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Exoplanets Searching for New Worlds Larry Morgan

Exoplanets Searching for New Worlds Larry Morgan. Exoplanets. “(There are) countless suns and countless Earths all rotating around their suns” - Giordano Bruno, 1584 Speculation since Ancient Greeks Proposed by Isaac Newton in 1713 Various claims of discovery since 1855

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Exoplanets Searching for New Worlds Larry Morgan

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  1. Exoplanets Searching for New Worlds Larry Morgan

  2. Exoplanets • “(There are) countless suns and countless Earths all rotating around their suns” - Giordano Bruno, 1584 • Speculation since Ancient Greeks • Proposed by Isaac Newton in 1713 • Various claims of discovery since 1855 • First confirmed detection 1988 by Bruce Campbell, G. Walker and S.Yang

  3. Campbell, Walker & Yang discovered a massive planet using the radial-velocity method However, first convincing exoplanet discovered in 1992 by Wolszczan and Frail by pulsar timing method

  4. Detection Methods • Radial Velocity Method

  5. Doppler Shift

  6. Detection Methods • Radial Velocity Method

  7. Detection Methods • Radial Velocity method

  8. Pulsar Timing

  9. Transit Method • Most popular and ‘easiest’ • Very powerful, especially when combined with radial velocity method

  10. Transit Method • Mass, period and composition determinable • corollary - reflected/refracted light direct measurement of atmospheres possible

  11. First exoplanetary atmosphere detections were of sodium • Sodium easy to detect, first milestone toward other chemicals • Light from the star passes through the atmosphere of the planet on its way to us • The original starlight can be filtered out to leave only the effects of the planetary atmosphere • This method originally dates from around 300 years ago

  12. Selection Effects • Estimated 10 billion planetary systems in our Galaxy (100 billion stars) • As of January 2009 there are 335 exoplanets known • Science still in early phases

  13. ‘Hot Jupiters’ • Our current methods of detection work best for big planets close in to their stars • Nearly all exoplanets currently discovered are bigger than Jupiter, the biggest planet in our system • Most of these are closer to their star than Mercury is to the Sun

  14. Massive Exoplanets

  15. Why so Big? • Why are so many exoplanets large and close in? • Nearly all methods of detection most sensitive to higher mass & shorter orbits

  16. Radial Velocity • Pulsar Timing • Photometry - Transit

  17. Eccentricity • Majority of known exoplanets have eccentric orbits • Inexplicable by selection effects

  18. Earth-like Exoplanets • As of August 2008 only 12 exoplanets have masses less than 10 Earths • The fact that any ‘Earth-like’ exoplanets have been discovered at all indicates that they are probably very common • According to one experiment, 1 in 14 stars may be host to ‘Hot Jupiters’ while 1 in 3 host rocky Earths

  19. Sexier Stuff • Attitudes within the Astronomical community have steadily changed over the last ten years, at least outwardly • Professed goal of planet-finding is now regularly stated as ‘finding life’ • The progression towards smaller, more Earth-like planets leads to an almost inevitable conclusion

  20. Aliens!!

  21. SETI • The Search for Extra-Terrestrial Intelligence • www.seti.org • SETI@home • Dyson Spheres

  22. Dyson Spheres • Artificial structure, capturing most or all of a star’s energy output • Such a structure would output a recognisable thermal signature • Scientists at Fermilab have so far identified 17 candidates from more than 10,000 observations

  23. Dyson Spheres • “I think the search... is looking for a needle in a field of haystacks, when you’re not even sure there’s a needle there.” • “If you can build a Dyson sphere, then you don’t need it.”

  24. More Relevant Issues • Percentage of ‘Earths’ • Habitable zones • Planetary habitability • Planetary atmospheres

  25. Habitable Zones • The Circumstellar Habitable Zone is the region of space in which life would be favourable for life as found on Earth

  26. Habitable Zones • Criticisms • We have very little knowledge of what life on other planets might need to evolve, carbon-based or otherwise • Circumstances might mean that favourable conditions might develop outside the CHZ (e.g.Europa) • Breathable atmosphere requires plant life (photosynthesis) • Planets move, life can adapt (though more likely if a planet has moved out of CHZ)

  27. Planetary Habitability • NASA has defined the principal habitability criteria as “extended regions of liquid water, conditions favourable for the assembly of complex organic molecules, and energy sources to sustain metabolism.” • Many other relevant factors, e.g. ‘Good Jupiters’ which shield planets from cometary impacts, shepherd orbits, even supply early planets with volatile components necessary for the introduction of life

  28. Planetary Atmospheres • E.g. Oxygen, Carbon Dioxide and Methane • Oxygen is only present on Earth thanks to early cyanobacteria and eventually photosynthesising plants • Without the right mixtures of liquids and gases a good CHZ is pretty irrelevant

  29. So...? • If what we’re looking for is another Earth, how far have we come?

  30. Planet Discoveries

  31. Planet Discoveries

  32. Finding Other Earths • May need to go below Earth’s mass when looking for life

  33. Finding Other Earths • Even if we find another Earth with life on it, would we be able to detect it? • Galileo Probe (left) searched Earth on a flyby for the ‘Sagan Criteria for Life’

  34. Finding other Earths • Red absorption - Plants • Oxygen absorption lines - Plants again • IR spectral lines - Methane • Narrowband modulated Radio - Technology

  35. Fomalhaut B First Visible Light Image of a Planet Orbiting Another Star • November 14th • 25 light years away • 3 MJ • 23 x Sun - Jupiter Distance • Ring like Kuiper-Belt

  36. Future Missions • Kepler-NASA’s 1st Earth Finder http://kepler.nasa.gov/ - 2009 • How are we proceeding? • SIM Planet Quest - next decade http://sim.jpl.nasa.gov/ • Terrestrial Planet Finder - maybe funded Atmospheric detections http://tpf.jpl.nasa.gov • CoRoT - Launched 2006 http://smsc.cnes.fr/COROT/ • Darwin - next decade www.esa.int/science/darwin

  37. Future Missions YOU! • How are we proceeding? Measurements of atmospheric signatures such as water, carbon dioxide and ozone (life) and sulfur dioxide and carbon monoxide (industrial)

  38. Websites and thanks • You again! • Lucas • Amy • Websites • www.ap.smu.ca/~lmorgan • http://www.astronomynovascotia.ca/ • APOD - http://antwrp.gsfc.nasa.gov/apod/astropix.html • NASA’s Planet Quest - http://planetquest.jpl.nasa.gov/ • Top 10 Exoplanets - http://www.space.com/scienceastronomy/extrasolar_planets.html • Exoplanet encyclopaedia - http://exoplanet.eu/

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