Modeling the Transmission Spectra of WASP-31b

2018 ◽  
Vol 14 (S345) ◽  
pp. 383-385
Author(s):  
J. Chouqar ◽  
M. L. Morales ◽  
A. Daassou ◽  
A. Jabiri ◽  
Z. Benkhaldoun
Keyword(s):  
Orbital Period ◽  
Transmission Spectrum ◽  
Scale Height ◽  
Transmission Spectra ◽  
Dwarf Star ◽  
Near Ir ◽  
Transmission Spectroscopy ◽  
Good Target ◽  
Ir Transmission ◽  
Type V

AbstractWasp-31b is a planet of 0.48 Jupiter masses and 1.55 Jupiter radii, with orbital period of 3.4-days around a metal-poor, late-F-type, V = 11.7 dwarf star. The planet has a large atmospheric scale height that makes it a good target for transmission spectroscopy. Sing et al (2014) presented an optical and near-IR transmission spectrum of the atmosphere of WASP-31b obtained with the HST and show the presence of a strong potassium line. In contrast, Gibson et al. (2017) reports a spectrum of the atmosphere of WASP-31b, obtained with the FORS2 instrument on the VLT and find that there is no strong potassium line. Here, we take those two datasets and, using models, we try to find a case where both solutions are correct by considering different cloud scenarios.

scholarly journals Near-IR Transmission Spectrum of HAT-P-32b usingHST/WFC3

2017 ◽  
Vol 154 (1) ◽  
pp. 39 ◽  
Author(s):  
M. Damiano ◽  
G. Morello ◽  
A. Tsiaras ◽  
T. Zingales ◽  
G. Tinetti
Keyword(s):  
Transmission Spectrum ◽  
Near Ir ◽  
Ir Transmission

scholarly journals An HST optical-to-near-IR transmission spectrum of the hot Jupiter WASP-19b: detection of atmospheric water and likely absence of TiO

2013 ◽  
Vol 434 (4) ◽  
pp. 3252-3274 ◽  
Author(s):  
C. M. Huitson ◽  
D. K. Sing ◽  
F. Pont ◽  
J. J. Fortney ◽  
A. S. Burrows ◽  
...  
Keyword(s):  
Transmission Spectrum ◽  
Atmospheric Water ◽  
Near Ir ◽  
Ir Transmission ◽  
Hot Jupiter

scholarly journals Role of the impact parameter in exoplanet transmission spectroscopy

2020 ◽  
Vol 640 ◽  
pp. A134
Author(s):  
X. Alexoudi ◽  
M. Mallonn ◽  
E. Keles ◽  
K. Poppenhäger ◽  
C. von Essen ◽  
...  
Keyword(s):  
Impact Parameter ◽  
Transmission Spectrum ◽  
Near Infrared ◽  
Transmission Spectra ◽  
Orbital Parameters ◽  
Transmission Spectroscopy ◽  
Limb Darkening ◽  
The Impact ◽  
Error Envelope

Context. Transmission spectroscopy is a promising tool for the atmospheric characterization of transiting exoplanets. Because the planetary signal is faint, discrepancies have been reported regarding individual targets. Aims. We investigate the dependence of the estimated transmission spectrum on deviations of the orbital parameters of the star-planet system that are due to the limb-darkening effects of the host star. We describe how the uncertainty on the orbital parameters translates into an uncertainty on the planetary spectral slope. Methods. We created synthetic transit light curves in seven different wavelength bands, from the near-ultraviolet to the near-infrared, and fit them with transit models parameterized by fixed deviating values of the impact parameter b. First, we performed a qualitative study to illustrate the effect by presenting the changes in the transmission spectrum slope with different deviations of b. Then, we quantified these variations by creating an error envelope (for centrally transiting, off-center, and grazing systems) based on a derived typical uncertainty on b from the literature. Finally, we compared the variations in the transmission spectra for different spectral types of host stars. Results. Our simulations show a wavelength-dependent offset that is more pronounced at the blue wavelengths where the limb-darkening effect is stronger. This offset introduces a slope in the planetary transmission spectrum that becomes steeper with increasing b values. Variations of b by positive or negative values within its uncertainty interval introduce positive or negative slopes, thus the formation of an error envelope. The amplitude from blue optical to near-infrared wavelength for a typical uncertainty on b corresponds to one atmospheric pressure scale height and more. This impact parameter degeneracy is confirmed for different host types; K stars present prominently steeper slopes, while M stars indicate features at the blue wavelengths. Conclusions. We demonstrate that transmission spectra can be hard to interpret, basically because of the limitations in defining a precise impact parameter value for a transiting exoplanet. This consequently limits a characterization of its atmosphere.

