Evidence of spectral evolution on the white dwarf sample from the <i>Gaia</i> mission

Ourique, Gustavo; Romero, A. D.; Klippel, Theylor Schumacher; Koester, D.

doi:10.1093/mnras/staa120

Cited by 13 publications

(11 citation statements)

References 58 publications

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“…Analyzing the particular details of our distribution, we discern some of the characteristics already presented in previous works. For instance, in the range of temperatures between ∼ 23 000 and ∼ 13 000 K, our spectral distribution is nearly constant with an average ratio of ∼ 13% and a slight growth up to 13 000 K. This behaviour is compatible with most of the distributions: Ourique et al (2020), López-Sanjuan et al (2022, Cunningham et al (2020), and. At that point, there is an abrupt increase that reaches its maximum fraction, 𝑓 36% at 𝑇 eff ∼ 10 500 K, which corresponds to the bifurcation zone in the Gaia HR diagram.…”

Section: The Ratio Of Da To Non-da White Dwarfssupporting

confidence: 74%

“…Several alternative explanations to avoid this problem have been proposed, such as mixed hydrogenhelium atmospheres, or spectral evolution from hydrogen to helium envelopes, among others (e.g. Bergeron et al 2019;Ourique et al 2020). In any case, the characterization of the A and B branches has been limited to the spectroscopically identified white dwarfs in that region, leading to a large fraction of unidentified objects and, consequently, to ignore the real fraction of DA and non-DA in these branches.…”

Section: The Hertzsprung-russell Diagram For Da and Non-da White Dwarfsmentioning

confidence: 99%

“…The ratio of DA to non-DA white dwarfs as a function of the effective temperature, also commonly referred to as the spectral evolution, is a capital tool for understanding the evolutionary processes in white dwarf atmospheres (e.g. Ourique et al 2020;Cunningham et al 2020, and references therein). Due to the diversity of selection effects, one of the major problems that previous studies had to face when building a detailed spectral evolution function was the incompleteness of the analyzed samples.…”

Section: The Ratio Of Da To Non-da White Dwarfsmentioning

confidence: 99%

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Spectral classification of the 100 pc white dwarf population from Gaia-DR3 and the Virtual Observatory

Jiménez-Esteban,

Torres,

Rebassa-Mansergas

et al. 2022

Preprint

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The third data release of Gaia has provided low resolution spectra for ∼ 100 000 white dwarfs (WDs) that, together with the excellent photometry and astrometry, represent an unrivalled benchmark for the study of this population. In this work, we first built a highly-complete volume-limited sample consisting in 12 718 WDs within 100 pc from the Sun. The use of VOSA tool allowed us to perform an automated fitting of their spectral energy distributions to different atmospheric models. In particular, the use of spectrally derived J-PAS photometry from Gaia spectra led to the classification of DA and non-DA WDs with an accuracy > 90%, tested in already spectroscopically labelled objects. The excellent performance achieved was extended to practically the whole population of WDs with effective temperatures above 5500 K. Our results show that, while the A branch of the Gaia WD Hertzsprung-Russell diagram is practically populated by DA WDs, the B branch is largely formed by non-DAs (65%). The remaining 35% of DAs within the B branch implies a second peak at ∼ 0.8 M in the DAmass distribution. Additionally, the Q branch and its extension to lower temperatures can be observed for both DA and non-DA objects due to core crystallisation. Finally, we derived a detailed spectral evolution function, which confirms a slow increase of the fraction of non-DAs as the effective temperature decreases down to 10 500 K, where it reaches a maximum of 36% and then decreases for lower temperatures down to ∼ 31%.

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Section: The Ratio Of Da To Non-da White Dwarfssupporting

confidence: 74%

Section: The Hertzsprung-russell Diagram For Da and Non-da White Dwarfsmentioning

confidence: 99%

Section: The Ratio Of Da To Non-da White Dwarfsmentioning

confidence: 99%

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Spectral classification of the 100 pc white dwarf population from Gaia-DR3 and the Virtual Observatory

Jiménez-Esteban,

Torres,

Rebassa-Mansergas

et al. 2022

Preprint

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“…This model grid is an e xtended v ersion of the model grid presented in Romero et al ( 2019b ) that includes new cooling sequences with stellar masses between 0.5 and 1.0 M , along with approximately eight hydrogen layer values for each sequence, depending on the stellar mass. For hydrogen envelopes thinner than 10 −10 M * the outer conv ectiv e zone will mix the hydrogen into the more massive helium layer before reaching the ZZ Ceti instability strip, turning the star into a DB white dwarf (Cunningham et al 2020 ;Ourique et al 2020 ). For each model in our grid, we computed non-radial g-mode pulsations, considering the adiabatic approximation, using the adiabatic version of the LP-PUL pulsation code (see C órsico & Althaus 2006 , for details).…”

