A double‐modulation technique for obtaining high‐resolution energy‐differentiated electron transmission spectra

1974 ◽  
Vol 45 (3) ◽  
pp. 391-394 ◽  
Author(s):  
F. D. Schowengerdt ◽  
D. E. Golden
Keyword(s):  
High Resolution ◽  
Transmission Spectra ◽  
Electron Transmission ◽  
Modulation Technique ◽  
Double Modulation

scholarly journals The Effects of Stellar Activity on Optical High-resolution Exoplanet Transmission Spectra

2018 ◽  
Vol 156 (5) ◽  
pp. 189 ◽  
Author(s):  
P. Wilson Cauley ◽  
Christoph Kuckein ◽  
Seth Redfield ◽  
Evgenya L. Shkolnik ◽  
Carsten Denker ◽  
...  
Keyword(s):  
High Resolution ◽  
Transmission Spectra ◽  
Stellar Activity

scholarly journals petitRADTRANS

2019 ◽  
Vol 627 ◽  
pp. A67 ◽  
Author(s):  
P. Mollière ◽  
J. P. Wardenier ◽  
R. van Boekel ◽  
Th. Henning ◽  
K. Molaverdikhani ◽  
...  
Keyword(s):  
High Resolution ◽  
Optical Constants ◽  
Emission Spectra ◽  
Transmission Spectra ◽  
Low Resolution ◽  
Cloud Particle ◽  
Hot Jupiters ◽  
Higher Temperature ◽  
Python Package

We present the easy-to-use, publicly available, Python package petitRADTRANS, built for the spectral characterization of exoplanet atmospheres. The code is fast, accurate, and versatile; it can calculate both transmission and emission spectra within a few seconds at low resolution (λ/Δλ = 1000; correlated-k method) and high resolution (λ/Δλ = 106; line-by-line method), using only a few lines of input instruction. The somewhat slower, correlated-k method is used at low resolution because it is more accurate than methods such as opacity sampling. Clouds can be included and treated using wavelength-dependent power law opacities, or by using optical constants of real condensates, specifying either the cloud particle size, or the atmospheric mixing and particle settling strength. Opacities of amorphous or crystalline, spherical or irregularly-shaped cloud particles are available. The line opacity database spans temperatures between 80 and 3000 K, allowing to model fluxes of objects such as terrestrial planets, super-Earths, Neptunes, or hot Jupiters, if their atmospheres are hydrogen-dominated. Higher temperature points and species will be added in the future, allowing to also model the class of ultra hot-Jupiters, with equilibrium temperatures Teq ≳ 2000 K. Radiative transfer results were tested by cross-verifying the low- and high-resolution implementation of petitRADTRANS, and benchmarked with the petitCODE, which itself is also benchmarked to the ATMO and Exo-REM codes. We successfully carried out test retrievals of synthetic JWST emission and transmission spectra (for the hot Jupiter TrES-4b, which has a Teq of ∼1800 K).

Thickness-dependent interference structure in the 0—15-eV electron transmission spectra of rare-gas films

1984 ◽  
Vol 30 (8) ◽  
pp. 4292-4296 ◽  
Author(s):  
G. Perluzzo ◽  
L. Sanche ◽  
C. Gaubert ◽  
R. Baudoing
Keyword(s):  
Rare Gas ◽  
Transmission Spectra ◽  
Interference Structure ◽  
Electron Transmission

scholarly journals Combining low- to high-resolution transit spectroscopy of HD 189733b

2018 ◽  
Vol 612 ◽  
pp. A53 ◽  
Author(s):  
Lorenzo Pino ◽  
David Ehrenreich ◽  
Aurélien Wyttenbach ◽  
Vincent Bourrier ◽  
Valerio Nascimbeni ◽  
...  
Keyword(s):  
High Resolution ◽  
Wavelength Range ◽  
Near Infrared ◽  
Theoretical Models ◽  
Apparent Size ◽  
Transmission Spectra ◽  
Infrared Transmission ◽  
Line Spread Function ◽  
Building Models ◽  
Exoplanetary Atmospheres

Space-borne low- to medium-resolution (ℛ ~ 102–103) and ground-based high-resolution spectrographs (ℛ ~ 105) are commonly used to obtain optical and near infrared transmission spectra of exoplanetary atmospheres. In this wavelength range, space-borne observations detect the broadest spectral features (alkali doublets, molecular bands, scattering, etc.), while high-resolution, ground-based observations probe the sharpest features (cores of the alkali lines, molecular lines). The two techniques differ by several aspects. (1) The line spread function of ground-based observations is ~103 times narrower than for space-borne observations; (2) Space-borne transmission spectra probe up to the base of thermosphere (P ≳ 10−6 bar), while ground-based observations can reach lower pressures (down to ~10−11 bar) thanks to their high resolution; (3) Space-borne observations directly yield the transit depth of the planet, while ground-based observations can only measure differences in the apparent size of the planet at different wavelengths. These differences make it challenging to combine both techniques. Here, we develop a robust method to compare theoretical models with observations at different resolutions. We introduce πη, a line-by-line 1D radiative transfer code to compute theoretical transmission spectra over a broad wavelength range at very high resolution (ℛ ~ 106, or Δλ ~ 0.01 Å). An hybrid forward modeling/retrieval optimization scheme is devised to deal with the large computational resources required by modeling a broad wavelength range ~0.3–2 μm at high resolution. We apply our technique to HD 189733b. In this planet, HST observations reveal a flattened spectrum due to scattering by aerosols, while high-resolution ground-based HARPS observations reveal sharp features corresponding to the cores of sodium lines. We reconcile these apparent contrasting results by building models that reproduce simultaneously both data sets, from the troposphere to the thermosphere. We confirm: (1) the presence of scattering by tropospheric aerosols; (2) that the sodium core feature is of thermospheric origin. When we take into account the presence of aerosols, the large contrast of the core of the sodium lines measured by HARPS indicates a temperature of up to ~10 000K in the thermosphere, higher than what reported in the literature. We also show that the precise value of the thermospheric temperature is degenerate with the relative optical depth of sodium, controlled by its abundance, and of the aerosol deck.

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