Revisiting the atmosphere of HD 209458b with HARPS-N, CARMENES and ESPRESSO

2020 ◽  
Author(s):  
Núria Casasayas-Barris ◽  
Enric Palle ◽  
Monika Stangret ◽  
Guo Chen ◽  
Fei Yan ◽  
...  
Keyword(s):  
High Resolution ◽  
Time Evolution ◽  
Transmission Spectrum ◽  
State Of The Art ◽  
Signal To Noise Ratio ◽  
Light Curves ◽  
High Resolution Spectroscopy ◽  
Transmission Spectra ◽  
Signal To Noise ◽  
Transmission Spectroscopy

<p>HD 209458b was the first transiting planet discovered, and the first for which its atmosphere, in particular Na I, was detected. With time, it has become one of the most studied planets, with a large diversity of atmospheric studies using low- and high-resolution spectroscopy. Here, we present the analysis of high-resolution transmission spectroscopy of HD 209458b using a total of five transit observations with HARPS-N and CARMENES spectrographs. In contrast to previous studies where atmospheric Na I absorption is detected, we find that, for all of the nights, either individually or combined, the transmission spectra can be explained by the combination of the centre-to-limb variation and the Rossiter-McLaughlin effect. Thus, the transmission spectrum reveals no detectable Na I absorption in HD 209458b. This is also observed in the time-evolution maps and transmission light curves, but at lower signal-to-noise ratio. Other strong lines such as Hα, Ca II IRT, the Mg I triplet region, and K I D1 are analysed, and are also consistent with the modelled effects, without considering any contribution from the exoplanet atmosphere. New ESPRESSO observations, with state-of-the-art stability and considerably larger signal-to-noise, confirm the results of our study and will also be shown.</p>

The first atmospheric characterisation of Wasp-15b with Gaussian Process modelling

2021 ◽  
Author(s):  
Dominique Petit dit de la Roche ◽  
Mario van den Ancker ◽  
Paulo Miles Páez
Keyword(s):  
Gaussian Process ◽  
Transmission Spectrum ◽  
Scale Height ◽  
Process Modelling ◽  
Low Density ◽  
Transmission Spectroscopy ◽  
Excellent Candidate ◽  
Systematic Noise ◽  
Hot Jupiter

<p>Wasp-15 b is an inflated hot Jupiter orbiting a bright host star. Its low density and consequent large atmospheric scale height make it an excellent candidate for atmospheric characterization using transmission spectroscopy. In fact, it has previously been observed with the FORS2 spectrograph on the VLT, but large systematics have so far prevented this data from being used. Here, we show that Gaussian Process modelling can remove systematic noise features with amplitudes up to that of the transit signal, allowing us to achieve a precision comparable to later data without the systematics. We present the first transmission spectrum of the atmosphere of Wasp-15 b and compare it to theoretical spectra to discuss the implications.</p>

IR Spectroscopy of Polyperfluoroethylene Oxide Lubricants on Amorphous Carbon

1989 ◽  
Vol 43 (3) ◽  
pp. 481-483 ◽  
Author(s):  
David D. Saperstein
Keyword(s):  
Thin Film ◽  
Ir Spectroscopy ◽  
Amorphous Carbon ◽  
Transmission Spectrum ◽  
Reflection Spectrum ◽  
Grazing Incidence ◽  
Transmission Spectra ◽  
Ir Transmission ◽  
Ft Ir ◽  
Reflecting Surface

The FT-IR transmission spectrum of 30 Å of a polyperfluoroethylene oxide lubricant on amorphous carbon is shown to be proportional to the transmission spectrum of a 0.4-μm film, and thus, there appears to be little or no interaction of the lubricant with amorphous carbon. These transmission spectra are dramatically different from the spectrum of the lubricant on a carbon-overcoated thin-film disk recorded at grazing incidence. The alteration of the grazing incidence reflection spectrum is due to polarization changes of the light when a strong absorber is measured near a reflecting surface.

scholarly journals The GTC exoplanet transit spectroscopy survey

2018 ◽  
Vol 609 ◽  
pp. A33 ◽  
Author(s):  
H. Parviainen ◽  
E. Pallé ◽  
G. Chen ◽  
L. Nortmann ◽  
F. Murgas ◽  
...  
Keyword(s):  
High Altitude ◽  
Transmission Spectrum ◽  
Rayleigh Scattering ◽  
Equilibrium Temperature ◽  
Transmission Spectra ◽  
Spectroscopy Analysis ◽  
Orbital Parameters ◽  
Transmission Spectroscopy ◽  
The Common ◽  
20 Nm

