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Lecture 1: Introduction & Methods

Planetary Systems Orbiting Diverse Stars. Lecture 1: Introduction & Methods. Introduction Techniques for discovery & study The NASA Kepler mission. Where do we stand today?. Planets Known to Orbit Other Stars:. Total : 330+ ( 31 systems) discovered to-date Statistics:

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Lecture 1: Introduction & Methods

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  1. Planetary Systems Orbiting Diverse Stars Lecture 1: Introduction & Methods Introduction Techniques for discovery & study The NASA Kepler mission

  2. Where do we stand today? Planets Known to Orbit Other Stars: • Total: 330+ ( 31 systems) discovered to-date • Statistics: • Gas giant planets, like Jupiter & Saturn, exist around >12% of stars (Marcy et al.); • Lower-mass planets (Super-Earths, ~12 known to-date) are more common (Mayor et al.); • No Earth-like planets yet …

  3. Small stars, Brown dwarfs, & planets Evolution of luminosity with time for different masses Burrows 2000)

  4. Properties of planets & small stars Models: Baraffe et al. four different ages: 0.5, 1, 3, & 5 Gyr Red: Pont et al. (2005) OGLE-TR-122

  5. The Planets of our Solar System

  6. New types ofplanets: Hot Jupiters Super-Earths (Sasselov 2008)

  7. Super-Earths “Confusion region” Mass range: ~1 - 10 Earth mass

  8. The super-Earths M-R diagram max radius H2O min radius Fix one ratio: Earth-like Fe/Si Valencia, Sasselov, O’Connell (2007)

  9. Super-Earths: excellent homes for life Image: S.Cundiff (Sasselov 2008)

  10. Techniques for discovery: Star-to-planet inequalities • In light: 1010 (optical) to 107 (infrared) • In mass: 105 to 103 • In size: 102 to 10.

  11. Exoplanet discovery space:2007 & looking forward Planet Mass Planned Kepler space mission:may detect Earth-like planets,but measure only size, not mass

  12. Direct Detection of Planets • Direct detection is challenging because of the technical limits of telescopic observations

  13. Direct Detection of Planets • Three planets orbiting HR8799 …if star’s age is < 300 Myr (Marois et al. 2008)

  14. Direct Detection of Planets • There may be more planets, but more obs needed to confirm even this one. (Kalas et al. 2008)

  15. Radial Velocities (Doppler method): Discovery & Mass measurement Radial velocities seen in star HD 209458 - the variation is due to a planet that is less massive than Jupiter. (Mazeh et al. 1999; Marcy et al. 2000)

  16. HD 209458b: a Hot Jupiter

  17. 1 m/s The HARPS planet-search program ESO 3.6 – La Silla - Geneva Observatory - Physikalisches Institut, Bern - Haute-Provence Observatory - Service d’Aeronomie, Paris - ESO

  18. (from C. Lovis) HD 40307

  19. HARPS-N Spectrometer on WHT HARPS-NEF: Harvard Origins Initiative with Obs. Geneve on the William Herschel telescope (WHT), Canary Islands A HARPS clone, but for several improvements…

  20. Harvard/Smithsonian/MIT astro-comb project Summer 07: Ti:sapphire femtosecond laser comb 2008: develop high-rep ratecomb for astro applicationsand demo on mountain-top 2009: Optimized system for1 cm/s Doppler shift precision Fall 2007: characterize with astro spectrograph Li et al. (2008, Nature, April)

  21. Transits: A Method for Planet Discovery & Study

  22. TransitMeasurements

  23. Transit & eclipse of HD189733b Heather Knutson & Dave Charbonneau (2007)

  24. OGLE-TR-113b Doppler Shift Transit Light Curve Konacki, Torres, Sasselov, Jha (2004)

  25. The HAT Network: FLWO Mt.Hopkins Arizona … and Hawaii Mauna Kea We have discovered >11 new planets with it in 2 years. (Bakos et al. 2009)

  26. What can we learn from transiting extrasolar planets HD 209458b: Dimming of light due to transit, observed with HST. Tells us DIRECTLY: Planet radius, INDIRECTLY: Planet density Planet composition Brown, Charbonneau, Gilliland, Noyes, Burrows (2001)

  27. Transits of exoplanets from Hubble: Illustration of high precision: s(RP)~3% TrES-1 HD 209458 Spot Light Flux Time Brown et al. (2006)

  28. Mass-RadiusDiagram: Hot Jupiters Super-Earths (Sasselov 2008)

  29. A New super-Neptune: HAT-P-11b Bakos, Noyes, Pal, Latham, Sasselov et al. (2009)

  30. Transit & eclipse of HD189733b Heather Knutson & Dave Charbonneau (2007)

  31. Spectrum for HD 189733b Obtained by transit transmission & eclipse emission Inverse Residual Flux Wavelength

  32. New 2 m Spectrum for HD 189733b (Swain et al. 2008)

  33. NASA Kepler mission: transit search for planets Cygnus / Lyra (RA=19h23m, Dec=44.5d)

  34. Completing the Copernican Revolution:the discovery of “New Earth” NASA Mission - Mar. 2009

  35. Kepler is ready to launch: Mar. 5, 2009 Kepler expected yields: ~ 500 super-Earths, ~ 50 Earth analogs; (5-10% good radii) Assembly at Ball Aerospace

  36. The “PROBLEM” with KEPLER: not able to get data on masses for small planets - reflex amplitudes will be less than 30 cm /sec. • SOLUTION: • build a novel Doppler instrument • to fit on a large telescope. • Use it to measure masses, and hence mean densities for KEPLER’s best candidate Earths & super-Earths!

  37. HARPS-N Spectrometer Synergy with Kepler: Provide ability to reach RV amplitudes of about 10 cm /sec. Given Porb and phase from transit, this can translate to 10% masses in the Super-Earth and Earths regime. HARPS-N by Harvard - Geneva on the William Herschel telescope (WHT), Canary Isl.

  38. HARPS-N Spectrometer on WHT HARPS-NEF: Harvard Origins Initiative with Obs. Geneve on the William Herschel telescope (WHT), Canary Islands A HARPS clone, but for several improvements…

  39. Some Conclusions: • Extrasolar Earths - a worthy (and historic) goal: • help us understand planet formation in general • help us constrain pre-biotic chem / pathways to life • We now have the tools - to discover & study: • Transits (Kepler), spectrograph (astro-comb)

  40. Super-Earths “Confusion region” Mass range: ~1 - 10 Earth mass

  41. Super-Earths as proxies for Earth How to distinguish mini-Neptune from super-Earth: < Three types of atmospheres (Miller-Ricci, Seager, Sasselov 2008)

  42. Super-Earths as proxies for Earth How to distinguish mini-Neptune from super-Earth: (Miller-Ricci, Seager, Sasselov 2008)

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