Extreme AOCoronagraph Science

with GPIJames R. Graham

UC, Berkeley

2

Outline

• ExAOC science impact– Direct vs. indirect planet searches

• GPI experimental design– Our knowledge of exoplanets defines AO

design– Trade studies

• ExAOC exoplanet surveys• Debris disks• Adjunct Science• Science Team

3

Why is High Contrast Useful?

• Exoplanet detection– Direct methods explore beyond 5 AU– Indirect methods give only M sin i, a & e

• Circumstellar disks– Proto-planetary & debris disks

• Fundamental stellar astrophysics– Large mass ratio main sequence binaries

• Stellar evolution—mass transfer & loss– Cataclysmic variables, symbiotic stars &

supergiants• Solar system

– Icy moons, Titan & asteroids

4

Direct Detection of Planets

• Voyager “family portrait” illustrates the impactof imaging– Solar system observations are the initial data point for

the theory of planet formation– Virtually all we know about exoplanets comes from

indirect Doppler methods: M sin i, a & e

5

Planet Searches• Doppler surveys have cataloged

about 150 planets– Indirect searches are limited by

Kepler’s third law: a = P2/3

• PJupiter = 11 years• PNeptune = 165 years

– Exo-Jupiters remain undetected– A survey of outer regions (a > 10

AU) is impractical using indirectmethods

• 1/r2 dimming of reflected lightrenders TPF-C insensitive toplanets in Neptune orbits– ExAO finds self-luminous planets

between 4–40 AU

CoDR p. 27

6

Architecture of Planetary Systems

• Only 5% of stars haveDoppler planets– Why isn’t it 15 to 50%?

• A diversity ofexoplanets…– Is the Solar System

typical?– ≤ 20% of the Solar

System’s orbital phasespace explored

• Do A, F or M stars haveplanets?

• How do planets form?– Core accretion vs.

gravitational collapse• New questions

– What is the origin ofdynamical diversity? CoDR p. 27

7

Imaging Beyond the Snowline

• Fast alternative to Doppler• Improved statistics

– 4–40 AU vs. 0.4–4 AU

• Find exoplanets at large(> 4AU) semimajor axes– Is the solar system is unique?– Sample beyond the snow line– Reveal if gravitational instability

forms planets (30–100 AU)– Uncover traces of planetary

migration

• Resolve M sin i ambiguity?– Mass from cooling curves

Mayer et al. 2002

20 AU

Qmin=1.7

Qmin=1.4

160 yr 350 yr

CoDR p. 29

8

Exoplanet Atmospheres

• Eclipses + Doppler data yield mass &radius for a few rare cases– Precision astrometry can be used to derive

masses—synergy with SIM (2010)• Direct detection of exoplanet light is the

key to unlocking chemical, structural, &evolutionary secrets

• Exoplanets are the “last frontier” ofclassical stellar atmospheres– Condensation of H2O and NH3

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Exoplanet Atmospheres

• Exoplanets occupya unique location in(log g, Teff ) phasespace– Over 5 Gyr a 1 MJ

exoplanet traverses thelocus of H2O and NH3cloud condensation

Jupiter

Teff [K]

Burrow

s Sudarsky &

Lunine 2003 ApJ 596 587

Galileo

NH3

CoDR p. 31

Mass

Age

0 200 400 600 800 1000

2.5

3.0

3.5

4.0

4.5

5.0

log 1

0 (g)

[cm

s-2]

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Detection of Cooling Planets

• Contrast requireddetect a exo-Jupiterin a 5 AU orbit in thevisible is 2 x 10-9

• Near-IR contrast istwo to three orders ofmagnitude less– Radiation escapes in

gaps in the CH4 and H2Oopacity at Y, J, H, & K

Burrow

s Sudarsky &

Hubeny 2004 A

pJ 609 407

CoDR p. 26

21 3 40.6 5 6

Wavelength µm

-16

-1

4

-12

-1

0

-8

-6

-4

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Experimental Design

• No simple metric identifies a suitable design– For example, minimize residual wavefront error

• This system works for a handful of bright, nearby stars• Could detect a few planets—if these stars host exoplanets• Reveals nothing about the statistical properties of exoplanets

• How do we maximize scientific productivity of ExAOC?– Large multi-dimensional trade space

• Contrast vs. limiting magnitude• Field of view (inner and outer working distances)• Observing wavelength• Spectral resolution• Speckle suppression

• Adopt number of detected planets as a metric– Define selection effects for exoplanet mass, age or spectral type

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Exoplanet Populations

CoDR p. 43

13

An Example• ExAOC configuration

– AO• r0 = 100 cm• 2500 Hz update rate• 13 cm subapertures

– R = 7 mag. limit– Coronagraph

• Ideal apodization– Science camera

• Broad band H• No speckle suppression

• Target sample– R < 7 mag.– 1703 field stars (< 50 pc)

Doppler

ExAOC

• Results– 110 exoplanets (6.5 % detection rate)– Semimajor axis distribution is

complementary to Doppler exoplanetsCoDR p. 46

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An Example• ExAOC configuration

– AO• r0 = 100 cm• 2500 Hz update rate• 13 cm subapertures

– R = 7 mag. limit– Coronagraph

• Ideal apodization– Science camera

• Broad band H• No speckle suppression

• Target sample– R < 7 mag.– 1703 field stars (< 50 pc) • Results

– 110 exoplanets (6.5 % detection rate)– Semimajor axis distribution is

complementary to Doppler exoplanets

ExAOC

Doppler

Astrometric

CoDR p. 46

15

Limiting Mag. & Detection Rate Trade

• Scientific success of Doppler surveys derive from the largenumber of planets detects—diversity is the rule– With ~ 100 planets trends are only just becoming apparent– Statistical trends only emerge from significant samples

