O. Absil & C. Eiroa

with inputs from

A. Roberge, D. Defrère, C. Beichman, W. Danchi, J.-C. Augereau, etc.

P3 panel: exozodiacal disks

We all live in a debris disk!Asteroid collisionsComet outgassing

Dust is luminous (much more than the Earth)Dust is expected in any planetary system

Dust in planetary systems

Kuiper belt: 40 K, 50 AU Zodiacal disk: 300 K, 1 AU

Observations

Dust not uniformly distributed

Simulations

Earth at 1 AU

Stark & Kuchner 2008

10-100 zodi tolerable for closest targetsAsymmetries need thorough investigation

The exozodi issue: visible imaging

2m

4m

6m

8m

12m

Shot noise: 100 zodi tolerable in averagePreserves 75% of mission outcome

Asymmetries: ~10 zodi tolerable

The exozodi issue: IR interferometry

If Solar system is the rule, “Earth explorer” could just skip unsuitable systemsCan afford to loose some timeEZs interesting on their own

What if EZ mode is around 10 zodi? 100 zodi? Is the distribution log-normal at all? Bimodal?

But ... do we really care?

100 zodi?

10 zodi?

< 1 zodi?

Bad systems

1001010.10.01 1000

What we know: exo-Kuiper beltsDetected since 1984

IRAS, ISO, SpitzerSensitivity ~ 100 ×

solarHerschel

Down to 1 × solarActual distribution

will soon be known for the cold parts

What about warm parts?

100 × solar

Bryden et al. 2006

What we want to know: exozodisMid-infrared most

suitedPhotometry

Spitzer: IRS, MIPSImaging

10-m telescopes, (JWST)

InterferometryKeck Nuller, VLTI/MIDI

Near-infrared can helpInterferometry

CHARA/FLUOR, VLTI/VINCI

Exozodis: where we standIRS, MIPS

1000 zodi at 3-σLarge sample~2% of systems

Keck Interferometer Nuller300 zodi at 3-σSmall sample (on-going)

K-band interferometry 1000 zodi at 3-σSmall sample (on-going)~20% of MS stars with

large amount of hot dust??EZs ≠ from solar zodi??

1001010.10.01

KIN300 zodi

1000

Solution #1Use models to connect Kuiper belts with

exozodisProblem: planetary system architecture

matters!Solution #2

Survey exozodis to build histogramWhat should be the goal sensitivity?

Probably around 30 zodi (3-σ)

Solution #3Characterise exozodis around all identified

targets(need to wait for SIM or RV detections, and to

reach 10 zodi)

What needs to be done?

What does it take?LBTI

Expect ~30 zodi at 3-σ

Survey starting > 2012

60 targets: sufficient?Other possible nullers

ALADDIN Balloon FKSI/Pegase

Other instruments Small coronagraphs:

need to be investigated

Invest in modellingProbability distribution (log-normal? bimodal?

other?)How deep is enough? 30 zodi? Asymmetries: better predictions needed!

Invest in LBTICould greatly reduce the exozodi problem if it

lives up to the expectationsSupport development of other exozodi finders

ALADDIN, balloon, FKSI (share the same payload)Small coronagraphs?

Conclusions / recommendations