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The influence of strong, large-scale magnetic fields on the structure and temperature distribution in white dwarf atmospheres is investigated. Magnetic fields may provide an additional component of pressure support, thus possibly inflating…

Astrophysics · Physics 2016-08-30 Ch. Fendt , D. Dravins

We present an homogeneous analysis of all DA stars labeled as magnetic in the Montreal White Dwarf Database (MWDD). Our sample is restricted to almost all known magnetic white dwarf showing clear sign of splitting ($B \gtrsim$ 1-2 MG) that…

Solar and Stellar Astrophysics · Physics 2023-02-01 François Hardy , Patrick Dufour , Stefan Jordan

We present an analysis of all single white dwarf stars known to exhibit spectroscopic signatures of neutral helium line splitting due to the presence of a strong magnetic field. Using state-of-the-art models taking into account the effects…

Solar and Stellar Astrophysics · Physics 2023-02-01 François Hardy , Patrick Dufour , Stefan Jordan

The photospheres of the coolest helium-atmosphere white dwarfs are characterized by fluid-like densities. Under those conditions, standard approximations used in model atmosphere codes are no longer appropriate. Unfortunately, the majority…

Solar and Stellar Astrophysics · Physics 2018-08-29 Simon Blouin , Patrick Dufour , Nicole F. Allard

White dwarfs are excellent research laboratories as they reach temperatures, pressures, and magnetic fields that are unattainable on Earth. To better understand how these three physical parameters interact with each other and with other…

Solar and Stellar Astrophysics · Physics 2023-02-22 L. L. Amorim , S. O. Kepler , Baybars Külebi , S. Jordan , A. D. Romero

In this work, we study the effects of temperature on magnetic white dwarfs. We model their interior as a nuclei lattice surrounded by a relativistic free Fermi gas of electrons, accounting for effects from temperature, Landau levels and…

Solar and Stellar Astrophysics · Physics 2021-11-03 J. Peterson , V. Dexheimer , R. Negreiros , B. G. Castanheira

We assess the partition function and ionization degree of magnetized hydrogen atoms at thermodynamic equilibrium for a wide range of field intensities, $B\approx 10^5$-$10^{12}$~G. Evaluations include fitting formulae for an arbitrary…

Solar and Stellar Astrophysics · Physics 2020-04-01 Matías Vera Rueda , René D. Rohrmann

We present extensive and accurate calculations for the excited state spectrum of spin-polarized neutral helium in a range of magnetic field strengths up to $10^{12}$ G. Of considerable interest to models of magnetic white dwarf stellar…

Atomic Physics · Physics 2009-10-31 Matthew D. Jones , Gerardo Ortiz , David M. Ceperley

Using our newly developed model atmosphere code appropriate for magnetic white dwarfs with metal lines in the Paschen-Back regime, we study various magnetic white dwarfs and explore the effects of various parameters such as the field…

Solar and Stellar Astrophysics · Physics 2016-10-06 François Hardy , Patrick Dufour , Stefan Jordan

We present a detailed calculation of model atmospheres for DA white dwarfs. Our atmosphere code solves the atmosphere structure in local thermodynamic equilibrium with a standard partial linearization technique, which takes into account the…

Astrophysics · Physics 2015-06-24 R. D. Rohrmann

We have computed optical Zeeman spectra of magnetic white dwarfs for field strengths between 10 and 200MG and effective temperatures between 8000 and 40000K. They form a database containing 20628 sets of flux and circular polarization…

Astrophysics · Physics 2007-05-23 F. Euchner , S. Jordan , K. Beuermann , B. T. Gaensicke , F. V. Hessmann

We construct hydrogen atmosphere models for magnetized neutron stars in radiative equilibrium with surface fields B=10^12-5x10^14 G and effective temperatures T_eff a few x 10^5-10^6 K by solving the full radiative transfer equations for…

Astrophysics · Physics 2009-11-07 Wynn C. G. Ho , Dong Lai , Alexander Y. Potekhin , Gilles Chabrier

Our ongoing spectroscopic survey of high proper motion stars is a rich source of new magnetic white dwarfs. We present a few examples among cool white dwarfs showing the effect of field strength and geometry on the observed optical…

Solar and Stellar Astrophysics · Physics 2018-01-18 S. Vennes , A. Kawka , L. Ferrario , E. Paunzen

We construct models for strongly-magnetized neutron star atmospheres composed of mid-Z elements (carbon, oxygen and neon) with magnetic fields B=10^{12}-10^{13} G and effective temperatures Teff=(1-5)*10^6 K; this is done by first…

Astrophysics · Physics 2008-11-26 Kaya Mori , Wynn C. G. Ho

Observed X-ray spectra of some isolated magnetized neutron stars display absorption features, sometimes interpreted as ion cyclotron lines. Modeling the observed spectra is necessary to check this hypothesis and to evaluate neutron star…

Solar and Stellar Astrophysics · Physics 2009-07-03 V. F. Suleimanov , A. Y. Potekhin , K. Werner

We present a new computer code for modeling magnetized neutron star atmospheres in a wide range of magnetic fields (10^{12} - 10^{15} G) and effective temperatures (3 \times 10^5 - 10^7 K). The atmosphere is assumed to consist either of…

High Energy Astrophysical Phenomena · Physics 2010-11-23 V. Suleimanov , A. Y. Potekhin , K. Werner

To obtain a better statistics on the occurrence of magnetism among white dwarfs, we searched the spectra of the hydrogen atmosphere white dwarf stars (DAs) in the Data Release 7 of the Sloan Digital Sky Survey (SDSS) for Zeeman splittings…

Complete modeling of radiative transfer in neutron star atmospheres is in progress, taking into account the anisotropy induced by magnetic fields, non-ideal effects and general relativity. As part of our modeling, we present a novel atomic…

Astrophysics · Physics 2009-11-07 Kaya Mori , Charles J. Hailey

White dwarf atmospheres are subjected to gravitational potentials around $10^5$ times larger than occur on Earth. They provide a unique environment in which to search for any possible variation in fundamental physics in the presence of…

We present a detailed investigation of neutron star atmospheres with low magnetic fields, $B < 10^8 -10^{10}$ G, which do not affect opacities and equation of state of the atmospheric matter. We compute the atmospheric structure, emergent…

Astrophysics · Physics 2007-05-23 V. E. Zavlin , G. G. Pavlov , Yu. A. Shibanov
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