• 3 properties × 5 bins per property × 4-σ counting statistics = 240 planets

6.5(5.4)

247(208)

3827< 8

10(10)

87(82)

833< 6

20(20)

13(13)

66< 4

50(25)

2(1)

4< 2

Guide starmagnitude (I )

No. of targetstars

No. of planetsdetected*

AO hit rate (%)*

* 18-cm sub-aperturesNumbers inparenthesisare for 12-cm

OCDD p. 25

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Observing Wavelength Trade• Clear dichotomy between observing wavelength/speckle suppression

– High performance near-IR system• Operates at ambient temperature (270 K)• Modest speckle suppression ( ×1/16–1/32)

– Low background/cryogenic L-prime system• No speckle suppression• Atmosphere & telescope background always dominate

Number of exoplanets

CoDRp. 48

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Speckles & Spectral Resolution

• Spectral resolution isnecessary for– Atmosphere diagnostics

• Teff and log(g)– Speckle suppression

• An IFU with λ/δλ ≈ 40, Δλ ≈20% supports– Classification of

atmospheres– > 10 Speckle suppression

for flat-spectrum sources– > 100 speckle suppression

for T dwarf spectrum

CoDR pp. 33 & 70

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ExAOC Field Star Survey

• Field survey with thebaseline CoDR system– Cerro Pachon seeing– 18 cm subapertures, I = 8

mag. limit– Adaptive modal gain control

2500 kHz maximum update– Apodized pupil Lyot

coronagraph– IFU withλ/δλ ≈ 40, Δλ ≈ 20% (

×16 speckle suppression)• No cut on stellar age• Exposure time

– 1 hour, 5-σ detectionthreshold

CoDR p. 55200 planets discovered

in field star survey

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Young Star Survey

• Young exoplanetsare bright

– Ca II H&K selectedsample (<2 Gyr)boosts detection rateto 36%

• Relax contrastdemands

– Probe further downthe exoplanet masssequence

N* = 170η = 36%

Fieldstar

exoplanets

Young associationexoplanets

OCDD p. 33

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Debris Disks• Gravitationally sculpted disks

provide key evidence forexoplanets

– Morphology of dust trapped inlibration points provides key tomasses and eccentricities ofexoplanets

– Surface brightness,color, phasefunction, and polarization indicatesquantity composition and grainsize distribution

• Fomalhaut debris disk F606W +F814W HST/ACS coronagraph

– µ ≈ 20 mag arc sec-2

– µ/µ0 ≈ 10-10

– High-mass exoplanet in a loweccentricity orbit

• Synergy with ALMA– Probe disjoint dust grain

populations

Kalas Graham & Clampin 2005Nature, 435, 1067

CoDR p. 36

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Debris Disks

• Only a handful ofdebris disks havebeen imaged inscattered light– Handful of high

spatial resolutionimages

– Few non-edge ondisks

AU Mic/Keck AO

Fitzgerald Kalas & Graham 2005

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Speckle Suppression for Debris Disks

• PSF subtraction– AU Mic/Keck AO

• Polarimetry– AU Mic/ACS polarimeter

CoDR p. 41

I Q U

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Dual Channel Polarimetry Simulations

• AU Mic/50– τ = 4 x 10-5

– θ = 90°, 70° & 30°• Edge-on disk is easily detected in Stokes I in 1 hour

– Progressively less visible in Stokes I in non edge-on configurations• Dual channel polarimetry reveals face-on disks

90°

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Dual Channel Polarimetry Simulations

• AU Mic/50– τ = 4 x 10-5

– θ = 90°, 70° & 30°• Edge-on disk is easily detected in Stokes I in 1 hour

– Progressively less visible in Stokes I in non edge-on configurations• Dual channel polarimetry reveals face-on disks

70°

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Dual Channel Polarimetry Simulations

• AU Mic/50– τ = 4 x 10-5

– θ = 90°, 70° & 30°• Edge-on disk is easily detected in Stokes I in 1 hour

– Progressively less visible in Stokes I in non edge-on configurations• Dual channel polarimetry reveals face-on disks

30°

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Adjunct Science

• General utility of highcontrast– Binaries

• Main sequence binaries• L & T dwarfs• White dwarf companions

– Evolved stars• Mass loss from red giants,

proto-planetary nebulae• Symbiotic stars

RY Scuti

– Solar system• Geomorphology of icy/rocky moons

– Broad opportunity for serendipity

R. Campbell

27

International Science Team

• Adam Burrows (UofA) Constrainingeffective temperatures and surfacegravities. Theoretical uncertainties inexoplanet detection.

• Eugene Chiang (UCB) Radiativetransfer & dynamics of debris disks

• René Doyon (UdM) Optimaldetection techniques for exoplanets

• James Graham (UCB) ProjectScientist. Coordinate science teamactivities. Monte Carlo trade-studytools. Traceability of sciencerequirements.

• Doug Johnstone (HIA)Interpretation of structure debrisdisks, including planetary & non-planetary signatures.

• Paul Kalas (UCB) Detection ofdisks & selection of debris disktarget stars

• James Larkin (UCLA) Multi-colorexoplanet detection.

• Bruce Macintosh (LLNL) PI Deliverestimates of integrated systemperformance.

• Franck Marchis (UCB) Solarsystem science.

• Geoff Marcy (UCB) Young starcatalogs. Algorithms formeasurement of orbital elements

• Ian Mclean (UCLA) Polarizationscience

• Ben Oppenheimer (AMNH)Detection & characterization ofexoplanets.

• Jenny Patience (Caltech) Catalogyoung associations & movinggroups. Age of field stars.

• Yanqin Wu (Toronto) Imprint ofplanets on disks. Vol 3

p. 21