FP-APW+lo calculations of the electronic and optical properties of alkali metal sulfides under pressure

Khachai, H.; Khenata, R.; Bouhemadou, A.; Haddou, A.; Reshak, A.H.; Amrani, B.; Rached, D.; Soudini, B.

doi:10.1088/0953-8984/21/9/095404

Cited by 41 publications

(24 citation statements)

References 38 publications

(44 reference statements)

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“…The optical properties (i.e. complex indices of refraction as a function of wavelength) were compiled in order of decreasing condensation temperature from 1316 to 90 K for MgSiO3, Fe-poor Mg2SiO4, Na2S, MnS, KCl, and Titan tholin with all condensates at pressures 10 −3 bar (Egan & Hilgeman 1975;Zeidler et al 2011;Khachai et al 2009;Huffman & Wild 1967;Palik 1998;Khare et al 1984;Ramirez et al 2002). As in Sing et al (2013) cross-sections as a function of wavelength were computed with Mie theory which were then used to compute the transmission spectra using the expression for the planetary altitude derived in Lecavelier Des Etangs et al (2008a).…”

Section: Mie Scattering Dustmentioning

confidence: 99%

HST hot-Jupiter transmission spectral survey: haze in the atmosphere of WASP-6b

Nikolov

Sing

Burrows

et al. 2014

Monthly Notices of the Royal Astronomical Society

152

142

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We report Hubble Space Telescope (HST) optical to near-infrared transmission spectroscopy of the hot Jupiter WASP-6b, measured with the Space Telescope Imaging Spectrograph (STIS) and Spitzer's InfraRed Array Camera (IRAC). The resulting spectrum covers the range 0.29 − 4.5 µm. We find evidence for modest stellar activity of WASP-6 and take it into account in the transmission spectrum. The overall main characteristic of the spectrum is an increasing radius as a function of decreasing wavelength corresponding to a change of ∆(R p /R * ) = 0.0071 from 0.33 to 4.5 µm. The spectrum suggests an effective extinction cross-section with a power law of index consistent with Rayleigh scattering, with temperatures of 973 ± 144 K at the planetary terminator. We compare the transmission spectrum with hot-Jupiter atmospheric models including condensate-free and aerosol-dominated models incorporating Mie theory. While none of the clear-atmosphere models is found to be in good agreement with the data, we find that the complete spectrum can be described by models that include significant opacity from aerosols including Fe-poor Mg 2 SiO 4 , MgSiO 3 , KCl and Na 2 S dust condensates. WASP-6b is the second planet after HD 189733b which has equilibrium temperatures near ∼ 1200 K and shows prominent atmospheric scattering in the optical.

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Section: Mie Scattering Dustmentioning

confidence: 99%

HST hot-Jupiter transmission spectral survey: haze in the atmosphere of WASP-6b

Nikolov

Sing

Burrows

et al. 2014

Monthly Notices of the Royal Astronomical Society

152

142

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“…for Mg 2 SiO 4 , Draine & Lee (1984) and Laor & Draine (1993) for astronomical silicate, Montaner et al (1979), Khachai et al (2009) and Morley et al (2012) for Na 2 S, and Khare et al (1984) for tholin. To study the aerosol degeneracy due to Q ext alone, the vertical temperature profile and the radius of the planet at the bottom of the atmosphere are fixed to be T = T dayside and R p = R 0 .…”

Section: Aerosol Materialsmentioning

confidence: 99%

CONSTRAINING THE ATMOSPHERIC COMPOSITION OF THE DAY-NIGHT TERMINATORS OF HD 189733b: ATMOSPHERIC RETRIEVAL WITH AEROSOLS

Lee

Irwin

Fletcher

et al. 2014

ApJ

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A number of observations have shown that Rayleigh scattering by aerosols dominates the transmission spectrum of HD 189733b at wavelengths shortward of 1 µm. In this study, we retrieve a range of aerosol distributions consistent with transmission spectroscopy between 0.3-24 µm that were recently re-analyzed by Pont et al. (2013). To constrain the particle size and the optical depth of the aerosol layer, we investigate the degeneracies between aerosol composition, temperature, planetary radius, and molecular abundances that prevent unique solutions for transit spectroscopy. Assuming that the aerosol is composed of MgSiO 3 , we suggest that a vertically uniform aerosol layer over all pressures with a monodisperse particle size smaller than about 0.1 µm and an optical depth in the range 0.002-0.02 at 1 µm provides statistically meaningful solutions for the day/night terminator regions of HD 189733b. Generally, we find that a uniform aerosol layer provide adequate fits to the data if the optical depth is less than 0.1 and the particle size is smaller than 0.1 µm, irrespective of the atmospheric temperature, planetary radius, aerosol composition, and gaseous molecules. Strong constraints on the aerosol properties are provided by spectra at wavelengths shortward of 1 µm as well as longward of 8 µm, if the aerosol material has absorption features in this region. We show that these are the optimal wavelengths for quantifying the effects of aerosols, which may guide the design of future space observations. The present investigation indicates that the current data offer sufficient information to constrain some of the aerosol properties of HD189733b, but the chemistry in the terminator regions remains uncertain.

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“…On the other hand, due to its simple form the WC functional is not flexible enough to accurately determine total exchange-correlation energy and its charge derivative. For this reason the modified GGA form of Engel and Vosko [20] (EV) GGA functional (that produces more accurate exchange-correlation potential at the expense of less accurate exchange energy) can be utilized; that has resulted in providing improved electronic band structure calculations for alkali metal oxides [21] and sulfides [22].…”

Section: Calculational Details and Structural Optimizationmentioning

confidence: 99%