Clio: 3-5 m planet-finding AO camera

Ari Heinze (Steward Observatory)

Collaborators:P. Hinz (Steward), S. Sivanandam (Steward),

M. Freed (Optical Sciences), A. Breuninger (Steward)

First planet

3-5 m Window

• High Background– Warm Telescope– Variable and High Sky Flux

• Atmospheric Throughput• High Duty Cycle Readout• Large Well-depth Detector• Better contrast ratios• M-band bump in planets only

weakly dependent on age• Observing catalogue

includes nearby moderate age stars

• Better AO correction

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Near/Thermal IR Spectra of known extrasolar giant planets around G-type stars. Mass range from 1-10 MJup. M-band bump present irrespective of age and mass, though near-IR flux decreases steeply with age. (Burrows et al. 2004)

Clio Design

• Diffraction-limited imaging from H through M-bands• 3 imaging modes: f/35 (H and K-bands), f/20 (L and

M-bands), and pupil imaging (for alignment of cold-stops) modes

• 320256 large well-depth, high throughput InSb array optimized for 3-5 m imaging (Indigo Systems Inc.)

• Cooled optics (77K), baffling, and cold stops to minimize instrument thermal background

• Coronographic option built in (have ability to add field and pupil stops and PSF shaping wave plates)

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Clio Schematic

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Schematic of Clio in f/20 mode with ray trace.

Detector Performance

Bias Voltage 4.0V

Temperature 56 K

Pixel Rate 400 kHz

Duty Cycle ~ 90%

Frame Rate 20 Hz

QE3-5 m 0.9

Well Depth 3.3106 e-

Dark Current 3.0105 e-/s

Read Noise 800 e-

Gain 82-94 e-/DN

Linearity 1%Detector Characteristics

Detector Noise Map

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Observing Strategy

• To remove high sky background:– Nod the telescope a few arcseconds after each exposure and close

AO loop– Subtract nod pairs

• To improve duty cycle– Coadd batches for ~20 images for every exposure

• To improve sensitivity– Integrate in the L’ and M-band until sky flux fills ~1/2 of full well

• Typical integrations: 100 ms (M-band); 1500 ms (L’-band)

– Sky background-limited and detector noise is negligible

• To mitigate long-lived speckles– Keep instrument derotator fixed allowing the sky to rotate– Rotate images by the parallactic angle to correct orientation

during processing– Static speckles stay fixed on chip and are blurred out by rotation

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On-sky Performance• Reach quoted 10background-

limited detection values at separations greater than 1.5” from the central star (after PSF subtraction and unsharp mask)

• L’ ~ detect 5 Mjup 0.5 Gyr old planet at 10 pc

• M ~ detect 10 Mjup 0.5 Gyr old planet at 10 pc

• Have better L’ sensitivity– Focus initial search in L’– M-band follow up observations to

obtain color and establish nature of source

• Very stable PSF– Good subtraction of PSF, better

contrast

FOV 15.5”12.4”

Plate Scale 0.0496”/pix

ThroughputL’ 0.67

ThroughputM 0.42

Emissivity* ~10%

10 L’ (1 hr) 16.3 mag

10M (1 hr) 13.5 mag

PSFs of 5 different L’ exposures

Clio Observational Parameters

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S

T

M

Vega in M-band

Dust model and predicted planet position (Wilner et al. 2002)

Clio 672 s M-band image (unsharp masked)

First Light Observations (ApJ, accepted)SPIE 2006 - Clio - Page 9

Vega Sensitivity

1 arcsecSeparation (arcsec)Com

pan

ion

mass lim

it (

5 s

igm

a)

Macintosh et al. (ApJ 594, 538)using Keck atK-band

Limit from 5 minute observation at M band

Expected Planet?

Metchev et al. (ApJ 582, 1102)using Palomar at H-band

10 Mjup fake planet at 20 AU

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Vega Planet Sensitivity Comparison Vega Fake Planet

GJ450 in L’-band

2 arcsec

Stellar properties:• M dwarf• 1 Gyr (X-ray)• 9 pc

Observation:• 5355 s L’ exposure• No detection

Sensitivity Test:• Monte Carlo simulation

– 10 planets• Blind test

– Recovered all planets reliably

GJ450 Exposure with fake 10 planets

Nod artifact

GJ450 Monte-Carlo Planets

Sep (arcsec) L’ mag Mass (MJ)

0.51 12.53 28.08

0.56 13.32 20.55

0.95 15.35 9.85

1.14 15.6 8.96

1.27 15.96 7.66

1.58 16.06 7.40

1.90 16.51 6.05

2.50 16.59 5.89

2.91 16.38 6.44

2.98 16.6 5.87

3.71 16.51 6.05

3.90 16.59 5.88

3.93 16.62 5.83

5.02 16.49 6.11

6.52 16.43 6.29

6.53 16.27 6.782.69 16.57 5.91

Continued

GJ450 Sensitivity

6 Mjup

Backgroundlimited

PSF subtracted

Contrast Ratio in L’-band

10 Planet Mass Sensitivity

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PSF Suppression

• PSF sidelobes are over 7 magnitudes fainter at 3 λ/D away• The pattern is stable and can be reliably subtracted off to reach the

limit of the sky background• PSF suppression is easier at M-band where Strehls are typically 90%

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Science Programs

• 6 pc M dwarf search [observed 4 stars]• M through F star search (emphasis on solar-

type stars) [observed 20 of 50 stars]• A-type star search [this trimester]• White dwarf search [this trimester]• Vega search [observed twice]• T-dwarf photometry [this trimester]

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Vega, M-band, 2850 sec (April)

Vega, M-band, ~1hr (June)

ξ Boo, L’, ~1 hr

ξ Boo, M, ~1 hr

BD+60 1417, L’, ~1hr

BD+60 1417, L’, ~1hr

BD+60 1417, L’, ~1hr

BD+60 1417, Ks, ~1hr

Stay tuned…

The first direct image of a mature extrasolar planet orbiting a normal star may be only months away… And may well happen at the MMT.

Design SimulationsMONTE CARLO SIMULATIONSTake spectra of 100 Myr - 5 Gyr

old planets, and consider: • Instrument Throughput• Atmosphere• Sky Background• Telescope Emissivity (10%)• Strehl Ratio• Planet Photon Noise• Detector Dark Current/Read

Noise

Best Filter Bandpass: M-band

Best Bandpass S/N Plot. (Freed et al. 2004)

Outline

• Why 3-5 m?• Clio Design• Detector Performance• Clio On-sky Performance• Latest Scientific Results• Planet-finding Sensitivities• Science Program

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