Abstract
White dwarfs with magnetic field strengths larger than 10 T are understood to represent more than 10% of the total population of white dwarfs. The presence of such strong magnetic fields is clearly indicated by the Zeeman triplet structure visible on absorption lines. In this work, we discuss the line broadening mechanisms and focus on the sensitivity of hydrogen lines on the magnetic field. We perform new calculations in conditions relevant to magnetized DA stellar atmospheres using models inspired from magnetic fusion plasma spectroscopy. A white dwarf spectrum from the Sloan Digital Sky Survey (SDSS) database is analyzed. An effective temperature is provided by an adjustment of the background radiation with a Planck function, and the magnetic field is inferred from absorption lines presenting a Zeeman triplet structure. An order-of-magnitude estimate for the electron density is also performed from Stark broadening analysis.
Highlights
White dwarfs—the end products of stellar evolution—occupy a key position in astrophysical theory
We report on the current status of the design of a line shape model accounting for Stark and Zeeman effects simultaneously, for applications to white dwarf atmosphere analysis
The applicability of spectroscopy as a diagnostic means is illustrated through the analysis of a white dwarf spectrum obtained from the Sloan Digital Sky Survey (SDSS) database
Summary
White dwarfs—the end products of stellar evolution—occupy a key position in astrophysical theory. Studies of white dwarf atmospheres have shown that the majority of white dwarfs have an atmosphere of pure hydrogen as a result of gravitational setting, which removes helium and heavier elements from the atmosphere and moves them towards inner layers [5,6] These atmospheres can be considered as hydrogen plasmas, which are similar to some created in laboratory. Zeeman component due to the change of the atomic energy level structure (degeneracy removal) in response to an external magnetic field [7,8] This issue concerns magnetized white dwarfs with spectra exhibiting Zeeman splitting. The applicability of spectroscopy as a diagnostic means is illustrated through the analysis of a white dwarf spectrum obtained from the Sloan Digital Sky Survey (SDSS) database
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