Aims. We set out to study the atmosphere of WASP-80b, a warm inflated gas giant with an equilibrium temperature of ~800 K, using ground-based transmission spectroscopy covering the spectral range from 520 to 910 nm. The observations allow us to probe the existence and abundance of K and Na in WASP-80b’s atmosphere, existence of high-altitude clouds, and Rayleigh-scattering in the blue end of the spectrum. Methods. We observed two spectroscopic time series of WASP-80b transits with the OSIRIS spectrograph installed in the Gran Telescopio Canarias (GTC), and use the observations to estimate the planet’s transmission spectrum between 520 nm and 910 nm in 20 nm-wide passbands, and around the K I and Na I resonance doublets in 6 nm-wide passbands. We jointly model three previously published broadband datasets consisting of 27 light curves, prior to a transmission spectroscopy analysis in order to obtain improved estimates of the planet’s orbital parameters, average radius ratio, and stellar density. The parameter posteriors from the broadband analysis are used to set informative priors on the transmission spectroscopy analysis. The final transmission spectroscopy analyses are carried out jointly for the two nights using a divide-by-white approach to remove the common-mode systematics, and Gaussian processes to model the residual wavelength-dependent systematics. Results. We recover a flat transmission spectrum with no evidence of Rayleigh scattering or K I or Na I absorption, and obtain an improved system characterisation as a by-product of the broadband- and GTC-dataset modelling. The transmission spectra estimated separately from the two observing runs are consistent with each other, as are the transmission spectra estimated using either a parametric or nonparametric systematics model. The flat transmission spectrum favours an atmosphere model with high-altitude clouds over cloud-free models with stellar or sub-stellar metallicities. Conclusions. Our results disagree with the recently published discovery of strong K I absorption in WASP-80b’s atmosphere based on ground-based transmission spectroscopy with FORS2 at VLT.

scholarly journals The influence of the surface density of oriented nickel networks on the conducting electrode’s optical transparency

2021 ◽  
Vol 2086 (1) ◽  
pp. 012028
Author(s):  
I R Nizameev ◽  
G R Nizameeva ◽  
M K Kadirov
Keyword(s):  
Electrical Conductivity ◽  
Transmission Spectrum ◽  
Glass Substrate ◽  
Surface Density ◽  
Optical Transparency ◽  
Transmission Spectra ◽  
Near Ir ◽  
Deposited Metal ◽  
Optimal Values ◽  
Uv Visible

Abstract This study is part of the work on the creation of a transparent conductive coating based on oriented nanonetwork and submicron nickel fibres. It is devoted to finding the optimal values of electrical conductivity and optical transparency of the developed coating. In this work, we study the transmission spectra of oriented nickel networks on a glass substrate in the UV, visible and near-IR regions at different amounts of deposited metal. An exciting feature of the coating was discovered: in the range of 950 nm and above, there is a "bend" of the transmission spectrum downward. This bend (increased absorption of radiation in the near-IR region) is observed only in the presence of nickel nanonetwork and is not typical for a pure submicron network.

scholarly journals An empirical infrared transit spectrum of Earth: opacity windows and biosignatures

2019 ◽  
Vol 489 (1) ◽  
pp. 196-204 ◽  
Author(s):  
Evelyn J R Macdonald ◽  
Nicolas B Cowan
Keyword(s):  
Atmospheric Chemistry ◽  
Lower Atmosphere ◽  
High Dispersion ◽  
Fourier Transform Spectrometer ◽  
Transmission Spectra ◽  
Near Ir ◽  
James Webb Space Telescope ◽  
Ir Transmission ◽  
Chemistry Experiment

Abstract The Atmospheric Chemistry Experiment Fourier Transform Spectrometer on the SCISAT satellite has been measuring infrared (IR) transmission spectra of Earth during Solar occultations since 2004. We use these data to build an IR transit spectrum of Earth. Regions of low atmospheric opacity, known as windows, are of particular interest, as they permit observations of the planet’s lower atmosphere. Even in the absence of clouds or refraction, imperfect transmittance leads to a minimum effective thickness of hmin ≈ 4 km in the 10–12 $\mu \mathrm{m}$ opacity window at a spectral resolution of R = 103. None the less, at R = 105, the maximum transmittance at the surface is around ${70}{{{\ \rm per\ cent}}}$. In principle, one can probe the troposphere of an Earth-like planet via high-dispersion transit spectroscopy in the mid-IR; in practice aerosols and/or refraction likely make this impossible. We simulate the transit spectrum of an Earth-like planet in the TRAPPIST-1 system. We find that a long-term near-IR (NIR) campaign with the James Webb Space Telescope(JWST) could readily detect CO2, establishing the presence of an atmosphere. A mid-IR campaign or longer NIR campaign would be more challenging, but in principle could detect H2O and the biosignatures O3 and CH4.

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