Radiative Transfer with Opacity Distribution Functions: Application to Narrowband Filters

Anusha, L. S.; Шапиро, А. И.; Witzke, V.; Černetič, Miha; Solanki, S. K.; Gizon, Laurent

doi:10.3847/1538-4365/abfb72

Cited by 7 publications

(3 citation statements)

References 29 publications

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“…edu/programs/NEWDF/, accessed on 13 April 2011) [44]. The code has been recently used to produce an extensive grid of 1D stellar atmospheres and spectra [28], as well as to calculate emergent 3D atmospheric irradiance models [45,46]. Here, we present only calculations based on 1D modeling when the atmospheric structure and emergent spectrum are calculated with the MPS-ATLAS code.…”

Section: Methodology For Obtaining the Mps-atlas Solar Spectra Based ...mentioning

confidence: 99%

The SOLAR-HRS New High-Resolution Solar Spectra for Disk-Integrated, Disk-Center, and Intermediate Cases

et al. 2023

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The solar spectrum at the top of the atmosphere contains crucial data for solar physics, astronomy, and geophysics. Accurately determining high-resolution solar reference spectra, whether they are disk-integrated, disk-center, or intermediate cases, represents a new challenge and is of primary importance for all applications where spectral solar radiation needs to be evaluated. These spectra are also essential for interpreting remote sensing measurements that rely on sunlight, such as those obtained by Earth observation satellites or spacecraft exploring other planets. This paper lays a foundation for the implementation of multiple new solar irradiance reference spectra that have high resolution and are representative of solar minimum conditions. We developed the SOLAR high-resolution extraterrestrial reference spectra (SOLAR-HRS disk-integrated spectra) by normalizing high-spectral-resolution solar line data to the absolute irradiance scale of the SOLAR-ISS reference spectrum. The resulting one-of-a-kind SOLAR-HRS disk-integrated spectrum has a spectral resolution varying between 0.001 and 1 nm in the 0.5–4400 nm wavelength range. We also implemented a new high-resolution solar spectrum at the disk-center, covering a range of 650–4400 nm with a spectral resolution of 0.001 to 0.02 nm. We further expanded our analysis by producing several solar spectra for ten different solar view angles ranging from μ = 0.9 to μ = 0.05 (SOLAR-HRS intermediate cases). Finally, we developed new Merged Parallelised Simplified ATLAS spectra (MPS-ATLAS) based on solar modeling with Kurucz and Vald3 solar linelists for both the disk-integrated and disk-center spectra. One of the objectives of implementing all these new solar spectra is to fulfill the requirements of the MicroCarb space mission, which focuses on measuring greenhouse gas emissions. The solar data of this study are openly available.

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Section: Methodology For Obtaining the Mps-atlas Solar Spectra Based ...mentioning

confidence: 99%

The SOLAR-HRS New High-Resolution Solar Spectra for Disk-Integrated, Disk-Center, and Intermediate Cases

et al. 2023

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“…MPS-ATLAS has been intensively tested against solar and stellar observations and incorporates improved molecular and atomic data (Witzke et al 2021;Kostogryz et al 2022). It incorporates the implementation of the optimized opacity distribution functions (ODF, Cernetic et al 2019;Anusha et al 2021) as well as MPI parallelization, which allowed us to perform calculations on a fine grid of stellar fundamental parameters. Kostogryz et al (2022) presented a new stellar limb darkening library which demonstrates excellent agreement with available solar (Neckel & Labs 1994) and stellar data Maxted (2018Maxted ( , 2023.…”

Section: Atmospheric Models and Stellar Spectramentioning

confidence: 99%

MPS-ATLAS library of stellar model atmospheres and spectra

Kostogryz¹,

Shapiro²,

Witzke³

et al. 2023

Preprint

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Stellar spectra contain a large amount of information about the conditions in stellar atmospheres. However, extracting this information is challenging and demands comprehensive numerical modelling. Here, we present stellar spectra synthesized using the recently developed stateof-the-art MPS-ATLAS code on a fine grid of stellar fundamental parameters. These calculations have been extensively validated against solar and stellar observations and can be used for various astrophysical applications. The spectra are available at the Max Planck Digital Library (MPDL, https://edmond.mpdl.mpg.de/dataset.xhtml?persistentId=doi:10.17617/3.NJ56TR) and have been also incorporated into the ExoTiC-LD python package (https://github.com/Exo-TiC/ExoTiC-LD/ which returns stellar limb darkening coefficients used for the software package Exoplanet Timeseries Characterisation (ExoTic).

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“…However, it will not be able to handle line transport easily without a large number of frequency groups. One special type of multigroup RT uses the so-called opacity distribution function method, which divides the frequency space based on the ordering of opacity as a function of frequency (Skartlien 2000;Anusha et al 2021;Witzke et al 2021). It can be used to handle strong opacity variations as a function of frequency efficiently.…”

Section: Introductionmentioning

confidence: 99%

Multigroup Radiation Magnetohydrodynamics Based on Discrete Ordinates including Compton Scattering

Jiang

2022

ApJS

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We present a formulation and numerical algorithm to extend the scheme for gray radiation magnetohydrodynamics (MHD) developed by Jiang to include the frequency dependence via the multigroup approach. The entire frequency space can be divided into an arbitrary number of groups in the lab frame, and we follow the time-dependent evolution of frequency-integrated specific intensities along discrete rays inside each group. Spatial transport of photons is done in the lab frame while all the coupling terms are solved in the fluid rest frame. Lorentz transformation is used to connect different frames. The radiation transport equation is solved fully implicitly in time while the MHD equations are evolved explicitly so that time step is not limited by the speed of light. A finite volume approach is used for transport in both spatial and frequency spaces to conserve the radiation energy density and momentum. The algorithm includes photon absorption, electron scattering, as well as Compton scattering, which is calculated by solving the Kompaneets equation. The algorithm is accurate for a wide range of optical depth conditions and can handle both radiation-pressure- and gas-pressure-dominated flows. It works for both Cartesian and curvilinear coordinate systems with adaptive mesh refinement. We provide a variety of test problems including a radiating sphere, shadow test, absorption of a moving gas, Bondi-type flows, as well as a collection of test problems for thermal and bulk Compton scattering. We also discuss examples where frequency dependence can make a big difference compared with the gray approach.

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Radiative Transfer with Opacity Distribution Functions: Application to Narrowband Filters

Cited by 7 publications

References 29 publications

The SOLAR-HRS New High-Resolution Solar Spectra for Disk-Integrated, Disk-Center, and Intermediate Cases

The SOLAR-HRS New High-Resolution Solar Spectra for Disk-Integrated, Disk-Center, and Intermediate Cases

MPS-ATLAS library of stellar model atmospheres and spectra

Multigroup Radiation Magnetohydrodynamics Based on Discrete Ordinates including Compton Scattering

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