J/AJ/156/276 Exoplanetary atmospheric properties with MIRI (Danielski+, 2018)
Atmospheric characterization of directly imaged exoplanets with JWST/MIRI.
Danielski C., Baudino J.-L., Lagage P.-O., Boccaletti A., Gastaud R.,
Coulais A., Bezard B.
<Astron. J., 156, 276-276 (2018)>
=2018AJ....156..276D 2018AJ....156..276D (SIMBAD/NED BibCode)
ADC_Keywords: Models ; Exoplanets
Keywords: instrumentation: high angular resolution -
instrumentation: spectrographs - planets and satellites: atmospheres -
planets and satellites: fundamental parameters -
planets and satellites: gaseous planets - telescopes
Abstract:
The Mid-Infrared instrument (MIRI) on board the James Webb Space Telescope
will perform the first ever characterization of young giant exoplanets
observed by direct imaging in the 5-28 µm spectral range. This
wavelength range is key for both determining the bolometric luminosity
of the cool known exoplanets and for accessing the strongest ammonia bands.
In conjunction with shorter wavelength observations, MIRI will enable
a more accurate characterization of the exoplanetary atmospheric
properties. Here we consider a subsample of the currently known exoplanets
detected by direct imaging, and we discuss their detectability with MIRI,
either using the coronagraphic or the spectroscopic modes. By using the
Exo-REM atmosphere model, we calculate the mid-infrared emission spectra
of 14 exoplanets, and we simulate MIRI coronagraphic or spectroscopic
observations. Specifically, we analyze four coronagraphic observational
setups, which depend on (i) the target-star and reference-star offset (0,
3, 14 mas), (ii) the wavefront-error (130, 204 nm root mean square), and
(iii) the telescope jitter amplitude (1.6, 7 mas). We then determine the
signal-to-noise and integration time values for the coronagraphic targets
whose planet-to-star contrasts range from 3.9 to 10.1 mag. We conclude
that all the MIRI targets should be observable with different degrees of
difficulty, which depends on the final in-flight instrument performances.
Furthermore, we test for detection of ammonia in the atmosphere of the
coolest targets. Finally, we present the case of HR 8799 b to discuss what
MIRI observations can bring to the knowledge of a planetary atmosphere,
either alone or in combination with shorter wavelength observations.
Description:
Among JWST instruments, the Mid-Infrared Instrument (MIRI; Rieke et al.
2015PASP..127..584R 2015PASP..127..584R; Wright et al. 2015PASP..127..595W 2015PASP..127..595W and references
therein) will be pivotal to the characterization of gas-giant exoplanets.
In this paper, we present the exoplanetary science that can be performed
with the 4QPM coronagraph and low-resolution spectrometer observational
modes. MIRI coronagraphic imaging incorporates one Lyot mask (30"x30")
at λ=23 µm and three four-quadrant phase masks (4QPM) at
λ= 10.65, 11.40, 15.50 µm, which cover a field of view of 24"x24"
(Rouan et al. 2000PASP..112.1479R 2000PASP..112.1479R).
To build the diffraction patterns, we followed the principle of operation
of the 4QPM coronagraph (Figure 1 by Boccaletti et al. 2015PASP..127..633B 2015PASP..127..633B).
Note that, in order to encompass different observational settings, we
considered five specific cases k to account for variations of the wavefront
error (WFE), for different amplitudes of the telescope jitter and for
different offsets between the target star and the reference star. Table 4
shows the configuration for these cases: an optimistic one (kA), a
pessimistic one (kD), and two intermediate cases (kB and kC). Each
case represents a different configuration of the following values: for
the wavefront error we used WFE∼130 nm and WFE∼204 nm root mean square
(rms; also used in Boccaletti et al. 2015PASP..127..633B 2015PASP..127..633B), while for the
amplitude of the jitter (jamp) of the pointing, we used a minimum value
of 1.6 mas (E. Nalan 2018, private communication, 2015 July 8)
and a maximum value of 7 mas (1σ dispersion value).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table10.dat 37 100 F1065C 1σ contrast curves as a function
of the angular distance for observational cases
kA, kB, kC, kD
table11.dat 37 100 F1140C 1σ contrast curves as a function
of the angular distance for observational cases
kA, kB, kC, kD
table12.dat 37 100 F1550C 1σ contrast curves as a function
of the angular distance for observational cases
kA, kB, kC, kD
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See also:
J/ApJ/813/47 : Model atmospheres of irradiated exoplanets (Molliere+, 2015)
Byte-by-byte Description of file: table10.dat table11.dat table12.dat
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Bytes Format Units Label Explanations
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1- 5 F5.2 arcsec Dist [0.11/11] Angular distance
7- 13 E7.2 --- kA [5e-09/9.9e-06] Contrast curve value for the kA
case (1)
15- 21 E7.2 --- kB [5.9e-08/0.00012] Contrast curve value for the kB
case (1)
23- 29 E7.2 --- kC [1.1e-07/0.00017] Contrast curve value for the kC
case (1)
31- 37 E7.2 --- kD [3.4e-07/0.00051] Contrast curve value for the kD
case (1)
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Note (1): The different cases analyzed and their respective instrumental
configuration for the observations (Table 4 of this paper):
------------------------------------------------------------------------------
Case|WFE rms|Jitter amplitude|Star (x,y) |Reference (x,y)|Star-Reference offset
| (nm) | (mas) | (mas) | (mas) | (mas)
------------------------------------------------------------------------------
kA | 130 | 1.6 | 0. , 0. | 0. , 0. | 0
kB | 130 | 1.6 | 0. , 0. | +2.12,+2.12 | 3
kC | 204 | 7. | 0. , 0. | +2.12,+2.12 | 3
kD | 204 | 7. |-4.95,-4.95| +4.95,+4.95 | 14
------------------------------------------------------------------------------
WFE is the wavefront error. The value of (x,y) position of star and reference
are relative to the center of the coronagraphic mask.
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History:
From electronic version of the journal
(End) Tiphaine Pouvreau [CDS] 23-Apr-2019