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Buscando a vida fora da Terra: Além do Sistema Solar

AGA 0316 AULA 16. Buscando a vida fora da Terra: Além do Sistema Solar. Extrasolar planets. Extrasolar planets=Exoplanets= planets around stars other then the Sun Planets are the environments for the origin and evolution of life.

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Buscando a vida fora da Terra: Além do Sistema Solar

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  1. AGA 0316 AULA 16 Buscando a vida fora da Terra:Além do Sistema Solar

  2. Extrasolar planets • Extrasolar planets=Exoplanets= planets around stars other then the Sun • Planets are the environments for the origin and evolution of life. • Giordano Bruno: “There are countless suns and earths all rotating around their suns in exactly the same way as the seven planets of our system..” (1584) • First confirmed planet – 51 Pegasi on October 1995 by Mayor and Queloz (1995)

  3. Which type of star?

  4. Exoplanets(Oct 2013: ~ 1040 DESCOBERTOS)

  5. Hertzsprung-Russell (HR) Diagram http://observe.arc.nasa.gov/nasa/space/stellardeath/stellardeath_1ai.html

  6. Prospects for finding habitable planets • Best candidates are F, G, and early K-type stars, i.e., stars not too different from the Sun • Early-type stars (blue stars) • High UV fluxes • Short main sequence lifetimes • Late-type stars (red dwarfs) – M-class • Tidal locking • Lots of flares

  7. 59 planets 11 planets9 systems 1 multiple 8 planets7 systems 1 multiple 1 planet 321 planets 274 systems 33 multiples 7 planets 4 systems 2 multiple Extra-Solar Planets Catalog(http://exoplanet.eu/catalog.php).Last update: 30/05/2009

  8. How to detect exoplanets? 1) Direct detection 2) Astrometry 3) Microlensing 4) Velocitometry 5) Transits

  9. Methods for detection of Exoplanets 1) Astrometry: changing on spatial star position  exoplanet detection Inconclusive and marginal. 2) Direct (imaging) detection: only forBIG and sufficiently distant planets: weak contrast Contrast Star-Planet: > 100,000,000 for a Jupiter-like planet in the Visible ~ 100,000 for a Jupiter-like planet in the IR  interferometric/coronagraphic techniques

  10. Direct detection: planet around starFomalhaut(25 l-y from the Sun)

  11. Other examples of direct detection AB Pic Beta Pic Hubble image of possible exoplanet TMR-1C (NASA)

  12. Four planets around HR 7899 (Palomar)

  13. Methods for the detection of exoplanets 3) Gravitational microlensing (Einstein effect) Some dozens exoplanets discovered with this method (Mpl ~Atm) Planet OB05390

  14. Methods for the detection of exoplanets 4) Velocitometry: stellar radial velocity variations   presence of unseen body Many hundred exoplanets discovered by this method Radial velocity variations + Kepler's 3rd law  Mpl; Porb

  15. PROBLEM with the velocitometry method Described by Newton's law: F = G x Mstar x Mplanet distância2 ►► BIAS: detected mainly planets more massives&nearer to their hosts stars

  16. Detection by velocitometry method: the system of Gliese 581 Discovery of 3 planets: April, 2007(Udry et al.) 2009-2012: discovery of other planets, not all confirmed yet Udry et al: planet d at ZH? ? 

  17. GLIESE 581 PLANETARY SYSTEM? No atmosphere

  18. Methods for the detection of exoplanets 5) Transit method: detection of the tiny eclipse caused by the passage (transit) of a planet in front of its star.  Rpl ; Porb Transit of VENUS June 6, 2012

  19. Method of planetary Transits

  20. d d  Rpl2 ⁄ Rstar2 CoRoT star Porb = interval between 2 eclipses

  21. Satellites observing transits CoRoT KEPLER NASA Europe + Brazil

  22. KEPLER and CoRoT have found tens of multiplanetary systems The moment of the eclipse by one planet is perturbed by the presence of other planet(s)

