J/A+A/363/1040ivo://CDS.VizieR/J/A+A/363/1040doi:10.26093/cds/vizier.33631040CDSFriedrich S.Koester D.Christlieb N.Reimers D.Wisotzki L.2012-09-24T09:04:40Z2000-12-09T10:07:08ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frwhite-dwarf-starsspectroscopyeffective-temperatureWe present an analysis of 40 cool helium-rich white dwarfs found in the Hamburg/ESO survey. They were selected for follow-up spectroscopy because of their U-B colour below -0.18, the absence of strong absorption lines, and a continuum shape similar to that of a quasar. Effective temperatures for individual stars were determined by fitting model atmospheres of nearly pure helium with a small admixture of hydrogen. As a consequence of the selection criteria all but one sample stars have T_eff_ below 20000K. Four stars clearly show helium and hydrogen lines in their spectra. In the spectra of another three, helium, hydrogen, and metal lines can be detected. For these stars hydrogen and metal abundances were also determined by fitting appropriate model atmospheres containing these elements. Seven sample stars most likely have helium-rich atmospheres but do not show any helium lines. They either have featureless spectra or show calcium lines.2000A&A...363.1040Fhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/363/1040CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toIII/210 : Spectroscopically Identified White Dwarfs (McCook+, 1999)J/A+AS/115/235 : The Hamburg/ESO survey for bright QSOs. II. (Reimers+, 1996)J/A+A/358/77 : Hamburg/ESO survey for bright QSOs. III. (Wisotzki+, 2000)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/363/1040https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/363/1040http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/363/1040https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/363/1040https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/363/1040http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/363/1040GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/363/1040/table2 (Coordinates, magnitudes, cross-references and spectral types, if already existing, for the observed objects.)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/363/1040/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/363/1040/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/363/1040/table2?GETtext/xml+votable180.050000true1.65-14.6038890.0055555555555555566/16665 17177 18602 18649 24886 24996 25236 25244 25297 25302 25389 25640 26010 26762 26958 26960 26975 33533 33956 34185 34446 34662 34686 34693 35086 35647 35711 35727 35738 35832 36257 36639 40293 44649 44732 44738 44936 44972 46867https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/363/1040?format=asciiOpticaldefaultJ/A+A/363/1040/table2Coordinates, magnitudes, cross-references and spectral types, if already existing, for the observed objects.ExpTimeExposure timestime.duration;obs.exposureintrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHESHES name (Hamburg/ESO Survey)meta.id;meta.maincharprimaryNameOther name of object (1)meta.idcharn_Name[2/4]? Notes on other names (2)meta.noteintnullableSpTypeSpectral typesrc.spTypecharn_SpType[1]? Note on SpType (3)meta.noteintnullableFieldNumber of ESO/SERC atlas fieldmeta.id;obs.fieldintRA2000Right ascension (2000)pos.eq.ra;meta.mainDE2000Declination (2000)pos.eq.dec;meta.mainBJmagB_J_ magnitudemagphot.mag;em.opt.BfloatCampaignYear, month and telescope of the first observationmeta.id;obscharCampaign2Year, month and telescope of the second observationmeta.id;obscharExpTime2? Exposure time for campaign 2stime.duration;obs.exposureintnullableCampaign3Year, month and telescope of the third observationmeta.id;obscharExpTime3? Exposure time for campaign 3stime.duration;obs.exposureintnullable_RA.icrsRight ascension (ICRS) (computed by VizieR, not part of the original data)pos.eq.ranullableindexed_DE.icrsDeclination (ICRS) (computed by VizieR, not part of the original data)pos.eq.decnullableindexedJ/A+A/363/1040/spectraList of data files for spectrumrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHESHES name (Hamburg/ESO Survey)meta.id;meta.maincharprimaryFileAssociated spectrum file name in "fig" subdirectorymeta.id;meta.filecharJ/A+A/363/1040/table3aResults from the temperature and logg determination and derived spectral types for the analyzed stars.recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHESHES name (Hamburg/ESO Survey)meta.id;meta.maincharTypeDerived spectral typesrc.spTypecharTeffDerived effective TemperatureKphys.temperature.effectiveinte_Teffrms uncertainty on TeffKstat.error;phys.temperature.effectiveintloggDerived log glog(cm.s**-2)arith.zpfloate_loggrms uncertainty on logglog(cm.s**-2)stat.errorfloatTeff8Derived effective temperature for logg=8 (fixed)Kphys.temperature.effectiveinte_Teff8rms uncertainty on Teff8Kstat.errorintRemEquivalent widths (in {AA}) of spectral lines and remarks on individual starsmeta.notechar