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Exozodiacal Dust Disks
- Not to be confused with debris disks
- Require interferometry to detect
- High levels (100-1000 zodi) even in >100 Myr systems
- Confound the detection of exoEarths
- Probe the structure of inner system
1 AU terrestrial planet with gap
0.5 – 1.5 AU warm dust disk 500K
0.1 – 0.5 AU hot dust disk > 1000K
Center A0 star @ 10 pcc
< 100K
100 AU
100-1400K
< 10 AU
HZ
Our disk is the most luminous object in SS after the Sun.
Earth would be a clump in the zodi at visible and IR [Kelsall+1998]
10-20 zodi would compromise exoEarth detection [Beichman+2006,Roberge+2012]
Interferometric, astrometric, direct, photometric, ...
exoEarth detection becomes challenging if exozodi level is ~20 zodis and clumpy [Defrère+SPIE 2012]
exoEarth detection is divided by factor of 2 for exozodi level increase of 10 [Stark+2014]
\(\geq\)10% of Gyr old MS stars may have enough exozodi dust to complicate exoEarth imaging [Kennedy & Wyatt 2013]
Resonant structures could indicate planets indirectly [Wyatt+1999]
Excess incoherent flux from dust creates challenges for design of coronographs and starshades
Nuñez, Scott, Mennesson 2017
NIR detections
Ertel+2014 merged FLUOR+PIONIER samples (n~125) reaching 0.25% precision
VLTI - PIONIER
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Rate decreases across spectral type
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Matches cold disk trend. Common origin?
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No correlation b/t hot dust and cold dust.*
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Different origin for hot and cold discs?
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Slight increase in exozodi detection with stellar age
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No correlation b/t exoplanets and exozodi.
HD 7788 shows variability
excess disappeared for a year
iot Psc
ups And
kap CrB
gam Ser
Absil+2013 detections
increased excess
new excess
![](https://s3.amazonaws.com/media-p.slid.es/uploads/709806/images/5784155/exozodi_variability_jouflu.jpg)
Scott+2015 revisits
1% CSE threshold
Sample of monitoring targets
You can't trust that a non-excess star will always remain one.
All 5 or more brackets, 3 cross-checked calibrators, targets and cals checked for binarity by interferometry AND speckle.
Scott dissertation 2015
Science/mission Goals
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Explore the apparent variability of known exozodis
- long-term monitoring
- clues to source and formation of the dust
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Expand strong exozodi sample
- leveraging LBTI and prior surveys
- from ~100 \(\rightarrow\) ~1000 objects
- Use spectral dispersion to resolve the thermal/scattered dilemma
- Risk mitigation for coronagraphy/starshade missions
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Target selection and characterization for mid/large missions (TESS, LUVOIR, HabEx, etc)
- exozodis likely to be dominant noise source
- Precision diameters and fundamental astrophysics
- Maintain a high angular resolution interferometric capability, unique to the Northern Hemisphere
Science gaps on Exoplanet program office list
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Science gap Number 4
- Planetary System Architecture
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Science gap Number 6
- Yield estimation for exoplanet direct imaging missions
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Science gap number 7
- Improve target lists and compilations of stellar parameters for exoplanet missions in operation or under study
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Science gap number 10
- Precursor surveys of direct image targets
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Science gap Number 11
- Understanding the abundance and distribution of exozodiacal dust
![](https://s3.amazonaws.com/media-p.slid.es/uploads/709806/images/3787010/viserr.png)
JouFLU upgrade paths
JouFLU prior limit
![](https://s3.amazonaws.com/media-p.slid.es/uploads/709806/images/5784363/pasted-from-clipboard.png)
JouFLU potential
JouFLU present
Getting to 5th mag could more than double the number of targets observable
CHARA AO is now coming online \(\rightarrow\) greatly improved obs efficiency
Goal is 1% excess detection at 5σ to mK < 5.
![](https://s3.amazonaws.com/media-p.slid.es/uploads/709806/images/5901173/IMG_20181205_145342.jpg)
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2019B - IO produced
2020A - install at CHARA
2020B - science observations begin
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ZBLAN IO chip
- losses ~0.4 db/cm
- get H band IO chip as "bonus"
- ~$50k
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v-groove and coupling optics (Ozoptics)
- ~$20k
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optomechanics
- ~$75k
- 2 or 4 beam H+K simultaneous
Saphira Selex detector
- will enable drastically better spectrally dispersed results
- $350k
Bertand/Nic
JPL internal funds
deck
By Nic Scott
deck
- 814