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      Gaia white dwarfs within 40 pc – I. Spectroscopic observations of new candidates

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          ABSTRACT

          We present a spectroscopic survey of 230 white dwarf candidates within 40 pc of the Sun from the William Herschel Telescope and Gran Telescopio Canarias. All candidates were selected from Gaia Data Release 2 (DR2) and in almost all cases, had no prior spectroscopic classifications. We find a total of 191 confirmed white dwarfs and 39 main-sequence star contaminants. The majority of stellar remnants in the sample are relatively cool (〈Teff〉 = 6200 K), showing either hydrogen Balmer lines or a featureless spectrum, corresponding to 89 DA and 76 DC white dwarfs, respectively. We also recover two DBA white dwarfs and 9–10 magnetic remnants. We find two carbon-bearing DQ stars and 14 new metal-rich white dwarfs. This includes the possible detection of the first ultra-cool white dwarf with metal lines. We describe three DZ stars for which we find at least four different metal species, including one that is strongly Fe- and Ni-rich, indicative of the accretion of a planetesimal with core-Earth composition. We find one extremely massive (1.31 ± 0.01 M⊙) DA white dwarf showing weak Balmer lines, possibly indicating stellar magnetism. Another white dwarf shows strong Balmer line emission but no infrared excess, suggesting a low-mass sub-stellar companion. A high spectroscopic completeness (>99 per cent) has now been reached for Gaia DR2 sources within 40-pc sample, in the Northern hemisphere (δ > 0°) and located on the white dwarf cooling track in the Hertzsprung–Russell diagram. A statistical study of the full northern sample is presented in a companion paper.

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          Gaia Data Release 2

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            The Potential of White Dwarf Cosmochronology

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              A spectroscopic determination of the mass distribution of DA white dwarfs

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                Author and article information

                Contributors
                Journal
                Monthly Notices of the Royal Astronomical Society
                Oxford University Press (OUP)
                0035-8711
                1365-2966
                September 2020
                September 01 2020
                September 2020
                September 01 2020
                July 02 2020
                : 497
                : 1
                : 130-145
                Affiliations
                [1 ]Department of Physics, University of Warwick, Coventry CV4 7AL, UK
                [2 ]European Southern Observatory, Karl Schwarzschild Straße 2, D-85748 Garching, Germany
                [3 ]Instituto de Astrofísica de Canarias, Universidad de La Laguna, E-38205 La Laguna, Tenerife, Spain
                [4 ]Departamento de Astrofísica, Universidad de La Laguna, E-38206 La Laguna, Tenerife, Spain
                [5 ]Institut für Theoretische Physik und Astrophysik, University of Kiel, D-24098 Kiel, Germany
                [6 ]Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138, USA
                [7 ]Institut de Recherche en Astrophysique et Planétologie, CNRS, Université de Toulouse, CNES, 14 Avenue Édouard Belin, F-31400 Toulouse, France
                [8 ]Department of Physics and Astronomy, University College London, London WC1E 6BT, UK
                [9 ]Space Sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège, 19C Allée du Six Août, B-4000 Liège, Belgium
                [10 ]Department of Astronomy, Boston University, 725 Commonwealth Avenue, Boston, MA 02215, USA
                [11 ]Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg, D-69120 Heidelberg, Germany
                [12 ]Instituto de Física da Universidade Federal do Rio Grande do Sul, 91540 Porto Alegre, RS Brazil
                [13 ]Gemini Observatory, 670 N’Aohoku Place, Hilo, HI 96720, USA
                [14 ]INAF-Osservatorio Astronomico di Capodimonte, Salita Moiariello 16, I-80131 Naples, Italy
                [15 ]Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, UK
                [16 ]Institut für Physik und Astronomie, Universität Potsdam, Haus 28, Karl-Liebknecht-Strasse 24/25, D-14476 Potsdam-Golm, Germany
                [17 ]Departament de Física, Universitat Politècnica de Catalunya, c/Esteve Terrades 5, E-08860 Castelldefels, Spain
                [18 ]Institut d’Estudis Espacials de Catalunya, Edifici Nexus-201, c/Gran Capità 2-4, E-08034 Barcelona, Spain
                [19 ]Key Laboratory of Space Astronomy and Technology, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100101, P. R. China
                [20 ]Instituto de Física y Astronomía de la Universidad de Valparaíso, Avenue Gran Bretaña 1111, Valparaíso 2390302, Chile
                [21 ]Millennium Nucleus for Planet Formation, NPF, Universidad de Valparaíso, Valparaíso 2390302, Chile
                [22 ]INAF-Osservatorio Astrofisico di Torino, Strada dell’Osservatorio 20, I-10025 Pino Torinese, Italy
                [23 ]Institute for Gravitational Wave Astronomy, School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, UK
                Article
                10.1093/mnras/staa1892
                ad0aadec-4326-464b-a54d-1d269a9db241
                © 2020

                https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model

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