J/A+A/686/A33 FITS images of HR8799 observed with MIRI (Boccaletti+, 2024)
Imaging detection of the inner dust belt and the four exoplanets in the
HR 8799 system with JWST's MIRI coronagraph.
Boccaletti A., Malin M., Baudoz P., Tremblin P., Perrot C., Rouan D.,
Lagage P.-O., Whiteford N., Molliere P., Waters R., Henning T., Decin L.,
Guedel M., Vandenbussche B., Absil O., Argyriou I., Bouwman J., Cossou C.,
Coulais A., Gastaud R., Glasse A., Glauser A.M., Kamp I., Kendrew S.,
Krause O., Lahuis F., Mueller M., Olofsson G., Patapis P., Pye J., Royer P.,
Serabyn E., Scheithauer S., Colina L., van Dishoeck E.F., Ostlin G.,
Ray T.P., Wright G.
<Astron. Astrophys. 686, A33 (2024)>
=2024A&A...686A..33B 2024A&A...686A..33B (SIMBAD/NED BibCode)
ADC_Keywords: Stars, double and multiple ; Exoplanets ; Infrared
Keywords: techniques: high angular resolution - techniques: image processing -
planets and satellites: detection - stars: individual: HR 8799
Abstract:
The MIRI instrument on board JWST is now offering high-contrast
imaging capacity at mid-IR wavelengths, thereby opening a completely
new field of investigation for characterizing young exoplanetary
systems.
The multiplanet system HR 8799 is the first target observed with
MIRI's coronagraph as part of the MIRI-EC Guaranteed Time Observations
(GTO) exoplanet program, launched in November 2022. We obtained deep
observations in three coronagraphic filters, from ∼10 to 15um (F1065C,
F1140C, F1550C), and one standard imaging filter at ∼20um (F2100W).
The goal of this work is to extract photometry for the four planets
and to detect and investigate the distribution of circumstellar dust.
Using dedicated observations of a reference star, we tested several
algorithms to subtract the stellar diffraction pattern, while
preserving the fluxes of planets, which can be significantly affected
by over-subtraction. To obtain correct measurements of the planet's
flux values, the attenuation by the coronagraphs as a function of
their position must be accounted for, as well as an estimation of the
normalisation with respect to the central star. We tested several
procedures to derive averaged photometric values and error bars.
These observations have enabled us to obtain two main results. First,
the four planets in the system are well recovered and we were able to
compare their mid-IR fluxes, combined with near-IR flux values from
the literature, to two exoplanet atmosphere models: ATMO and Exo-REM.
As a main outcome, the MIRI photometric data points imply larger radii
(1.04 or 1.17RJ for planet b) and cooler temperatures (950 or 1000K
for planet b), especially for planet b, in better agreement with
evolutionary models. Second, these JWST/MIRI coronagraphic data also
deliver the first spatially resolved detection of the inner warm
debris disk, the radius of which is constrained to about 15au, with
flux densities that are comparable to (but lower than) former
unresolved spectroscopic measurements with Spitzer.
The coronagraphs coming from MIRI ushers in a new vision of known
exoplanetary systems that differs significantly from shorter
wavelength, high-contrast images delivered by extreme adaptive optics
from the ground. Inner dust belts and background galaxies become
dominant at some mid-IR wavelengths, potentially causing confusion in
detecting exoplanets. Future observing strategies and data reductions
ought to take such features into account.
Description:
Images obtained with MIRI coronagraph in filter F1065C (10.575um),
F1140C (11.30um) and F1550C (15.50um) of the HR8799 system. The image
contains 200x200 pixels, the angular size of which is 110mas.
Intensities are calibrated in MJy/sr. Intensities of planets and the
inner disk cannot be directly measured from pixel values even if
photometrically calibrated since planet's fluxes depend on the
coronagraphs' transmission which is 2D function of the planets'
position.
Objects:
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RA (2000) DE Designation(s)
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23 07 28.72 +21 08 03.3 HR 8799 = HD 218396
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 127 3 List of fits images
fits/* . 3 Individual fits images
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 22 I3 --- Nx Number of pixels along X-axis
24- 26 I3 --- Ny Number of pixels along Y-axis
28- 37 A10 "datime" Obs.date Observation date
39- 41 I3 Kibyte size Size of FITS file
43- 84 A42 --- FileName Name of FITS file, in subdirectory fits
86-127 A42 --- Title Title of the FITS file
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Acknowledgements:
Anthony Boccaletti, anthony.boccaletti(at)obspm.fr
(End) Patricia Vannier [CDS] 15-Mar-2024