Method and new tabulations for flux-weighted line-opacity and radiation line-force in supersonic media

Abstract

In accelerating and supersonic media, the interaction of photons with spectral lines can be of ultimate importance. However, fully accounting for such line forces currently can only be done by specialised codes in 1-D steady-state flows. More general cases and higher dimensions require alternative approaches. We presented a comprehensive and fast method for computing the radiation line-force using tables of spectral line-strength distribution parameters, which can be applied in arbitrary (multi-D, time-dependent) simulations, including those accounting for the line-deshadowing instability, to compute the appropriate opacities. We assumed local thermodynamic equilibrium to compute a flux-weighted line opacity from $>4$ million spectral lines. We derived the spectral line strength and tabulated the corresponding line-distribution parameters for a range of input densities $\rho \in [10^{-20},10^{-10}]gc{m}^{-3}$ and temperatures $T\in [10^4,10^{4.7}]K$. We found that the variation of the line distribution parameters plays an essential role in setting the wind dynamics in our models. In our benchmark study, we also found a good overall agreement between the O-star mass-loss rates of our models and those derived from steady-state studies using more detailed radiative transfer. Our models reinforce that self-consistent variation of the line-distribution parameters is important for the dynamics of line-driven flows. Within a well-calibrated O-star regime, our results support the proposed methodology. In practice, utilising the provided tables, yielded a factor $>100$ speed-up in computational time compared to specialised 1-D model-atmosphere codes of line-driven winds, which constitutes an important step towards efficient multi-D simulations. We conclude that our method and tables are ready to be exploited in various radiation-hydrodynamic simulations where the line force is important.

References in corpus (15)

• Mass loss from hot massive stars
• Theory and Diagnostics of Hot Star Mass Loss
• Numerical Simulations of Convective 3-Dimensional Red Supergiant Envelopes
• New predictions for radiation-driven, steady-state mass-loss and wind-momentum from hot, massive stars. I. Method and first results
• Winds of low-metallicity OB-type stars: HST-COS spectroscopy in IC1613
• First 3D Radiation-Hydrodynamic Simulations of Wolf-Rayet Winds
• Empirical mass-loss rates and clumping properties of Galactic early-type O supergiants
• Theoretical wind clumping predictions of OB supergiants from line-driven instability simulations across the bi-stability jump
• Instabilities in the Envelopes and Winds of Very Massive Stars
• Dynamically inflated wind models of classical Wolf-Rayet stars
• Radiation-Hydrodynamics with MPI-AMRVAC: Flux-Limited Diffusion
• An Updated Formalism For Line-Driven Radiative Acceleration and Implications for Stellar Mass Loss
• New hydrodynamic solutions for line-driven winds of hot massive stars using Lambert $W$-function
• Self-consistent solutions for line-driven winds of hot massive stars. The m-CAK procedure
• Simulations of the line-driven instability in magnetic hot star winds

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