SolRaT: Introduction

SolRaT (Solar Radiative Transfer) is a flexible, forward-modeling, non-LTE radiative transfer code for stellar atmospheres. It implements the statistical equilibrium and radiative transfer equations within the multi-term atom model, enabling detailed synthesis of Stokes profiles in magnetic fields of arbitrary strength, from the Zeeman to the Paschen-Back regimes.

Model of He I D3 emission in a limb event under different magnetic fields

Key Features

  • Physics: Solves non-LTE radiative transfer for multi-term atoms.

  • Magnetic Fields: Handles arbitrary magnetic field strengths (Zeeman, Hanle, Paschen-Back effects).

  • Atmosphere: Supports multi-slab atmospheres for height stratification under anisotropic illumination (ATL08, HAZEL2).

  • Flexibility: Provides a high-level meta-language allowing you to write code that directly resembles the underlying mathematical equations.

  • Accessibility: SolRaT is free, open-source, and platform-independent.

  • Performance: SolRaT uses high-performance libraries that leverage SIMD instruction sets.

  • Extensibility: A clear Modeling API allows for quick prototyping and model adjustments for specific contexts.

The figure above demonstrates a sample output: the modeling of He I D3 emission under varying magnetic field strengths.

The code provides a multi-level framework for modeling radiative transfer:

  • Public API allows to run built-in RT models. Currently, SolRaT ships the non-LTE multi-term atom model (LL04) with multiple constant-slab atmosphere stratification.

  • Modeling API allows to extend existing models or create completely new ones.

  • SolRaT Engine introduces a meta-language that allows the user to write a human-readable code that directly resembles the underlying mathematical equations. The user does not need to focus on code optimization, as it is handled under the hood.

[LL04] Landi Degl’Innocenti, E., & Landolfi, M. 2004, Polarization in Spectral Lines (Dordrecht: Kluwer)

[ATL08] Asensio Ramos, A., Trujillo Bueno, J., & Landi Degl’Innocenti, E. (2008). Advanced Forward Modeling and Inversion of Stokes Profiles Resulting from the Joint Action of the Hanle and Zeeman Effects. The Astrophysical Journal, 683(1), 542–565.

[HAZEL2] [Link](https://github.com/aasensio/hazel2)

How to Cite

If SolRaT contributes to your research, please cite it as:

Yakovkin I. I. SolRaT (2023) [computer software]. Retrieved from https://www.yakovkinii.com/solrat/

Installation

Install the latest release from PyPI:

pip install solrat

For the development version, clone the repository and install in editable mode:

git clone https://github.com/yakovkinii/SolRaT.git
cd SolRaT
pip install -e .

Next

Check out the Quick Start & Examples guide for basic usage examples.