J/A+A/635/A33ivo://CDS.VizieR/J/A+A/635/A33doi:10.26093/cds/vizier.36350033CDSGroenewegen M.A.T2021-01-05T12:50:32Z2020-03-02T08:17:20ZCDS support team

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

cds-question@unistra.frvariable-starsstellar-distancevisible-astronomytrigonometric-parallaxSpectral energy distributions (SEDs) were constructed for a sample of 477 classical cepheids (CCs); including stars that have been classified in the literature as such but are probably not. The SEDs were fitted with a dust radiative transfer code. Four stars showed a large mid- or far-infrared excess and the fitting then included a dust component. These comprise the well-known case of RS Pup, and three stars that are (likely) Type-II cepheids (T2Cs), AU Peg, QQ Per, and FQ Lac. The infrared (IR) excess in FQ Lac is reported for the first time in this work. The remainder of the sample was fitted with a stellar photosphere to derive the best-fitting luminosity and effective temperature. Distance and reddening were taken from the literature. The stars were plotted in a Hertzsprung-Russell diagram (HRD) and compared to evolutionary tracks for cepheids and theoretical instability strips. For the large majority of stars, the position in the HRD is consistent with the instability strip for a CC or T2C. About 5% of the stars are outliers in the sense that they are much hotter or cooler than expected. A comparison to effective temperatures derived from spectroscopy suggests in some cases that the photometrically derived temperature is not correct and that this is likely linked to an incorrectly adopted reddening. Two three-dimensional reddening models have been used to derive alternative estimates of the reddening for the sample. There are significant systematic differences between the two estimates with a non-negligible scatter. In this work the presence of a small near-infrared (NIR) excess, as has been proposed in the literature for a few well-known cepheids, is investigated. Firstly, this was done by using a sample of about a dozen stars for which a mid-infrared spectrum is available. This data is particularly con straining as the shape of the observed spectrum should match that of the photosphere and any dust spectrum, both dust continuum and any spectral features of, for example, silicates or aluminium oxide. This comparison provides constraints on the dust composition, in agreement with a previous work in the literature. Secondly, the SEDs of all stars were fitted with a dust model to see if a statistically significant better fit could be obtained. The results were compared to recent work. Eight new candidates for exhibiting a NIR excess are proposed, solely based on the photometric SEDs. Obtaining mid-infrared spectra would be needed to confirm this excess. Finally, period-bolometric luminosity and period-radius relations are presented for samples of over 370 fundamental-mode CCs.2020A&A...635A..33Ghttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/635/A33CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/635/A33https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/635/A33http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/635/A33https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/635/A33https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/635/A33http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/635/A33GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/A+A/635/A33/table1starsSimbadNameSimbad column added by the CDSmeta.idcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameThe variable star namemeta.id;meta.maincharprimaryType1The classification of the variabilitymeta.code.class;src.varcharType2An alternative classification of the variability (1)meta.code.class;src.varcharPeriod? The pulsation perioddtime.periodfloatnullableE(B-V)The reddeningmagphot.color.excessfloatmoreindicates more reddening values in tablea1meta.ref.urlchare_E(B-V)The reddening errormagstat.errorfloatdistThe distance (2)kpcpos.distancefloatr_distReference (2)meta.ref;pos.frameinte_distThe error in the distancekpcstat.errorfloatdist2? An alternative distance with error bars (3)kpcpos.distancefloatnullableE_dist2? An alternative distance with error bars (3)kpcstat.error;stat.maxfloatnullablee_dist2? An alternative distance with error bars (3)kpcstat.errorfloatnullableLumThe stellar luminosity with error barsolLumphys.luminositydoublee_LumThe stellar luminosity with error barsolLumstat.errorfloatTeffThe effective temperatureKphys.temperature.effectiveinte_TeffThe effective temperatureKstat.error;phys.temperature.effectiveintthetaThe predicted angular diametermasphys.angSizefloate_thetaThe predicted angular diametermasstat.error;pos.posAngfloatRemarksAngular diameters from the literaturemeta.notecharJ/A+A/635/A33/tablea1Different reddening valuesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameThe variable star namemeta.id;meta.maincharE(B-V)1The adopted reddening (1)magphot.color.excessfloate_E(B-V)1The error in the adopted reddening (1)magstat.errorfloatE(B-V)2? An alternative reddening (2)magphot.color.excessfloatnullablee_E(B-V)2? The error in the reddening E(B-V)2 (2)magstat.errorfloatnullableE(B-V)3aAn alternative reddening (3)magphot.color.excessfloatE(B-V)3bAn alternative reddening (3)magphot.color.excessfloate_E(B-V)3aThe error in the reddening E(B-V)3a and E(B-V)3b (3)magstat.errorfloatE(B-V)4? An alternative reddening (4)magphot.color.excessfloatnullablee_E(B-V)4? The error in the reddening E(B-V)4 (4)magstat.errorfloatnullableRemarksRemarks (5)meta.notecharJ/A+A/635/A33/referReferences for angular diametersComCommentsmeta.notecharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRefReference codemeta.notechar