On the transient radiative transfer in a one-dimensional planar medium subjected to radiative equilibrium

Exoplanets with substantial hydrogen/helium atmospheres have been discovered in abundance, many residing extremely close to their parent stars. The extreme irradiation levels that these atmospheres experience cause them to undergo hydrodynamic atmospheric escape. Ongoing atmospheric escape has been observed to be occurring in a few nearby exoplanet systems through transit spectroscopy both for hot Jupiters and for lower-mass super-Earths and mini-Neptunes. Detailed hydrodynamic calculations that incorporate radiative transfer and ionization chemistry are now common in one-dimensional models, and multidimensional calculations that incorporate magnetic fields and interactions with the interstellar environment are cutting edge. However, comparison between simulations and observations remains very limited. While hot Jupiters experience atmospheric escape, the mass-loss rates are not high enough to affect their evolution. However, for lower-mass planets, atmospheric escape drives and controls their evolution, sculpting the exoplanet population that we observe today. ▪ Observations of some exoplanets have detected atmospheric escape driven by hydrodynamic outflows, causing the exoplanets to lose mass over time. ▪ Hydrodynamic simulations of atmospheric escape are approaching the sophistication required to compare them directly to observations. ▪ Atmospheric escape sculpts sharp features into the exoplanet population that we can observe today; these features have recently been detected.

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Radiative transfer in a one-dimensional fluctuating albedo mixture

10.1063/1.46917 ◽

1994 ◽

Author(s):

Daniel Vanderhaegen ◽

Claude Deutsch ◽

Patrick Boissé

Keyword(s):

Radiative Transfer ◽

One Dimensional

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Understanding nebular spectra of Type Ia supernovae

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa640 ◽

2020 ◽

Vol 494 (2) ◽

pp. 2221-2235 ◽

Cited By ~ 2

Author(s):

Kevin D Wilk ◽

D John Hillier ◽

Luc Dessart

Keyword(s):

Radiative Transfer ◽

Local Thermodynamic Equilibrium ◽

Diagnostic Feature ◽

Type Ia Supernovae ◽

Thermal Heating ◽

One Dimensional ◽

Type Ia ◽

Natural Mechanism ◽

Non Local ◽

Ia Supernovae

ABSTRACT In this study, we present one-dimensional, non-local-thermodynamic-equilibrium, radiative transfer simulations (using cmfgen) in which we introduce micro-clumping at nebular times into two Type Ia supernova ejecta models. We use one sub-Chandrasekhar (sub-MCh) ejecta model with 1.04 M⊙ and one Chandrasekhar (MCh) ejecta model with 1.40 M⊙. We introduce clumping factors f = 0.33, 0.25, and 0.10, which are constant throughout the ejecta, and compare results to the unclumped f = 1.0 case. We find that clumping is a natural mechanism to reduce the ionization of the ejecta, reducing emission from [Fe iii], [Ar iii], and [S iii] by a factor of a few. For decreasing values of the clumping factor f, the [Ca ii] λλ7291,7324 doublet became a dominant cooling line for our MCh model but remained weak in our sub-MCh model. Strong [Ca ii] λλ7291,7324 indicates non-thermal heating in that region and may constrain explosion modelling. Due to the low abundance of stable nickel, our sub-MCh model never showed the [Ni ii] 1.939-μm diagnostic feature for all clumping values.

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The SKN Approximation for Solving Radiative Transfer Problems in Absorbing, Emitting, and Isotropically Scattering Plane-Parallel Medium: Part 1

Journal of Heat Transfer ◽

10.1115/1.1464130 ◽

2002 ◽

Vol 124 (4) ◽

pp. 674-684 ◽

Cited By ~ 13

Author(s):

Zekeriya Altac¸

Keyword(s):

Integral Equation ◽

Radiative Transfer ◽

Differential Equations ◽

Order Approximation ◽

High Order ◽

High Order Approximation ◽

One Dimensional ◽

Second Order Differential Equations ◽

Plane Parallel ◽

Transfer Problems

A high order approximation, the SKN method—a mnemonic for synthetic kernel—is proposed for solving radiative transfer problems in participating medium. The method relies on approximating the integral transfer kernel by a sum of exponential kernels. The radiative integral equation is then reducible to a set of coupled second-order differential equations. The method is tested for one-dimensional plane-parallel participating medium. Three quadrature sets are proposed for the method, and the convergence of the method with the proposed sets is explored. The SKN solutions are compared with the exact, PN, and SN solutions. The SK1 and SK2 approximations using quadrature Set-2 possess the capability of solving radiative transfer problems in optically thin systems.

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Three Dimensional Radiative Transfer in ICON-LEM

10.5194/egusphere-egu2020-16687 ◽

2020 ◽

Author(s):

Fabian Jakub ◽

Bernhard Mayer

Keyword(s):

Radiative Transfer ◽

Detrimental Effect ◽

Energy Transport ◽

Three Dimensional ◽

Cloud Formation ◽

One Dimensional ◽

3D Effects ◽

Computational Simplicity ◽

Boundary Layer Dynamics ◽

Side Illumination

<pre class="moz-quote-pre">Recent studies have shown that the effects of three dimensional radiative transfer may impact cloud formation and precipitation. While one-dimensional solvers are favoured due to their computational simplicity, they do however neglect any horizontal energy transport. In particular, the 1D approximation neglects 3D effects such as cloud side illumination and the displacement of the cloud's shadow at the surface which are relevant whenever the sun is not in the zenith. This has a detrimental effect on the results of high resolution simulations. 3D radiative transfer has the potential to considerably change the boundary layer dynamics, the evolution of clouds, their lifetime and precipitation onset. To this date, studies that investigate the influence of 3D effects on realistic NWP settings are rare, primarily because there haven't been 3D radiative transfer solvers around that were fast enough to be run interactively in a forecast simulation. For that purpose we adapted the TenStream solver (parallel 3D radiative transfer solver for LES) to unstructured meshes and coupled it to ICON-LEM. We will present the new solver in the context of ICON-LEM simulations, the methodologies used and its characteristics.</pre>

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