J/A+A/683/A242 NaI 5896, KI 769 SST normalized line profiles (Canocchi+, 2024)
3D non-LTE modeling of the stellar center-to-limb variation for transmission
spectroscopy studies. Na I D and K I resonance lines in the Sun.
Canocchi G., Lind K., Lagae C., Pietrow A.G.M., Amarsi A.M., Kiselman D.,
Andriienko O., Hoeijmakers H.J.
<Astron. Astrophys. 683, A242 (2024)>
=2024A&A...683A.242C 2024A&A...683A.242C (SIMBAD/NED BibCode)
ADC_Keywords: Sun ; Spectroscopy
Keywords: Sun: atmosphere - line: formation - line: profiles -
planets and satellites: atmospheres - techniques: spectroscopic
Abstract:
Transmission spectroscopy is one of the most powerful techniques used
to characterize transiting exoplanets, since it allows for the
abundance of the atomic and molecular species in the planetary
atmosphere to be measured. However, stellar lines may bias the
determination of such abundances if their center-to-limb variations
(CLVs) are not properly accounted for.
This paper aims to show that three-dimensional (3D) radiation
hydrodynamic models and the assumption of non-local thermodynamic
equilibrium (non-LTE) line formation are required for an accurate
modeling of the stellar CLV of the NaI D1 and KI resonance lines on
transmission spectra.
We modeled the CLV of the NaI D1 and KI resonance lines in the Sun
with 3D non-LTE radiative transfer. The synthetic spectra were
compared to solar observations with high spatial and spectral
resolution, including new data collected with the CRISP instrument at
the Swedish 1-m Solar Telescope between mu=0.1 and mu=1.0.
Our 3D non-LTE modeling of the NaI D1 resonance line at 5896Å and
the KI 7699Å resonance line in the Sun is in good agreement with
the observed CLV in the solar spectrum. Moreover, the simulated CLV
curve for a Jupiter-Sun system inferred with a 3D non-LTE analysis
shows significant differences from the one obtained from a 1D
atmosphere. The latter does indeed tend to overestimate the amplitude
of the transmission curve by a factor that is on the same order of
magnitude as a planetary absorption depth (i.e., up to 0.2%).
This work highlights the fact that to correctly characterize
exoplanetary atmospheres, 3D non-LTE synthetic spectra ought to be
used to estimate the stellar CLV effect in transmission spectra of
solar-like planet hosts. Moreover, since different spectral lines show
different CLV curves for the same geometry of the planet-star system,
it is fundamental to model the CLV individually for each line of
interest. The work will be extended to other lines and FGK-type stars,
allowing for synthetic high-resolution spectra to mitigate the stellar
contamination of low-resolution planetary spectra, for example, those
drawn from JWST.
Description:
There are two files representing the normalized intensity profiles of
the NaI 5896Å and KI 7699Å resonance lines in the Sun, observed
with the CRISP instrument on the Swedish 1-m Solar Telescope (SST) in
La Palma, and reduced as described in Sect. 2.1 of the paper.
In each file, the columns represent: the wavelength (in Angstrom), the
normalized intensity at different mu-angles, from the limb at mu=0.1
("Imu01") to the disk center at mu=1.0 ("Imu10"). In particular, we
present the normalized intensity spectra for the following 12
mu-angles: 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.55, 0.6, 0.8,
and 1.0.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
k7699sp.dat 253 27 Normalized intensity spectra at 12 mu-angles
for the KI resonance line
na5896sp.dat 253 39 Normalized intensity spectra at 12 mu-angles
for the Na D1 line
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Byte-by-byte Description of file: k7699sp.dat na5896sp.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- N1 [0/38] Sequential number
4- 5 I2 --- N2 [0/38] Sequential number
7- 24 F18.13 0.1nm lambda Wavelength datapoints in Å
26- 43 F18.16 --- Imu01 Normalized intensity at mu=0.1
45- 62 F18.16 --- Imu015 Normalized intensity at mu=0.15
64- 81 F18.16 --- Imu02 Normalized intensity at mu=0.2
83-100 F18.16 --- Imu025 Normalized intensity at mu=0.25
102-119 F18.16 --- Imu03 Normalized intensity at mu=0.3
121-138 F18.16 --- Imu035 Normalized intensity at mu=0.35
140-157 F18.16 --- Imu04 Normalized intensity at mu=0.4
159-177 F19.17 --- Imu045 Normalized intensity at mu=0.45
179-196 F18.16 --- Imu055 Normalized intensity at mu=0.55
198-215 F18.16 --- Imu06 Normalized intensity at mu=0.6
217-234 F18.16 --- Imu08 Normalized intensity at mu=0.8
236-253 F18.16 --- Imu10 Normalized intensity at mu=1.0
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Acknowledgements:
Gloria Canocchi, gloria.canocchi(at)astro.su.se
(End) Patricia Vannier [CDS] 28-Dec-2023