1A. Boccaletti

Pasadena, Sept. 28-29th

Imaging EGPs with JWST/MIRI and VLT/SPHERE

valuable experiences for TPF-C

A. Boccaletti, P. BaudozD. Rouan + coronagraphic team@ Paris Observatory

2A. Boccaletti

Pasadena, Sept. 28-29th

MIRI coronagraph conceptmonochromatic coronagraphs

4 masks in focal plane

BB temperature

un

der

sam

ple

d

NH3 abundance

MIRI is not optimized for Coronagraphy (because of JWST …)

we are looking at 10-4 - 10-5 contrast ratio

… but still of interest in the current context and given the timescale of future missions

[Boccaletti et al., Baudoz et al.]

3A. Boccaletti

Pasadena, Sept. 28-29th

MIRI Performance (examples)Evaluate sensitivity to : - pupil shear

- pointing offset- defocus

Develop a model : - telescope & aberrations- planetary spectra

0

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0 1 2 3 4 5 6 7 8 9 10

pupil shift (% of diameter)

Attenuation factor

total rejection

max attenuation

differential pointing : 0masdifferential pointing : 5masdifferential pointing : 10mas

differential pointing : 15mas

4A. Boccaletti

Pasadena, Sept. 28-29th

SPHERE- 2nd generation instrument at VLT (ESO) - 2010 [Beuzit et al.]- stands for Spectro-Polarimetric High contrast Exoplanet REsearch- study of EGPs around nearby stars and in young associations down to 0.5-1MJ

- combination of 3 instruments - IR camera Dual Band Imaging IRDIS- IR Integral Field Spectrograph IFS- Vis. camera Dual Polarisation Imaging ZIMPOL

- AO high order correction (40x40 actuators), high stability, static error compensation - IR coronagraphs :

- Lyot- apodized Lyot - achromatic phase masks

SPHERE capabilities rely on differential imaging (spectral or polarimetric)

5A. Boccaletti

Pasadena, Sept. 28-29th

SPHERE Simulatorbased on CAOS [Carbillet et al.]

Developed for a full system analysis, not only coronagraphs

1. put specs. on the system :- AO related parameters- PSD and amplitude of phase aberrations upstream the coronagraph- pointing alignment (accuracy, reproducibility)- pupil centering (accuracy, reproducibility)- focus stability- chromatic aberrations upstream/downstream coronagraph- comparison of coronagraphs and optimization of each design

- sensitivity of spectral differential imaging w.r.t. filters width and separation - detector related parameters (Flat Field)- and many others …

2. once specs are defined => derive performance function of astrophysical parameters (Sp, dist., age, planet mass, planet model, …)

3. provide input to the Exposure Time Calculator

A very useful TOOL to study the whole system and sub-systemsCan be adapted to other projects

6A. Boccaletti

Pasadena, Sept. 28-29th

Some results

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offset pointing in mas

Normalized contrast

peak attenuation

contrast at 0.1"

contrast at 0.5"

contrast at 1"

contrast at 2"

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chromatic aberrations in nm

Normalized contrast

peak attenuation

contrast at 0.1"

contrast at 0.5"

contrast at 1"

contrast at 2"

[Boccaletti et al.]

7A. Boccaletti

Pasadena, Sept. 28-29th

Some implications for TPF-C1. WF active control vs. Calibration

- WF control needs long integrations to sense at the 10-9 - 10-10 level (as long as detection)

- snr, convergence for iterative techniques- several images for global techniques [Bordé et al.]

- stability issues (system and active element)

- Calibration (differential imaging) is starting from a higher level (10-5 - 10-6) - speckle noise is reduced after the calibration- long integrations to reduce photon noise- dedicated image processing- stability is required but no active elements (critical for space mission)

2. Coronagraphy- so many corono. that a comprehensive comparison becomes difficult- studies have to be more system oriented

optical quality, coatings & ghosts, phase, positioning accuracy, stability, chromaticity, out of band flux, polarization, …detector artifacts (FF, remanence, smearing, …)

- can we make it, at which level of accuracy ???

Some trade offs and evaluation of systematics are needed …

8A. Boccaletti

Pasadena, Sept. 28-29th

a few more words on calibration …

Calibration may allow lower constraints on the - coronagraph performance (a 10-6/10-7 raw contrast instead of 10-9/10-10)- coronagraph manufacturing defects- IWA and stellar leakage- optical quality (PSD and amplitude of phase defects)- chromaticity- …

- Report these constraints on the calibration unit (might be easier)- The underlying point is that Signal to Noise is THE parameter to considered in TPF-C- CALIBRATION has to be CONSIDERED in TPF-C thoroughly

What is the best calibration concept for TPF-C ? : spectral: polarisation: coherence

Probably, WF control and Calibration will have to be combined at some point

9A. Boccaletti

Pasadena, Sept. 28-29th

Toward collaboration …We are talking about US/EU collaboration for years. Workshops were organized :

- Leiden Workshop, 2004- Villefranche IAU, 2005- this workshop, 2006- other to come hopefully …

Collaboration not very concrete so far !!!Why ? Space agencies do not always share the same views …. (but don’t say it)But, SCIENCE must remain the driver of any projects !!!we all agree that the complementarity Vis/IR, corono/interfero is crucial for the study of telluric planets. At some point NASA/ESA will have to collaborate for a coronagraphic mission (like for HST, JWST, TPF-I, …)

Can we push agencies to collaborate …. Probably, if we do so …

How ?- combine efforts : initiate international strategy for development of coronagraphs and wavefront sensing in order to address some critical points in a coherent way- share expertise - share facilities (optical benches) within some sort of network - investigate manufacturers in an international way- collaborate on publications

collaborate through

Students, Postdocs