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相关论文: The mode trapping properties of full DA white dwar…

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We perform a calibration of the mixing length parameter at the bottom boundary of the convection zone for helium-dominated atmospheres of white dwarfs. This calibration is based on a grid of 3D DB (pure-helium) and DBA (helium-dominated…

太阳与恒星天体物理 · 物理学 2019-09-25 Cukanovaite E. , P. -E. Tremblay , B. Freytag , H. -G. Ludwig , G. Fontaine , P. Brassard , O. Toloza , D. Koester

The ultimate understanding of Type Ia Supernovae diversity is one of the most urgent issues to exploit thermonuclear explosions of accreted White Dwarfs (WDs) as cosmological yardsticks. In particular, we investigate the impact of the…

(Summary of paper) High resolution optical spectroscopy of the white dwarf WD0137-349 reveals a weak Halpha line in emission, due to a low mass companion in a close orbit. Using this emission feature, and the narrow NLTE core of the white…

天体物理学 · 物理学 2009-11-11 P. F. L. Maxted , R. Napiwotzki , P. D. Dobbie , M. R. Burleigh

We describe radial velocity observations of a large sample of apparently single white dwarfs (WDs), obtained in a long-term effort to discover close, double-degenerate (DD) pairs which might comprise viable Type Ia Supernova (SN Ia)…

天体物理学 · 物理学 2009-10-30 Rex A. Saffer , Mario Livio , Lev R. Yungelson

Seismological observations with the Whole Earth Telescope (WET) allow the determination of the subsurface compositional structure of white dwarf stars. The hot DO PG 1159 has a helium surface layer with a mass of 0.001 Msun, while the…

天体物理学 · 物理学 2009-10-08 Benjamin T. Dehner , Steven D. Kawaler

We present a large bank of chemical profiles and pulsation periods suited for asteroseismological studies of ZZ Ceti (or DAV) variable stars. Our background equilibrium DA white dwarf models are the result of fully evolutionary computations…

太阳与恒星天体物理 · 物理学 2012-04-30 Alejandra D. Romero , Alejandro H. Córsico , Leandro G. Althaus , Marcelo M. Miller Bertolami

Hydrogen atmosphere white dwarfs with metal lines, so-called DAZs, show evidence for ongoing accretion of material onto their surfaces. Some DAZs are known to have unresolved M dwarf companions, which could account for the observed…

天体物理学 · 物理学 2011-02-11 J. H. Debes

We consider the combined effects that overshooting and the $^{12}$C($\alpha$, $\gamma$)$^{16}$O reaction rate have on variable white dwarf stellar models. We find that carbon-oxygen white dwarf models continue to yield pulsation signatures…

太阳与恒星天体物理 · 物理学 2023-08-01 Morgan T. Chidester , F. X. Timmes , Ebraheem Farag

We present a new method that investigates the evolutionary history of the pulsating DB white dwarf GD358 using asteroseismology. This is done considering the internal C/O profile, which describes the relative abundances of carbon and oxygen…

天体物理学 · 物理学 2008-02-15 J. M. Gonzalez Perez , T. S. Metcalfe

We construct time-dependent one-dimensional (vertically averaged) models of accretion disks produced by the tidal disruption of a white dwarf (WD) by a binary neutron star (NS) companion. Nuclear reactions in the disk midplane burn the WD…

高能天体物理现象 · 物理学 2016-09-16 Ben Margalit , Brian D. Metzger

Within the theoretical framework of some modern unification theories the constants of nature are functions of cosmological time. White dwarfs offer the possibility of testing a possible variation of G and, thus, to place constraints to…

太阳与恒星天体物理 · 物理学 2015-05-20 L. G. Althaus , A. H. Corsico , S. Torres , P. Loren-Aguilar , J. Isern , E. Garcia-Berro

We present results of a fully non-local model of convection for white dwarf envelopes. We show that this model is able to reproduce the results of numerical simulations for convective efficiencies ranging from very inefficient to moderately…

天体物理学 · 物理学 2016-08-30 M. H. Montgomery , F. Kupka

We present new and improved evolutionary calculations for carbon-oxygen white dwarf (WD) stars appropriate for the study of massive ZZ Ceti stars. We follow the complete evolution of massive WD progenitors from the zero-age main sequence…

天体物理学 · 物理学 2009-11-07 L. G. Althaus , A. M. Serenelli , A. H. Corsico , M. H. Montgomery

We present the scientific case for exploiting the capabilities of the PLATO mission to study bright pulsating white dwarfs across a wide spectral range, including hydrogen-deficient types (GW Vir and DBV stars) and hydrogen-rich classes…

We report the discovery of spectroscopic variations in the magnetic DBA white dwarf SDSS J091016.43+210554.2. Follow-up time-resolved spectroscopy at the Apache Point Observatory (APO) and the MMT show significant variations in the H…

太阳与恒星天体物理 · 物理学 2023-12-12 Adam Moss , P. Bergeron , Mukremin Kilic , Gracyn Jewett , Warren R. Brown , Alekzander Kosakowski , Olivier Vincent

Steadily accreting white dwarfs (WDs) are efficient sources of ionization and thus, are able to create extended ionized nebulae in their vicinity. These nebulae represent ideal tools for the detection of accreting WDs, given that in most…

太阳与恒星天体物理 · 物理学 2022-06-01 D. Souropanis , A. Chiotellis , P. Boumis , M. Chatzikos , S. Akras , L. Piersanti , A. J. Ruiter , G. J. Ferland

We consider envelopes of DB white dwarfs which are not composed of pure 4-He, but rather a mixture of 3-He and 4-He. Given this assumption, the same diffusive processes which produce a relatively pure H layer overlying a He layer in the…

天体物理学 · 物理学 2007-05-23 M. H. Montgomery , T. S. Metcalfe , D. E. Winget

In this paper, we model the observable signatures of tidal disruptions of white dwarf (WD) stars by massive black holes (MBHs) of moderate mass, $\approx 10^3 - 10^5 M_\odot$. When the WD passes deep enough within the MBH's tidal field,…

高能天体物理现象 · 物理学 2017-06-16 Morgan MacLeod , James Guillochon , Enrico Ramirez-Ruiz , Daniel Kasen , Stephan Rosswog

We present the analysis of a total of 177h of high-quality optical time-series photometry of the helium atmosphere pulsating white dwarf (DBV) EC 20058-5234. The bulk of the observations (135h) were obtained during a WET campaign (XCOV15)…

We calculated diffusion timescales for Ca, Mg, Fe in hydrogen atmosphere white dwarfs with temperatures between 5000 and 25000 K. With these timescales we determined accretion rates for a sample of 38 DAZ white dwarfs from the recent…

天体物理学 · 物理学 2009-11-11 D. Koester , D. Wilken
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