scholarly journals Non-local Thermodynamic Equilibrium Radiative Transfer Simulations of Sub-Chandrasekhar-mass White Dwarf Detonations

2021 ◽  
Vol 909 (2) ◽  
pp. L18
Author(s):  
Ken J. Shen ◽  
Stéphane Blondin ◽  
Daniel Kasen ◽  
Luc Dessart ◽  
Dean M. Townsley ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Thermodynamic Equilibrium ◽  
White Dwarf ◽  
Local Thermodynamic Equilibrium ◽  
Non Local

scholarly journals H and He in stripped-envelope SNe – how much can be hidden?

2011 ◽  
Vol 7 (S279) ◽  
pp. 122-125
Author(s):  
S. Hachinger ◽  
P. A. Mazzali ◽  
S. Taubenberger ◽  
W. Hillebrandt ◽  
K. Nomoto ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Thermodynamic Equilibrium ◽  
Stellar Evolution ◽  
Local Thermodynamic Equilibrium ◽  
Explosion Energy ◽  
High Mass ◽  
Synthetic Spectra ◽  
Non Local ◽  
Moderate Mass

AbstractH and He features in photospheric spectra have rarely been used to constrain the structure of Type IIb/Ib/Ic supernovae (SNe IIb/Ib/Ic). The lines have to be modelled with a detailed non-local-thermodynamic-equilibrium (NLTE) treatment, including effects uncommon in stars. Once this is done, however, one obtains valuable hints on the characteristics of progenitors and explosions (composition, explosion energy, . . .). We have extended a radiative transfer code to compute synthetic spectra of SNe IIb, Ib and Ic. Here, we discuss our first larger set of models, focusing on the question: How much H/He can be hidden (i.e. remain undetected in photospheric spectra) in SNe Ib/Ic? For the SNe studied (relatively low Mej = 1. . .3 M⊙), we find a limit of MHe ≲ 0.1 M⊙ in SNe Ic (no unambiguous He lines). Stellar evolution models for single stars normally always yield higher masses. We suggest that low- or moderate-mass SNe Ic result from efficient envelope stripping in binaries. We propose similar studies on H/He in high-mass and extremely aspherical SNe, and observations covering the region of He I λ 20581.

scholarly journals kCARTA: a fast pseudo line-by-line radiative transfer algorithm with analytic Jacobians, fluxes, nonlocal thermodynamic equilibrium, and scattering for the infrared

2020 ◽  
Vol 13 (1) ◽  
pp. 323-339 ◽  
Author(s):  
Sergio DeSouza-Machado ◽  
L. Larrabee Strow ◽  
Howard Motteler ◽  
Scott Hannon
Keyword(s):  
Radiative Transfer ◽  
Thermodynamic Equilibrium ◽  
Local Thermodynamic Equilibrium ◽  
Singular Value ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Clear Sky ◽  
Non Local ◽  
Value Decomposition ◽  
Current Database

Abstract. A fast pseudo-monochromatic radiative transfer package using a singular value decomposition (SVD) compressed atmospheric optical depth database has been developed, primarily for simulating radiances from hyperspectral sounding instruments (resolution ≥0.1 cm−1). The package has been tested extensively for clear-sky radiative transfer cases, using field campaign data and satellite instrument data. The current database uses HITRAN 2016 line parameters and is primed for use in the spectral region spanning 605 to 2830 cm−1. Optical depths for other spectral regions (15–605 and 2830–45 000 cm−1) can also be generated for use by kCARTA. The clear-sky radiative transfer model computes the background thermal radiation quickly and accurately using a layer-varying diffusivity angle at each spectral point; it takes less than 30 s (on a 2.8 GHz core using four threads) to complete a radiance calculation spanning the infrared. The code can also compute non-local thermodynamic equilibrium effects for the 4 µm CO2 region, as well as analytic temperature, gas and surface Jacobians. The package also includes flux and heating rate calculations and an interface to an infrared scattering model.

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