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

Lecture 1: Introduction & Methods

1. Introduction2. Techniques for discovery & study3. 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

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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 ofplanets:

Hot Jupiters

Super-Earths

(Sasselov 2008)

Super-Earths

Mass range:~1 - 10 Earth mass

“Confusion region”

The super-Earths M-R diagram

Fix one ratio: Earth-like

Fe/Si

max radius

min

radius

H2O

Valencia, Sasselov, O’Connell (2007)

Super-Earths:excellent homesfor life

(Sasselov 2008)

Imag

e: S

.Cun

diff

Techniques for discovery: Star-to-planet inequalities

• In light: 1010 (optical) to 107 (infrared)

• In mass: 105 to 103

• In size: 102 to 10.

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Exoplanet discovery space:2007 & looking forward

Planned Kepler space mission:may detect Earth-like planets,

but measure only size, not mass

Pla

net

Mas

s

Direct Detection of Planets

• Direct detection is challenging because of the technicallimits oftelescopicobservations

Direct Detection of Planets

• Three planetsorbiting HR8799

…if star’s ageis < 300 Myr

(Marois et al. 2008)

Direct Detection of Planets

• There maybe more planets,but more obs neededto confirm even thisone.

(Kalas et al. 2008)

Radial Velocities (Doppler method): Discovery & Mass measurement

Radial velocities seenin star HD 209458 -the variation is dueto a planet that is lessmassive than Jupiter.

(Mazeh et al. 1999;Marcy et al. 2000)

HD 209458b: 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 Initiativewith Obs. Geneve on the William Herscheltelescope (WHT), Canary Islands

A HARPS clone,but for severalimprovements…

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Summer 07: Ti:sapphire femtosecond laser comb

Fall 2007: characterize with astro spectrograph

2008: develop high-rep ratecomb for astro applicationsand demo on mountain-top

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2009: Optimized system for1 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

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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 209458b: Dimming of light due to transit, observed with HST.

Brown, Charbonneau, Gilliland, Noyes, Burrows (2001)

Tells usDIRECTLY:Planet radius,

INDIRECTLY:Planet densityPlanet composition

Illustration of high precision: (RP)~3%

Transits of exoplanets from Hubble:

Brown et al. (2006)

Lig

ht

Flu

x

Time

TrES-1

HD 209458Spot

Mass-RadiusDiagram:

Hot Jupiters

Super-Earths

(Sasselov 2008)

A New super-Neptune: HAT-P-11b

Bak

os, N

oyes

, Pal

, Lat

ham

, Sas

selo

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(200

9)

Transit & eclipse of HD189733b

Heather Knutson & Dave Charbonneau (2007)

Spectrum for HD 189733bObtained by transit transmission & eclipse emission

Wavelength

Inve

rse

Res

idua

l Flu

x

New 2 m Spectrum for HD 189733b

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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 forsmall 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 Porb and phase from transit,this can translate to 10% massesin the Super-Earth and Earthsregime.

HARPS-N by Harvard - Geneva on the William Herschel telescope (WHT), Canary Isl.

HARPS-N Spectrometer on WHT

HARPS-NEF: Harvard Origins Initiativewith Obs. Geneve on the William Herscheltelescope (WHT), Canary Islands

A HARPS clone,but for severalimprovements…

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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:~1 - 10 Earth mass

“Confusion region”

Super-Earths as proxies for EarthHow to distinguish mini-Neptune from super-Earth:

< Three types of atmospheres

(Miller-Ricci, Seager,Sasselov 2008)

Super-Earths as proxies for EarthHow to distinguish mini-Neptune from super-Earth:

(Mill

er-R

icci

, Sea

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