  23. The launch of CoRoT (Dec 26th, 2006) (launch no. 1735 of SOYUZ without a failure)

  24. Exoplanets: methods of detection

  25. The Habitable Zone (HZ) Definition: region around a star where the temperature on the surface of an eventual planet or moon can afford the presence of liquid water. Conditions: the position and width of the HZ depends on the presence and composition of the atmosphere (greenhouse effect - GE). On EARTH: GE raises temperature by ~32 °C

  26. Exoplanets & Astrobiology The Habitable Zone (HZ): liquid water

  27. Outra possibilidade interessante: Rocky Moon orbiting a Jupiter in HZ There are many Jupiters discovered in HZ

  28. Planets and Astrobiology Most favorable cases: F-G-K stars(similar to the Sun): stabilityand evolution time Hot (blue) stars: too much UV radiation and shortMSevolution time Cold (red dwarf) stars: energetic explosions (flares) and tidal lock problem. But: 85% of stars in Milky Way are red dwarfs (> 100 billion many planets)

  29. THE EXOPLANET ZOO Number of planets in the Milky Way: ~ 400 billion Number of Earth-like planets in the Milky Way: ~ 100 billion

  30. NUPESC Ago 2012 31

  31. The KEPLER + CoRoT legacy (www.seti-setr.org)

  32. Period ~20hs Mass  7 MEarth CoRoT 7-b, the first planet discovered with Earth-like density

  33. =CoRoT 7b NUPESC Ago 2012 37

  34. How Will We Know A Planet Supports Life? Look for evidence of oxygen Look for liquid water Look for signs of biological activity (methane) Analyze the reflected light from the planet to see if the planet has an atmosphere And Rule Out Other Explanations? 17

  35. NIMS Data for the Earth (from Galileo) (‘A’ band) *But credit Toby Owen for pointing this out (1980) Sagan et al. (1993)*

  36. NIMS data in the near-IR • Simultaneous presence of O2 and a reduced gas (CH4 or N2O) is the best evidence for life *Credit Joshua Lederburg and James Lovelock for the idea (1964) Sagan et al. (1993)*

  37. Wavelength

  38. Thermal IR spectra Source: R. Hanel, Goddard Space Flight Center

  39. Possibility of remote detection of life Explore the contrast star/planet in thermal IR (Des Marais et al. 2002, Segura et al. 2003) Window at 8-12 μ m: Tsurface Porto de Melo et al., Astrobiology, 2006 > 106 H2O 6.3 μm + 12 μm band CH4 7.7 μm O3 9.6 μm CO2 15 μm

  40. Darwin (ESA) 2022?

  41. Darwin summary • ESA’s Darwin mission • may eventually be able to locate Earth-sized planets around other stars and take either visible or thermal-IR spectra of their atmospheres • O2 (or O3) andCH4have absorption bands in both wavelength regions that may be used as potential indicators of extraterrestrial life But, • We need other bio-indicators for reduced, early-Earth type atmospheres

  42. Navigator Program Cancelled Delayed 3 yrs Cancelled Overcost An Integrated Program of Planet Finding Science (NASA) 1 KEPLER Survey of distant stars for Earths Optical signs of habitable worlds KECK TPF-C Survey of nearby stars for dust and giant planets Mid-infrared signs of habitable worlds SIM Masses and orbits of large terrestrial planets TPF-I ARE THERE OTHER HABITABLE WORLDS? LBTI JWST PLANET CHARACTERIZATION • Planet chemistry in visible and infrared • Presence of water • Radius • Surface gravity and temperature • Atmospheric conditions • Biomarkers ARE THERE OTHER SOLAR SYSTEMS LIKE OUR OWN? • Young Jupiters • Transit Follow-up • Debris Disks PLANET DETECTION • Nearby giant planets • Young, hot Jupiter's approved 2005 2010 2015 2020 2025

  43. OUTRAS MISSÕES PROGRAMADAS PARA 2020-2030 SOBRE EXOPLANETAS (NASA, ESA) PLATO (ESA), ECHO (ESA), TESS, SIM, JWST ALMA (Atacama Large Milimmeter Array), MATISSE (espectro-interferômetro, IV), etc...

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