Searching For Habitable Exoplanets

Transcription

1 Searching For Habitable Exoplanets Gongjie Li, Harvard -> Georgia Tech Life in the Cosmos, Georgia Tech

2 Credit: ESO

3 Are we alone? How common are we in the Universe? Search for alien civilization. Credit: ESO

4 Detection of Exoplanets

5 Method to Detect Exoplanets Transit method: Credit: NASA

6 Method to Detect Exoplanets Transit method: Credit: NASA Period of dimming Planet-Star Distance

7 Method to Detect Exoplanets Transit method: Credit: NASA Depth of dimming Planet to Star size ratio

8 Method to Detect Exoplanets Radial Velocity method:

9 Method to Detect Exoplanets Radial Velocity method: Image Credit: NASA Period of Doppler Shift Planet-Star Distance

10 Method to Detect Exoplanets Radial Velocity method: Image Credit: NASA Amplitude of Doppler Shift Planet-Star Mass Ratio

11 Architectural Properties

12 Hot Jupiters Architectural Properties Challenge Formation Theories First step in timeline for life on Earth (Hud & Williams talk)

13 Habitability Terrestrial Planets Temperature Allows Liquid Water to Exist on Surface Atmosphere shows biosignatures Dynamical Stability

14 Solar System Planetary Composition and Sizes Credit: Wikipedia

15 Solar System Planetary Composition and Sizes Credit: ESO Rp<1.5R : Terrestrial Rogers et al. 2015

16 Solar System Planetary Composition and Sizes

17 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

18 Habitable Zone Kane et al. 2016

19 Atmosphere of Exoplanets Transit method: A Planet s Transmission Spectrum A Planet s Atmosphere Signatures Credit: NASA

20 Atmosphere of Exoplanets Transit method: A Planet s Transmission Spectrum Credit: NASA Percentage of Transmission Atmosphere Signatures: Existence of water, ozone, etc.

21 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

22 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 HZ terrestrial planets can be characterized in future

23 Dynamical Stability of Exoplanets Systems Credit: SwRI

24 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)

25 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

26 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 Credit: David A. Aguilar

27 Dynamical Stability of Exoplanets Eccentricity and obliquity variations Climate of Planet credit: bismarckcc.org Credit: The Hispanic OutlooK-12 Magazine Inc.

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29 Dynamical Stability of Exoplanets Eccentricity and obliquity variations Climate of Planet Obliquity

30 Dynamical Stability of Exoplanets Earth Stable and beautiful seasons:

31 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

32 Dynamical Stability of Kepler-186f Credit: Danielle Futselaar

33 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 Image credit: NASA Ames

34 Dynamical Stability of Exoplanets Credit: NASA

35 Shan & Li in prep Dynamical Stability of Exoplanets Obliquity variations of Kepler-186f (degree) Earth-analogue (degree) With extra planet time (Myrs) time (Myrs)

36 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

37 Observational Missions: Kepler Spacecraft, covers 0.25% of the sky Credit: NASA

38 Future Observations: e.g., TESS Transiting Exoplanet Survey Satellite Mission type: Space observatory, all-sky transit survey Launch date: March 2018 Credit: NASA/MIT

39 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

40 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

41 Thank you!

42 Detection of Exoplanets Rapid Growth in the number of detected planets

43 Detection of Exoplanets Rapid Growth in the number of detected planets Dominant methods: Transits & Radial Velocity

44 Composition of Planets

45 Future Observations: e.g., TESS, JWST & HabEx

46 Future Observations: e.g., TESS, JWST & HabEx