Section: A S T E Ro S E I S M O L O G I C a L A Na Ly S I Smentioning

confidence: 99%

Discovery of 74 new bright ZZ Ceti stars in the first three years of TESS

Romero

Hermes

Amaral

et al. 2022

Monthly Notices of the Royal Astronomical Society

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We report the discovery of 74 new pulsating DA white dwarf stars, or ZZ Cetis, from the data obtained by the Transiting Exoplanet Survey Satellite (TESS) mission, from Sectors 1 to 39, corresponding to the first 3 cycles. This includes objects from the Southern Hemisphere (Sectors 1–13 and 27–39) and the Northern Hemisphere (Sectors 14–26), observed with 120 s- and 20 s-cadence. Our sample likely includes 13 low-mass and one extremely low-mass white dwarf candidate, considering the mass determinations from fitting Gaia magnitudes and parallax. In addition, we present follow-up time series photometry from ground-based telescopes for 11 objects, which allowed us to detect a larger number of periods. For each object, we analysed the period spectra and performed an asteroseismological analysis, and we estimate the structure parameters of the sample, i.e. stellar mass, effective temperature and hydrogen envelope mass. We estimate a mean asteroseismological mass of 〈Msis〉= 0.635± 0.015 M⊙, excluding the candidate low or extremely-low mass objects. This value is in agreement with the mean mass using estimates from Gaia data, which is 〈Mphot〉= 0.631± 0.040 M⊙, and with the mean mass of previously known ZZ Cetis of 〈M*〉= 0.644 ± 0.034 M⊙. Our sample of 74 new bright ZZ Cetis increases the number of known ZZ Cetis by ∼20 per cent.

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“…We now review the progress that has been made over the years toward the achievement of this goal. Since it would be impossible to cover the whole subject in detail, in the present paper we restrict our attention to the early phases of degenerate evolution, more specifically to hot white dwarfs with effective temperatures T eff ≥ 30, 000 K. The reader is referred to Rolland et al (2018Rolland et al ( , 2020, Ourique et al (2019Ourique et al ( , 2020, Blouin et al (2019), Genest-Beaulieu & Bergeron (2019a, Coutu et al (2019), and Cunningham et al (2020) for recent studies of the spectral evolution of cooler remnants.…”

Section: Introductionmentioning

confidence: 99%

On the Spectral Evolution of Hot White Dwarf Stars. I. A Detailed Model-Atmosphere Analysis of Hot White Dwarfs from SDSS DR12

Bédard,

Bergeron,

Brassard

et al. 2020

Preprint

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As they evolve, white dwarfs undergo major changes in surface composition, a phenomenon known as spectral evolution. In particular, some stars enter the cooling sequence with helium atmospheres (type DO) but eventually develop hydrogen atmospheres (type DA), most likely through the upward diffusion of residual hydrogen. Our empirical knowledge of this process remains scarce: the fractions of white dwarfs that are born helium-rich and that experience the DO-to-DA transformation are poorly constrained. We tackle this issue by performing a detailed model-atmosphere investigation of 1806 hot (T eff ≥ 30, 000 K) white dwarfs observed spectroscopically by the Sloan Digital Sky Survey. We first introduce our new generations of model atmospheres and theoretical cooling tracks, both appropriate for hot white dwarfs. We then present our spectroscopic analysis, from which we determine the atmospheric and stellar parameters of our sample objects. We find that ∼24% of white dwarfs begin their degenerate life as DO stars, among which ∼2/3 later become DA stars. We also infer that the DO-to-DA transition occurs at substantially different temperatures (75, 000 K > T eff > 30, 000 K) for different objects, implying a broad range of hydrogen content within the DO population. Furthermore, we identify 127 hybrid white dwarfs, including 31 showing evidence of chemical stratification, and we discuss how these stars fit in our understanding of the spectral evolution. Finally, we uncover significant problems in the spectroscopic mass scale of very hot (T eff > 60, 000 K) white dwarfs.

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Evidence of spectral evolution on the white dwarf sample from the Gaia mission

Cited by 13 publications

References 58 publications

Spectral classification of the 100 pc white dwarf population from Gaia-DR3 and the Virtual Observatory

Spectral classification of the 100 pc white dwarf population from Gaia-DR3 and the Virtual Observatory

Discovery of 74 new bright ZZ Ceti stars in the first three years of TESS

On the Spectral Evolution of Hot White Dwarf Stars. I. A Detailed Model-Atmosphere Analysis of Hot White Dwarfs from SDSS DR12

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