1. Exoplanet transits with MIRI
P.-O. Lagage (CEA – Saclay)
On behalf of
MIRI EC exoplanet working group
(present here Jeroen Bouwman and Daniel Dicken)
+ Tom Greene 1

2. MIRI is a 50%-50% Europe-US share project
PI’s G. Wright (ATC, UK) , G. Rieke (Arizona University)
A 5 to 28 μm imager and spectrometer
(The only JWST instrument in this l range)
Opto mechanics + tests
in Europe by a nationally
funded consortium of
European Institutes
Detector and cryocooler In US (JPL)
Unlike the other JWST instruments, MIRI has to be cooled to 7K
 Dedicated cryocooler 2

3. 5 – 27 microns  BB peak emission with T 600 K - 165 K.
MIRI best suited to detect the emission of “cool” objects.
Froim Tinetti et al. 2013 3

4. Main molecules have bands in the Mid-IR
From Tinetti et al. AAR 2013 4

5. Observing modes
slit
A single mechanism for
the imager of MIRI 5

6. When we started MIRI, last century …
Only radial velocity
No direct imaging
Detection; No transit 6

7. : slitless spectroscopic mode
New mode for exoplanet
: slitless spectroscopic mode
Slitless for photometric precision;
+ reading only a sub array (64*512 over the 1k*1k  minimum tint=0.165 s
 to limit saturation to K magnitude star of about 5.5
(HD just at the limit)
Probably the observational
mode the most used for
exoplanet transit 7

8. LRS optical design Entrance Based on a double prism
Dubreuil et al. 2003 8

9. First detection expected
Spectral range…
Spectral range requirement : 5 – 10 microns
As built: extended on BOTH side
NH3 lines:
10.33 and microns
Important lines
to probe T,…
First detection expected
from JWST
CO, CO2
PH3 lines … 9

10. Spectral resolution
depends on l
S. Kendrew et al. PASP 2015 10

11. LRS Spectra simulator
4 mm
10 mm
14 mm
S. Kendrew et al. PASP 2015 11

12. Saturation due to this part of the spectrum
(SED star, Resolution, PSF) 12

13. Spectrum folding Some short wavelegth mixed with the 5-5.5 microns
Small effect under quantitative analysis 13

14. Difficult observations
Relatively safe down to 100 ppm but aims at going down tp 10 pm
Example of subtil effects : spectrometer franging and jitter (effect below 100 ppm)
S. Kendrew et al. PASP 2015 14

15. The MIRI Focal Plane Modules
M. Ressler et al. : “The Mid-Infrared Instrument for the JWST : VIII The MIRI Focal Plane System, PASP, 2015 in press 15

16. MIRI detector array properties
M. Ressler et al. : “The Mid-Infrared Instrument for the JWST : VIII The MIRI Focal Plane System, PASP, 2015 in press 16

17. Detectors drifts, latents under deep study (see Dan Dicken here ..)
Representative detector tests for exoplanets observations
to be done at JPL next year (Mike Ressler et al.) 17

18. Medium Resolution Spectrometer
An Integral Field Unit Spectrometer
Advantages :
gives access to the long wavelengths (13 – 28 mm)
medium resolution (between
Desadvantages:
time consuming :
3 settings to get the full spectra
low photon – electron conversion: about 0.1
franges + jitter could limit the precision
(more information on the jitter needed
to make averages…) 18

19. Medium Resolution Spectrometer
An Integral Field Unit Spectrometer
2 channels
M. Wells et al.: PASP, 2015 in press 19

20. Three settings to get a full spectra
Martyn Wells et al. PASP 2015 20

21. Very little in the mid-IR so far !
Not by lack of interest but by lack of facilities
For direct imaged exoplanet: nothing
(Spitzer not the angular resolution and ground-based lack of sensitivity)!
For transisting planets, spectra of only 2 giant bright exoplanets :
HD b, HD (cold Spitzer)
+ photometry of a few dozens of transiting exoplanets
expecially at 3.6 and 4.8 microns (warm Spitzer) 21

22. S x 50 To JWST Telescope size : 85 cm
From Spitzer
S x 50
Telescope size : 85 cm
Amazing relative photometric precision
(better than 10-4) for an observatory not
Conceived for exoplanets observations
Telescope size 660 cm
At the same photometric precision
going from photometry (R=2) with SPITZER
to spectroscopy with JWST
Need enhanced photometric precision

23. Which kind of exoplanets to be observed with MIRI ?
Transiting exoplanets: Down to super Earth
Giant planet
warm Neptune--‐
mass planet
sub-Neptune
small planets
yet to be discovered
(K2, TESS)
Only 2 spectra in the mid IR
obtained with cold Spitzer
Terra quite incognita
Terra incognita
Terra super incognita
Ricker et al. 2014 23

24. Example of use of the imager,…
Particularly interesting for broad features as CO2 24

25. 25

26. Example of use of the LRS
Detection of C2H2 and HCN in carbon rich geant exoplanets
Poster by Marco Rochetto, Olivia Venot, Pierre-Olivier Lagage et al.
1) Models (1D)
2) MIRI simulations
(no detector effect so far)
3) Retrieval (TAUREX) 26

27. O3 in Earth like planet around M dwarf
J. Barstow et al. 2015 27

28. SuperEarth with mineral atmosphere : Si0 band at 10 microns
Y. Ito et al ApJ 2015 28

29. Dust features in the mid-IR29

30. Are we ready ? From an instrumental performances, I would say
Not fully yet
But we are working hard to be 30

31. In any case we should be ready to
get surprises once JWST is in operation
both in intrumental terms (stability,…)
and in terms of data science contains, especially
with MIRI, which is really opening up the field of exoplanet atmosphere
characterization from mid-IR observations 31

32. For more detailed information about MIRI capabilities:
Ten papers about MIRI in PASP 2015
I: Introduction, G. H. Rieke, G. S. Wright, T. Boker et al.
II: Design and Build, G. S. Wright , D. Wright, G. B. Goodson, et al.
III: MIRIM, the MIRI Imager, P. Bouchet, M. Gacia Marin, P.O. Lagage et al.
IV: The Low Resolution Spectrometer, S. Kendrew, S. Scheithauer, P. Bouchet et al.
V: Predicted Performance of the MIRI Coronagraphs A. Boccaletti, P.O. Lagage, P. Baudoz et al.
VI:The Medium Resolution Spectrometer, Martyn Wells, J.-W. Pel, A. Glasse et al.
VII: The MIRI Detectors, G. H. Rieke, M. E. Ressler, J. E. Morrison et al.
VIII: The MIRI Focal Plane System, M. E. Ressler, K. G. Sukhatme, B. R. Franklin et al.
IX: Predicted Sensitivity, A. Glasse, G. H. Rieke, E. Bauwens et al.
X: Operations and Data Reduction, K. D. Gordon, C. H. Chen, R. E. Anderson et al. 32

33. Thank you for your attention33

34. Exoplanet Atmosphere studies
To contrain internal structure of exoplanets,
To contrain exoplanet formation and migration
from spectroscopic observations  C/O ratio; metallicity …
To study the atmosphere of exo-planets by itself and test atmospheric
models, circulation models, climate models in new regime
Atmosphere structure
Temperature/pressure profiles in atmospheres.
Origin of high altitude temperature inversions?
Atmosphere dynamics, climate
From phase curves,
from ingress, egress precise measurements  « 2D maps » possible;
Variability
Majeau et al. 2014 34

35. 35

36. 36

37. A 4 microns window ? 37