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We study the incidence of magnetism in white dwarfs from three large and well-observed samples of hot, cool, and nearby white dwarfs in order to test whether the fraction of magnetic degenerates is biased, and whether it varies with…

Astrophysics · Physics 2009-11-07 James Liebert , P. Bergeron , J. B. Holberg

The evolution of white dwarfs is essentially a cooling process that depends primarily on the energy stored in their degenerate cores and on the transparency of their envelopes. In this paper we compute accurate cooling sequences for…

Astrophysics · Physics 2009-10-31 M. Salaris , E. Garcia-Berro , M. Hernanz , J. Isern , D. Saumon

We present new white dwarf cooling models which incorporate an accurate outer boundary condition based on new opacity and detailed radiative transfer calculations. We find that helium atmosphere dwarfs cool considerably faster than has…

Astrophysics · Physics 2011-02-11 Brad M. S. Hansen

The white dwarf luminosity function is well understood in terms of standard model physics and leaves little room for exotic cooling mechanisms related to the possible existence of new weakly interacting light particles. This puts…

High Energy Physics - Phenomenology · Physics 2015-06-17 Lorenzo Ubaldi

About 20% of the white dwarfs possess a magnetic field that may be detected by the splitting and/or polarization of their spectral lines. As they cool, the effective temperatures of the white dwarfs becomes so low that no spectral lines can…

Solar and Stellar Astrophysics · Physics 2024-08-08 A. Berdyugin , J. D. Landstreet , S. Bagnulo , V. Piirola , S. V. Berdyugina

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

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

The observed correlations, between the characteristic ages and dipole surface magnetic field strengths of all pulsars, can be well explained by magnetic field decay with core temperatures of $~2\times10^{8}$ K, $\sim2\times10^{7}$ K, and…

High Energy Astrophysical Phenomena · Physics 2011-10-19 Yi Xie , Shuang-Nan Zhang

Cooling of neutron stars with dipole magnetic fields is simulated using a realistic model of the anisotropic surface temperature distribution produced by magnetic fields. Suppression of the electron thermal conductivity of outer stellar…

Astrophysics · Physics 2011-05-23 Yu. A. Shibanov , D. G. Yakovlev

We study the thermal structure and evolution of magnetars as cooling neutron stars with a phenomenological heat source in an internal layer. We focus on the effect of magnetized (B > 10^{14} G) non-accreted and accreted outermost envelopes…

Solar and Stellar Astrophysics · Physics 2009-05-20 A. D. Kaminker , A. Y. Potekhin , D. G. Yakovlev , G. Chabrier

In recent years a number of white dwarfs has been observed with very high surface magnetic fields. We can expect that the magnetic field in the core of these stars would be much higher (~ 10^{14} G). In this paper, we analytically study the…

Solar and Stellar Astrophysics · Physics 2012-05-09 Aritra Kundu , Banibrata Mukhopadhyay

The presence of a strong magnetic field is a feature common to a significant fraction of degenerate stars, yet little is understood about field origin and evolution. New observational constraints from volume-limited surveys point to a more…

Solar and Stellar Astrophysics · Physics 2022-08-24 Stefano Bagnulo , John D. Landstreet

In recent times, astounding observations of both over- and under-luminous type Ia supernovae have emerged. These peculiar observations hint not only at surpassing the Chandrasekhar limit but may also suggest potential modifications in the…

General Relativity and Quantum Cosmology · Physics 2024-05-16 Snehasish Bhattacharjee

Neutron stars cool down during their lifetime through the combination of neutrino emission from the interior and photon cooling from the surface. Strongly magnetised neutron stars, called magnetars, are no exception, but the effect of their…

High Energy Astrophysical Phenomena · Physics 2023-01-18 Clara Dehman , José A. Pons , Daniele Viganò , Nanda Rea

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

The evolution of the magnetic field of an accreting magnetic white dwarf with an initially dipolar field at the surface has been studied for non-spherical accretion under simplifying assumptions. Accretion on to the polar regions tends to…

High Energy Astrophysical Phenomena · Physics 2015-05-13 C. M. Zhang , D. T. Wickramasinghe , L. Ferrario

We describe a new survey for cool white dwarfs that supplements Sloan Digital Sky Survey photometry with USNO proper motions and follow-up spectroscopy. To date we have discovered and spectroscopically confirmed 80 new moderate temperature…

Using a new grid of models of cooling white dwarfs, we calculate isochrones and luminosity functions in the Johnson-Kron/Cousins and HST filter sets for systems containing old white dwarfs. These new models incorporate a non-grey atmosphere…

In a volume-limited sample of 63 ultracool dwarfs of spectral type M7-M9.5, we have obtained high-resolution spectroscopy with UVES at the Very Large Telescope and HIRES at Keck Observatory. In this second paper, we present projected…

Solar and Stellar Astrophysics · Physics 2014-11-20 Ansgar Reiners , Gibor Basri

It has been shown that the shape of the luminosity function of white dwarfs can be a powerful tool to check for the possible existence of DFSZ-axions. In particular, Isern et al. (2008) showed that, if the axion mass is of the order of a…

High Energy Physics - Phenomenology · Physics 2012-10-02 Brenda Melendez , Marcelo Miller Bertolami , Leandro Althaus