Searching For Habitable Exoplanets Gongjie Li, Harvard -> Georgia Tech Life in the Cosmos, Georgia Tech
Credit: ESO
Are we alone? How common are we in the Universe? Search for alien civilization. Credit: ESO
Detection of Exoplanets
Method to Detect Exoplanets Transit method: Credit: NASA
Method to Detect Exoplanets Transit method: Credit: NASA Period of dimming Planet-Star Distance
Method to Detect Exoplanets Transit method: Credit: NASA Depth of dimming Planet to Star size ratio
Method to Detect Exoplanets Radial Velocity method:
Method to Detect Exoplanets Radial Velocity method: Image Credit: NASA Period of Doppler Shift Planet-Star Distance
Method to Detect Exoplanets Radial Velocity method: Image Credit: NASA Amplitude of Doppler Shift Planet-Star Mass Ratio
Architectural Properties
Hot Jupiters Architectural Properties Challenge Formation Theories First step in timeline for life on Earth (Hud & Williams talk)
Habitability Terrestrial Planets Temperature Allows Liquid Water to Exist on Surface Atmosphere shows biosignatures Dynamical Stability
Solar System Planetary Composition and Sizes Credit: Wikipedia
Solar System Planetary Composition and Sizes Credit: ESO Rp<1.5R : Terrestrial Rogers et al. 2015
Solar System Planetary Composition and Sizes
Habitable Zone credit: bismarckcc.org Temperature Suitable for Liquid Water Credit: The Hispanic OutlooK-12 Magazine Inc. e.g., Chemistry of life functions in water Hud s talk
Habitable Zone Kane et al. 2016
Atmosphere of Exoplanets Transit method: A Planet s Transmission Spectrum A Planet s Atmosphere Signatures Credit: NASA
Atmosphere of Exoplanets Transit method: A Planet s Transmission Spectrum Credit: NASA Percentage of Transmission Atmosphere Signatures: Existence of water, ozone, etc.
Atmosphere of Exoplanets Super Earth GJ 1214 b, possible water-world Super Earth: 7 M, 2.7 R Atmosphere likely dominated by water vapour. Berta et al. 2012
Atmosphere of Exoplanets Super Earth GJ 1214 b, possible water-world Super Earth: 7 M, 2.7 R Atmosphere likely dominated by water vapour. Berta et al. 2012 HZ terrestrial planets can be characterized in future
Dynamical Stability of Exoplanets Systems Credit: SwRI
Dynamical Instability of Exoplanets Ejection or collision with companion planets/host star Artist Impression of a free floating planet (Credit: J. B. Pullen) Free-floating planets 25% as common as stars (Mróz et al. 2017)
Future Evolution of Kepler-56 Engulfment of inner 2 planets: Kepler 56 b: at 129Myr Kepler 56 c: at 155 Myr Gongjie Li et al. 2014c
Dynamical Instability of Exoplanets Ejection or collision with companion planets/host star Star Will Swallow Two Planets Engulfment of Kepler-56b,c Li et al. 2014 Credit: David A. Aguilar
Dynamical Stability of Exoplanets Eccentricity and obliquity variations Climate of Planet credit: bismarckcc.org Credit: The Hispanic OutlooK-12 Magazine Inc.
Dynamical Stability of Exoplanets Eccentricity and obliquity variations Climate of Planet Obliquity
Dynamical Stability of Exoplanets Earth Stable and beautiful seasons:
Dynamical Stability of Exoplanets Earth Snowball Earth 22.1 Mars obliquity is chaotic, and likely leads to the collapse of its atmosphere Image credit: Michael Pidwirny
Dynamical Stability of Kepler-186f Credit: Danielle Futselaar
Dynamical Stability of Exoplanets Kepler-186f: 1.1 R (first validated Earth-size planet in the habitable zone) P = 130 days M* = 0.5 M 500 lyr from Earth Quintana et al. 2014 Image credit: NASA Ames
Dynamical Stability of Exoplanets Credit: NASA
Shan & Li in prep Dynamical Stability of Exoplanets Obliquity variations of Kepler-186f (degree) 90 80 70 60 50 40 30 20 10 Earth-analogue (degree) 90 80 70 60 50 40 30 20 10 With extra planet 0 0 5 10 time (Myrs) 0 0 2 4 6 8 10 time (Myrs)
Observational Missions: Kepler Spacecraft Mission type: Space observatory Launch date: March 7, 2009 Credit: NASA Candidates: 4,496 Confirmed: 2,337 Small Habitable Zone Confirmed: 30
Observational Missions: Kepler Spacecraft, covers 0.25% of the sky Credit: NASA
Future Observations: e.g., TESS Transiting Exoplanet Survey Satellite Mission type: Space observatory, all-sky transit survey Launch date: March 2018 Credit: NASA/MIT
Future Observations: e.g., TESS Transiting Exoplanet Survey Satellite Mission type: Space observatory, all-sky transit survey Launch date: March 2018 Monitor > 200,000 stars Expected to discover >3,000 exoplanets 20 super-earths in the habitable zone Credit: NASA/MIT
Future Observations: e.g., TESS Transiting Exoplanet Survey Satellite Circumbinary Planets (TESS CBP WG) Mission type: Space observatory, all-sky transit survey Launch date: March 2018 Monitor > 200,000 stars Expected to discover >3,000 exoplanets 20 super-earths in the habitable zone Credit: Lynette R. Cook Credit: NASA/MIT
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Detection of Exoplanets Rapid Growth in the number of detected planets
Detection of Exoplanets Rapid Growth in the number of detected planets Dominant methods: Transits & Radial Velocity
Composition of Planets
Future Observations: e.g., TESS, JWST & HabEx
Future Observations: e.g., TESS, JWST & HabEx