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Axions are the natural consequence of the introduction of the Peccei-Quinn symmetry to solve the strong CP problem. All the efforts to detect such elusive particles have failed up to now. Nevertheless, it has been recently shown that the…

Solar and Stellar Astrophysics · Physics 2015-05-18 J. Isern , E. García-Berro , L. G. Althaus , A. H. Córsico

White dwarf (WD) stars evolve simply and predictably, making them reliable age indicators. However, self-consistent validation of the methods for determining WD total ages has yet to be widely performed. This work uses 1565 wide ( > 100 au)…

Solar and Stellar Astrophysics · Physics 2022-08-17 Tyler M. Heintz , J. J. Hermes , Kareem El-Badry , Charlie Walsh , Jennifer L. van Saders , C. E. Fields , Detlev Koester

About 10% of all stars exhibit absorption lines of ultra-high excited (UHE) metals (e.g. OVIII) in their optical spectra when entering the white dwarf cooling sequence. The recent discovery of a both spectroscopic and photometric variable…

Solar and Stellar Astrophysics · Physics 2021-04-07 Nicole Reindl , Veronika Schaffenroth , Semih Filiz , Stephan Geier , Ingrid Pelisoli , S. O. Kepler

Ultra-massive hydrogen-rich (DA spectral type) white dwarf (WD) stars ($M_{\star} > 1M_{\odot}$) coming from single-star evolution are expected to harbor cores made of $^{16}$O and $^{20}$Ne, resulting from semi-degenerate carbon burning…

Solar and Stellar Astrophysics · Physics 2020-11-24 A. H. Córsico , F. C. De Gerónimo , M. E. Camisassa , L. G. Althaus

Given the importance of white dwarfs (WDs) in many fields of modern astrophysics, the precise knowledge of the actual degree of accuracy of the associated theoretical predictions is a primary task. In the first paper of a series dedicated…

Astrophysics · Physics 2009-11-13 P. G. Prada Moroni , O. Straniero

Sufficiently old white dwarfs cool down through a convective envelope that directly couples their degenerate cores to the surface. Magnetic fields may inhibit this convection by stiffening the criterion for convective instability. We…

Solar and Stellar Astrophysics · Physics 2024-09-13 Sivan Ginzburg

We provide a fine and homogeneous grid of evolutionary sequences for He-core white dwarfs with masses 0.15-0.45 Msun, including the mass range for ELM white dwarfs (<0.20Msun). The grid is appropriate for mass and age determination, and to…

Solar and Stellar Astrophysics · Physics 2015-06-16 Leandro G. Althaus , Marcelo M. Miller Bertolami , Alejandro H. Córsico

The spectral distribution of field white dwarfs shows a feature called the "non-DA gap". As defined by Bergeron et al., this is a temperature range (5100K--6100K) where relatively few non-DA stars are found, even though such stars are…

Solar and Stellar Astrophysics · Physics 2015-06-05 Eugene Y. Chen , Brad M. S. Hansen

We present a new model for the Galactic population of close double white dwarfs. The model accounts for the suggestion of the avoidance of a substantial spiral-in during mass transfer between a giant and a main-sequence star of comparable…

Astrophysics · Physics 2015-05-20 Lev Yungelson , Gijs Nelemans , Simon. F. Portegies Zwart , Frank Verbunt

Pulsating white dwarf stars can be used as astrophysical laboratories to constrain the properties of weakly interacting particles. Comparing the cooling rates of these stars with the expected values from theoretical models allows us to…

Solar and Stellar Astrophysics · Physics 2015-06-22 Alejandro H. Córsico , Leandro G. Althaus , Marcelo M. Miller Bertolami , S. O. Kepler , Enrique García-Berro

We aimed to assess the accuracy of the Gaia teff and logg estimates as derived with current models and observations. We assessed the validity of several inference techniques for deriving the physical parameters of ultra-cool dwarf stars. We…

Instrumentation and Methods for Astrophysics · Physics 2015-06-12 Luis M. Sarro , Angel Berihuete , Cesar Carrion , David Barrado , Patricia Cruz , Yago Isasi

White dwarf evolution is essentially a gravothermal cooling process, which,for cool white dwarfs, sensitively depends on the treatment of the outer boundary conditions. We provide detailed outer boundary conditions appropriate for computing…

Solar and Stellar Astrophysics · Physics 2015-06-11 R. D. Rohrmann , L. G. Althaus , E. García-Berro , A. H. Córsico , M. M. Miller Bertolami

White dwarf stars constitute the final evolutionary stage for more than 95 per cent of all stars. The Galactic population of white dwarfs conveys a wealth of information about several fundamental issues and are of vital importance to study…

Solar and Stellar Astrophysics · Physics 2019-09-11 Alejandro H. Córsico , Leandro G. Althaus , Marcelo M. Miller Bertolami , S. O. Kepler

We respond to the paper by De Marchi, Paresce, Straniero and Moroni (2003) on the white dwarf cooling age of M4. The authors question the data analysis and interpretation that led to the conclusions in Hansen et al. (2002). In their paper,…

We present follow-up spectroscopy of 711 white dwarfs within 100 pc, and present a detailed model atmosphere analysis of the 100 pc white dwarf sample in the SDSS footprint. Our spectroscopic follow-up is complete for 83% of the white…

Solar and Stellar Astrophysics · Physics 2020-08-05 Mukremin Kilic , P. Bergeron , Alekzander Kosakowski , Warren R. Brown , Marcel A. Agueros , Simon Blouin

We study the consequences of superconducting quark cores (with color-flavor-locked phase as representative example) for evolution of temperature profiles and the cooling curves in quark-hadron hybrid stars and in hypothetical self-bounded…

Astrophysics · Physics 2009-10-31 D. Blaschke , H. Grigorian , D. N. Voskresensky

We show that within a recently developed nonlocal, chiral quark model the critical densities for a phase transition to color superconducting quark matter under neutron star conditions can be low enough that these phases occur in compact…

Astrophysics · Physics 2017-08-23 D. Blaschke , D. N. Voskresensky , H. Grigorian

We present the first radiation magnetohydrodynamics simulations of the atmosphere of white dwarf stars. We demonstrate that convective energy transfer is seriously impeded by magnetic fields when the plasma-beta parameter, the thermal to…

Solar and Stellar Astrophysics · Physics 2015-10-14 P. -E. Tremblay , G. Fontaine , B. Freytag , O. Steiner , H. -G. Ludwig , M. Steffen , S. Wedemeyer , P. Brassard

47 Tucanae is one of the most interesting and well observed and theoretically studied globular clusters. This allows us to study the reliability of our understanding of white dwarf cooling sequences, to confront different methods to…

Astrophysics of Galaxies · Physics 2015-06-23 Enrique García-Berro , Santiago Torres , Leandro G. Althaus , Marcelo M. Miller Bertolami

We have exploited Gaia Data Release 2 to study white dwarf members of the Praesepe star cluster. We recovered eleven known white dwarf members (all DA spectral type) plus a new cluster WD never identified before. Two of the eleven known DA…

Astrophysics of Galaxies · Physics 2018-12-12 M. Salaris , L. R. Bedin , .