orbital period (days) Feb 2011 Feb Dec 2011 Dec 31 Image: NASA Image: Size Relative to Earth Candidates as of Jan 2014 of Jan as Candidates Orbital period (days) Image credit: NASA/W Stenzel Kepler's habitable zone planets Kepler 62 system Image credit: NASA Ames/JPL-Caltech Kepler's smallest habitable zone planet Kepler 62f 1200 lyr away (Lyra) 40% larger than Earth 267 day orbit Image credit: NASA Ames/JPL-Caltech/Tim Pyle 22% of Sun-like stars harbor Earth-size planets orbiting in their habitable zones (Petigura et al. 2013) Image: NASA Extrapolate the result to the entire Milky Way: 40 billion habitable Earth-size planets (Petigura et al. 2013) Image: NASA Transit and Doppler Measurements Yield Density + 10b Size Density Mass = 8.8 g/cm3 Volume Image: NASA Image: NASA The Drake Equation N = R* · f · n · f · f · f · L p e l i c Where: • N = # civilizations in Galaxy w/detectable electromagnetic emissions • R* = Rate of star formation suitable for the development of intelligent life • fp = Fraction of those stars with planetary systems • ne = Number of planets, per solar system, with environment suitable for life • fl = Fraction of suitable planets on which life actually appears • fi = Fraction of life-bearing planets on which intelligent life emerges • fc = Fraction of civilizations that develop a technology that releases detectable signs of their existence into space • L = Length of time such civilizations release detectable signals into space The Drake Equation N ~ 10 · 1 · 0.2 · ? · ? · ? · ? Where: • N = # civilizations in Galaxy w/detectable electromagnetic emissions • R* = Rate of star formation suitable for the development of intelligent life • fp = Fraction of those stars with planetary systems • ne = Number of planets, per solar system, with environment suitable for life • fl = Fraction of suitable planets on which life actually appears • fi = Fraction of life-bearing planets on which intelligent life emerges • fc = Fraction of civilizations that develop a technology that releases detectable signs of their existence into space • L = Length of time such civilizations release detectable signals into space The Drake Equation Progressing from left to right, the equation is increasingly uncertain. Many consider this equation to simply be conceptual, something to start a conversation on how to approach a search for life. Fermi Paradox: Where are they? Kepler Exoplanets By the Numbers Candidates: 4234 July 2014 (3845 April 2014) Confirmed: 978 July 2014 (961 April 2014) Estimated Galaxy Total: 40 billion 22% of Sun-like stars harbor Earth-size, habitable planets Nearest: Alpha Centauri Bb at 4 lyr Least massive: 2 lunar masses Most massive: 29 Jupiter masses Orbital periods: few hours to thousands of years Thank You Kepler's Future Kepler experienced 2 reaction wheel failures (July '12; May '13) No longer can point with the requisite accuracy It is now carrying out its “K2” mission Relies on pressure from sunlight to serve as the “third wheel” and to balance the 'scope Image credit: NASA/W. Stenzel.
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