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Observational tests of stellar and Galactic chemical evolution call for the joint knowledge of a star's physical parameters, detailed element abundances, and precise age. For cool main-sequence (MS) stars the abundances of many elements can…

太阳与恒星天体物理 · 物理学 2019-01-09 M. Fouesneau , H. -W. Rix , T. von Hippel , D. W. Hogg , H. Tian

Only a handful of gas giant planets orbiting white dwarfs are known. It remains unclear whether this paucity reflects observational challenges or the consequences of stellar evolution. We aim to carry out population synthesis of substellar…

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…

天体物理学 · 物理学 2011-02-11 Brad M. S. Hansen

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…

太阳与恒星天体物理 · 物理学 2024-09-13 Sivan Ginzburg

A detailed analysis of 32 of the 38 halo white dwarf candidates identified by Oppenheimer et al. is presented, based on model atmosphere fits to observed energy distributions built from optical BVRI and infrared JHK CCD photometry.…

天体物理学 · 物理学 2009-11-10 P. Bergeron , Maria Teresa Ruiz , M. Hamuy , S. K. Leggett , M. J. Currie , C. -P. Lajoie , P. Dufour

The determination of atmospheric parameters of white dwarf stars (WDs) is crucial for researches on them. Traditional methodology is to fit the model spectra to observed absorption lines and report the parameters with the lowest $\chi ^2$…

天体物理仪器与方法 · 物理学 2021-11-29 Yong Yang , Jingkun Zhao , Jiajun Zhang , Xianhao Ye , Gang Zhao

WASP-98 is a planetary system containing a hot Jupiter transiting a late-G dwarf. A fainter star 12 arcsec distant has previously been identified as a white dwarf, with a distance and proper motion consistent with a physical association…

太阳与恒星天体物理 · 物理学 2020-08-19 John Southworth , P. -E. Tremblay , B. T. Gaensicke , D. F. Evans , T. Mocnik

Cool white dwarfs are reliable and independent stellar chronometers. The most common white dwarfs have carbon-oxygen dense cores. Consequently, the cooling ages of very cool white dwarfs sensitively depend on the adopted phase diagram of…

太阳与恒星天体物理 · 物理学 2015-05-30 Leandro G. Althaus , Enrique García-Berro , Jordi Isern , Alejandro H. Córsico , Marcelo M. Miller Bertolami

With the state-of-the-art Gaia astrometry, the number of confirmed white dwarfs has reached a few hundred thousand. We have reached the era where small features in the white dwarf luminosity function (WDLF) of the solar neighbourhood can be…

太阳与恒星天体物理 · 物理学 2026-01-21 Marco C Lam , Nicholas Rowell

We present evolutionary calculations and colors for massive white dwarfs with oxygen-neon cores for masses between 1.06 and 1.28 Mo. The evolutionary stages computed cover the luminosity range from log(L/Lo) approx. 0.5 down to -5.2. Our…

天体物理学 · 物理学 2016-08-14 L. G. Althaus , E. García-Berro , J. Isern , A. H. Córsico , R. D. Rohrmann

We present the mass distribution for all S/N > 15 pure DA white dwarfs detected in the Sloan Digital Sky Survey up to Data Release 12, fitted with Koester models for ML2/alpha=0.8, and with Teff > 10 000 K, and for DBs with S/N >10, fitted…

太阳与恒星天体物理 · 物理学 2016-10-04 S. O. Kepler , Detlev Koester , Alejandra Daniela Romero , Gustavo Ourique , Ingrid Pelisoli

We use the most recent, complete and independent measurements of masses and radii of white dwarfs in binaries to bound the class of non-trivial modified gravity theories, viable after GW170817/GRB170817, using its effect on the mass-radius…

宇宙学与河外天体物理 · 物理学 2018-05-23 Ippocratis D. Saltas , Ignacy Sawicki , Ilidio Lopes

Ultra-cool white dwarfs are among the oldest stellar remnants in the Universe. Their efficient gravitational settling and low effective temperatures are responsible for the smooth spectra they exhibit. For that reason, it is not possible to…

太阳与恒星天体物理 · 物理学 2020-04-08 M. C. Lam , N. C. Hambly , N. Lodieu , S. Blouin , E. J. Harvey , R. J. Smith , M. C. Galvez-Ortiz , Z. H. Zhang

We present a catalogue of white dwarf candidates selected from Gaia early data release three (EDR3). We applied several selection criteria in absolute magnitude, colour, and Gaia quality flags to remove objects with unreliable measurements…

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…

天体物理仪器与方法 · 物理学 2015-06-12 Luis M. Sarro , Angel Berihuete , Cesar Carrion , David Barrado , Patricia Cruz , Yago Isasi

Using WFPC2 on the Hubble Space Telescope, we have isolated a sample of 258 white dwarfs (WDs) in the Galactic globular cluster M4. Fields at three radial distances from the cluster center were observed and sizeable WD populations were…

The $Gaia$ mission has provided an unprecedented wealth of information about the white dwarf population of our Galaxy. In particular, our studies show that the sample up to 100\,pc from the Sun can be considered as practically complete.…

太阳与恒星天体物理 · 物理学 2022-02-23 S. Torres , P. Canals , F. M. Jiménez-Esteban , A. Rebassa-Mansergas , E. Solano

The observational signature of core crystallization of white dwarfs has recently been discovered. However, the magnitude of the crystallization-powered cooling delay required to match observed white dwarfs is larger than predicted by…

太阳与恒星天体物理 · 物理学 2023-06-30 Alexander Venner , Simon Blouin , Antoine Bédard , Andrew Vanderburg

We calculate the expected white dwarf luminosity functions and discovery functions in photometric passbands, if these stellar remnants provide a substantial fraction of the sought Galactic dark matter, as suggested on various observational…

天体物理学 · 物理学 2009-10-31 Gilles Chabrier

We present a detailed analysis of the white dwarf luminosity functions derived from the local 40 pc sample and the deep proper motion catalog of Munn et al (2014, 2017). Many of the previous studies ignored the contribution of thick disk…