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Non-LTE line-blanketed model atmospheres of hot stars. 1: Hybrid complete linearization/accelerated lambda iteration method
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Non‑LTE line‑blanketed model atmospheres are essential for accurately modeling hot stars, yet existing computational methods are often prohibitively demanding. The authors introduce a hybrid complete linearization/accelerated lambda iteration method to efficiently compute non‑LTE line‑blanketed model atmospheres for hot stars. The method blends complete linearization with accelerated lambda iteration, treating most frequency points via ALI while explicitly linearizing a few, and employs superlevels and superlines to handle metal line blanketing. The hybrid CL/ALI achieves convergence comparable to full CL while reducing per‑iteration time to near that of ALI, and it reliably produces robust non‑LTE line‑blanketed models across a broad range of stellar parameters. Published in The Astrophysical Journal (Feb 1995, DOI 10.1086/175226) with source code available at 2011ascl.soft09021H.
view Abstract Citations (1120) References (48) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Non-LTE Line-blanketed Model Atmospheres of Hot Stars. I. Hybrid Complete Linearization/Accelerated Lambda Iteration Method Hubeny, I. ; Lanz, T. Abstract A new munerical method for computing non-Local Thermodynamic Equilibrium (non-LTE) model stellar atmospheres is presented. The method, called the hybird complete linearization/accelerated lambda iretation (CL/ALI) method, combines advantages of both its constituents. Its rate of convergence is virtually as high as for the standard CL method, while the computer time per iteration is almost as low as for the standard ALI method. The method is formulated as the standard complete lineariation, the only difference being that the radiation intensity at selected frequency points is not explicity linearized; instead, it is treated by means of the ALI approach. The scheme offers a wide spectrum of options, ranging from the full CL to the full ALI method. We demonstrate that the method works optimally if the majority of frequency points are treated in the ALI mode, while the radiation intensity at a few (typically two to 30) frequency points is explicity linearized. We show how this method can be applied to calculate metal line-blanketed non-LTE model atmospheres, by using the idea of 'superlevels' and 'superlines' introduced originally by Anderson (1989). We calculate several illustrative models taking into accont several tens of thosands of lines of Fe III to Fe IV and show that the hybrid CL/ALI method provides a robust method for calculating non-LTE line-blanketed model atmospheres for a wide range of stellar parameters. The results for individual stellar types will be presented in subsequent papers in this series. Publication: The Astrophysical Journal Pub Date: February 1995 DOI: 10.1086/175226 Bibcode: 1995ApJ...439..875H Keywords: Hot Stars; Iterative Solution; Numerical Analysis; Radiative Transfer; Stellar Atmospheres; Stellar Models; Absorptivity; Equilibrium Equations; Jacobi Matrix Method; Line Spectra; Linearization; Newton-Raphson Method; Astrophysics; METHODS: NUMERICAL; RADIATIVE TRANSFER; STARS: ATMOSPHERES; STARS: EARLY-TYPE full text sources ADS | Related Materials (3) Part 2: 1995ApJ...439..905L Part 3: 1997ApJ...485..843L Source Software: 2011ascl.soft09021H