Lecture 1: Introduction & Methods 1.Introduction 2.Techniques for discovery & study 3.The NASA Kepler mission Planetary Systems Orbiting Diverse Stars

Where do we stand today? 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 … Planets Known to Orbit Other Stars:

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

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

The Planets of our Solar System

New types of planets: Hot Jupiters Super-Earths (Sasselov 2008)

Super-Earths Mass range: ~ Earth mass “Confusion region”

The super-Earths M-R diagram Fix one ratio: Earth-like Fe/Si max radius min radius H2OH2O Valencia, Sasselov, O’Connell (2007)

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

Techniques for discovery: Star-to-planet inequalities In light: (optical) to 10 7 (infrared) In mass: 10 5 to 10 3 In size: 10 2 to 10.

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

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

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

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

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

HD b: a Hot Jupiter

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

(from C. Lovis) HD 40307

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…

Summer 07: Ti:sapphire femtosecond laser comb Fall 2007: characterize with astro spectrograph 2008: develop high-rep rate comb for astro applications and demo on mountain-top 2009: Optimized system for 1 cm/s Doppler shift precision Harvard/Smithsonian/MIT astro-comb project Li et al. (2008, Nature, April)

Transits: A Method for Planet Discovery & Study

Transit Measurements

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

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

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

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

Illustration of high precision:  (R P )~3% Transits of exoplanets from Hubble: Brown et al. (2006) Light Flux Time TrES-1 HD Spot

Mass-Radius Diagram: Hot Jupiters Super-Earths (Sasselov 2008)

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

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

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

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

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

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

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

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!

HARPS-N Spectrometer Synergy with Kepler: Provide ability to reach RV amplitudes of about 10 cm /sec. Given P orb 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.

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…

Some Conclusions: 1.Extrasolar Earths - a worthy (and historic) goal: help us understand planet formation in general help us constrain pre-biotic chem / pathways to life 2.We now have the tools - to discover & study: Transits (Kepler), spectrograph (astro-comb)

Super-Earths Mass range: ~ Earth mass “Confusion region”

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

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