Model atmosphere analysis of hot WDs from SDSS DR12 J/ApJ/901/93 ivo://CDS.VizieR/J/ApJ/901/93 doi:10.26093/cds/vizier.19010093 CDS Bedard A. Bergeron P. Brassard P. Fontaine G. 2023-06-05T09:52:14Z 2022-02-18T13:14:23Z CDS support team CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France cds-question@unistra.fr white-dwarf-stars visible-astronomy spectroscopy stellar-spectral-types stellar-masses stellar-radii effective-temperature 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 (Teff>=30000K) 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 (75000K>Teff>30000K) 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 (Teff>60000K) white dwarfs. 2020ApJ...901...93B https://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/901/93 Catalog Research IsServedBy TAP VizieR generic service IsServedBy Conesearch service related-to II/207 : Palomar-Green catalog UV-excess stellar objects (Green+ 1986) V/147 : The SDSS Photometric Catalogue, Release 12 (Alam+, 2015) I/345 : Gaia DR2 (Gaia Collaboration, 2018) I/347 : Distances to 1.33 billion stars in Gaia DR2 (Bailer-Jones+, 2018) J/ApJS/133/413 : BVRIJHK photometry of cool white dwarfs (Bergeron+, 2001) J/ApJS/156/47 : DA WDs from the Palomar Green Survey (Liebert+, 2005) J/ApJS/167/40 : SDSS4 confirmed white dwarfs catalog (Eisenstein+, 2006) J/AJ/132/676 : SDSS hot DB white dwarfs (Eisenstein+, 2006) J/ApJ/652/1554 : Iron in hot DA white dwarfs (Vennes+, 2006) J/ApJ/743/138 : Spectroscopic survey of bright WDs (Gianninas+, 2011) J/ApJ/730/128 : Spectroscopy of DA WD from the SDSS-DR4 (Tremblay+, 2011) J/ApJS/204/5 : SDSS DR7 white dwarf catalog (Kleinman+, 2013) J/A+A/555/A96 : White dwarf cooling timescales (Salaris+, 2013) J/A+A/583/A86 : DB white dwarfs in SDSS DR10 and DR12 (Koester+, 2015) J/MNRAS/446/4078 : New white dwarf stars in SDSS DR10 (Kepler+, 2015) J/MNRAS/455/3413 : New WD and subdwarf stars in SDSS DR12 (Kepler+, 2016) J/ApJ/848/11 : Spectroscopic & photometric analysis of WDs (Bedard+, 2017) J/MNRAS/480/1547 : Full Evolutionary Sequences of Massive WDs (Lauffer+, 2018) J/ApJ/878/63 : Cool WD atmosphere models. IV. (Blouin+, 2019) J/ApJ/885/74 : 1340 Helium rich white dwarfs in the Gaia era (Coutu+, 2019) J/ApJ/882/106 : DB WDs with SDSS and Gaia data (Genest-Beaulieu+, 2019) J/A+A/628/A102 : Carbon-rich (DQ) white dwarfs in SDSS (Koester+, 2019) https://cds.unistra.fr/vizier-org/licences_vizier.html https://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/901/93 https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/901/93 http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/901/93 https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/901/93 https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/901/93 http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/901/93 GET text/xml+votable https://tapvizier.cds.unistra.fr/TAPVizieR/tap Cone search capability for table J/ApJ/901/93/table1 (Atmospheric and stellar parameters of hot white dwarfs from SDSS DR12) https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/901/93/table1? https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/901/93/table1? http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/901/93/table1? 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28580 28588 28598 28602 28618 28621 28647 28653-28655 28659 28668 30034 30037 30041-30042 31146 31150 31286 31357 31372 31374 31379 31387 31390 31394 31405 31408 31412 31414 31431 31441 31444 31447 31449 31452 31465 31467 31486 31528 31531 31550 31599 31603 31606 31609 31611 31614 31617-31618 31620 31622 31628-31629 31631 31637-31638 31640 31646-31647 31649 31654 31675-31676 31682 31684 31690 31697-31698 31704 31707 31710 31716 31719 31724-31726 31734 31739 31741 31907-31908 32399 32409 32413 32415 32424-32425 32436 32438 32441 32478 32481-32482 32488 32490 32499 32502 32505-32507 32509 32528 32538 32553 32555 32644 32674 32681 32686 32697-32698 32702 36725-36727 36729 36773 36778 36795 36862-36863 45049 48877 48891 49014-49015 49022 49087 49095 49103 49106-49107 https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/901/93?format=ascii Optical default J/ApJ/901/93/table1 Atmospheric and stellar parameters of hot white dwarfs from SDSS DR12 Rad [0.004/0.072] Radius solRad phys.size.radius float e_Rad [0.0001/0.03] Uncertainty in Rad solRad stat.error float logL [-1.88/3.15] log Luminosity log(solLum) phys.luminosity float e_logL [0.01/1.4] Uncertainty in logL log(solLum) stat.error float l_logtau Limit flag on logtau meta.code.error char recno Record number assigned by the VizieR team. Should Not be used for identification. meta.record int SDSS SDSS identifier (JHHMMSS.ss+DDMMSS.s) meta.id;meta.main char SpT Spectral type src.spType char S/N [2.2/132.5] Signal-to-Noise stat.snr float Teff [30000/150000] Effective temperature K phys.temperature.effective int e_Teff [53/44228] Uncertainty in Teff K stat.error;phys.temperature.effective int log(g) [6.42/9.36] log surface gravity log(cm.s**-2) phys.gravity float e_log(g) [0.01/1.33] Uncertainty in log(g) log(cm.s**-2) stat.error float Atm Atmospheric composition meta.note Mass [0.23/1.32] Mass solMass phys.mass float e_Mass [0.01/0.52] Uncertainty in Mass solMass stat.error;phys.mass float SimbadName Simbad column added by the CDS meta.id char nullable logtau [5.0/8.48] log cooling age log(yr) time.age float e_logtau [0.01/1.8]? Uncertainty in logtau log(yr) stat.error float nullable Note Note codes (1) meta.note char SCat Display data from Kleinman+, 2013, J/ApJS/204/5 ; Kepler+, 2015, J/MNRAS/446/4078 and 2016, J/MNRAS/455/3413 meta.ref.url int nullable Sloan Display the online SDSS-DR12 data for the nearest object meta.ref.url char _RA Positions from SDSS names (right ascension part) deg pos.eq.ra;meta.main _DE Positions from SDSS names (declination part) deg pos.eq.dec;meta.main