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Atmospheric parameters for hot DB (helium atmosphere) white dwarfs near effective temperatures of 25000K are extremely difficult to determine from optical spectroscopy. This is particularly unfortunate, because this is the range of variable…

Solar and Stellar Astrophysics · Physics 2014-09-05 Detlev Koester , Judi Provencal , Boris T. Gänsicke

We investigate the luminosity and cooling of highly magnetized white dwarfs with electron-degenerate cores and non-degenerate surface layers where cooling occurs by diffusion of photons. We find the temperature and density profiles in the…

Solar and Stellar Astrophysics · Physics 2018-05-14 Mukul Bhattacharya , Banibrata Mukhopadhyay , Subroto Mukerjee

We present a new set of cooling models and isochrones for both H- and He-atmosphere white dwarfs, incorporating accurate boundary conditions from detailed model atmosphere calculations, and carbon-oxygen chemical abundance profiles based on…

Solar and Stellar Astrophysics · Physics 2015-05-18 M. Salaris , S. Cassisi , A. Pietrinferni , P. M. Kowalski , J. Isern

We present a spectro-photometric analysis of 2880 cool white dwarfs within 100 pc of the Sun and cooler than Teff = 10,000 K, with grizy Pan-STARRS photometry and Gaia trigonometric parallaxes available. We also supplement our data sets…

Solar and Stellar Astrophysics · Physics 2022-12-28 Alexandre Caron , Pierre Bergeron , Simon Blouin , Sandy K. Leggett

The purpose of this work is to explore the evolution of helium-core white dwarf stars in a self-consistent way with the predictions of detailed non-gray model atmospheres and element diffusion. To this end, we consider helium-core white…

Astrophysics · Physics 2009-11-06 A. M. Serenelli , L. G. Althaus , R. D. Rohrmann , O. G. Benvenuto

We present a grid of evolutionary tracks for low-mass white dwarfs with helium cores in the mass range from 0.179 to 0.414 M_sun. The lower mass limit is well suited for comparison with white dwarf companions of millisecond pulsars (MSP).…

Astrophysics · Physics 2007-05-23 T. Driebe , T. Bloecker , D. Schoenberner

We present a large forward-modeling analysis for 55 late-T (T7-T9) dwarfs, using low-resolution ($R\approx150$) near-infrared spectra and cloudless Sonora-Bobcat model atmospheres. We derive the objects' effective temperatures, surface…

Solar and Stellar Astrophysics · Physics 2021-11-17 Zhoujian Zhang , Michael C. Liu , Mark S. Marley , Michael R. Line , William M. J. Best

We present the results of a new series of non-gray calculations of the atmospheres, spectra, colors, and evolution of extrasolar giant planets (EGPs) and brown dwarfs for effective temperatures below 1300 K. This theory encompasses most of…

White dwarfs represent the endpoint of stellar evolution for stars with initial masses between approximately 0.07 msun and 8-10 msun, where msun is the mass of the Sun (more massive stars end their life as either black holes or neutron…

Astrophysics · Physics 2009-11-13 P. Dufour , James Liebert , G. Fontaine , N. Behara

Kowalski & Saumon (2006) identified the missing absorption mechanism in the observed spectra of cool white dwarf stars as the Ly-alpha red wing formed by the collisions between atomic and molecular hydrogen and successfully explained entire…

Solar and Stellar Astrophysics · Physics 2015-05-20 R. D. Rohrmann , L. G. Althaus , S. O. Kepler

We employed recently computed evolutionary white-dwarf models with helium cores, supplemented by heavier models with carbon-oxygen cores, in order to investigate the ages of millisecond pulsar systems based on the cooling properties of the…

Astrophysics · Physics 2007-05-23 D. Schoenberner , T. Driebe , T. Bloecker

A sequence of pure-hydrogen CO5BOLD 3D model atmospheres of DA white dwarfs is presented for a surface gravity of log g = 8 and effective temperatures from 6000 to 13,000 K. We show that convective properties, such as flow velocities,…

Solar and Stellar Astrophysics · Physics 2015-06-15 P. -E. Tremblay , H. -G. Ludwig , M. Steffen , B. Freytag

We investigate the evolution of isolated, zero and finite temperature, massive, uniformly rotating and highly magnetized white dwarf stars under angular momentum loss driven by magnetic dipole braking. We consider the structure and thermal…

Solar and Stellar Astrophysics · Physics 2019-05-29 Laura Becerra , Kuantay Boshkayev , Jorge. A. Rueda , Remo Ruffini

We present new evolution sequences for very low mass stars, brown dwarfs and giant planets and use them to explore a variety of influences on the evolution of these objects. We compare our results with previous work and discuss the causes…

Astrophysics · Physics 2009-11-13 D. Saumon , M. S. Marley

White dwarfs are the final remnants of low- and intermediate-mass stars. Their evolution is essentially a cooling process that lasts for $\sim 10$ Gyr. Their observed properties provide information about the history of the Galaxy, its dark…

Solar and Stellar Astrophysics · Physics 2016-10-05 Enrique García-Berro , Terry D. Oswalt

We describe the evolution of double degenerate binary systems, consisting of components obeying the zero temperature mass radius relationship for white dwarf stars, from the onset of mass transfer to one of several possible outcomes…

Astrophysics · Physics 2008-11-26 Vayujeet Gokhale , Xiao Meng Peng , Juhan Frank

The characterization of white dwarf atmospheres is crucial for accurately deriving stellar parameters such as effective temperature, mass, and age. We aim to classify the population of white dwarfs up to 500 pc into hydrogen-rich or…

We present seven evolutionary tracks for low-mass white dwarfs with helium cores, ranging in mass from 0.179 to 0.414 Msol. We generated the pre-white dwarf models from a 1 Msol sequence extending up to the tip of its red-giant branch by…

Astrophysics · Physics 2007-05-23 T. Driebe , D. Schoenberner , T. Bloecker , F. Herwig

We investigate the importance of the pseudo-continuum bound-free opacity from hydrogen atoms in the atmospheres of cool white dwarfs. This source of absorption, when calculated by the occupation probability formalism applied in the modeling…

Astrophysics · Physics 2008-11-26 Piotr M. Kowalski

Arguably, the best method for determining the effective temperature ($T_{\mathrm{eff}}$) and surface gravity (log $g$) of a DA white dwarf is by fitting the Hydrogen Lyman and Balmer absorption features. However, as has been shown for white…

Solar and Stellar Astrophysics · Physics 2014-10-06 S. P. Preval , M. A. Barstow , N. R. Badnell , J. B. Holberg , I. Hubeny