J/A+A/453/155ivo://CDS.VizieR/J/A+A/453/155doi:10.26093/cds/vizier.34530155CDSMerand A.Kervella P.Coude du Foresto V.Perrin G.Ridgway S.T.,Aufdenberg J.P.ten Brummelaar T.A.McAlister H.A.Sturmann L.,Sturmann2 J.Turner N.H.Berger D.H.2006-08-12T08:09:29Z2006-08-12T08:06:59ZCDS support team

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

cds-question@unistra.frvariable-starsinterferometryWe present the results of long-baseline interferometric observations of the classical Cepheids Polaris and delta Cep in the near infrared K' band (1.9-2.3 microns), using the FLUOR instrument of the CHARA Array. Following our previous detection of a circumstellar envelope (CSE) around L Car (Kervella et al., 2006A&A...448..623K), we report similar detections around Polaris and delta Cep. Owing to the large data set acquired on Polaris, in both the first and second lobes of visibility function, we have detected the presence of a circum-stellar envelope (CSE), located at 2.4+/-0.1 stellar radii, accounting for 1.5+/-0.4% of the stellar flux in the K' band. A similar model is applied to the delta Cep data, which shows improved agreement compared to a model without CSE. Finally, we find that the bias in estimating the angular diameter of delta Cep in the framework of the Baade-Wesselink method (Merand et al., 2005A&A...438L...9M) is of the order of 1% or less in the K' band. A complete study of the influence of the CSE is proposed in this context, showing that at the optimum baseline for angular diameter variation detection, the bias is of the order of the formal precision in the determination of the delta Cep pulsation amplitude (1.6%). Description: Individual interferometric squared visibility measurements. Data were acquired in the wide infrared K' band. We also provide informations about calibrator stars.2006A&A...453..155Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/453/155CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/A+A/428/587 : Cepheids BVRIJHK dereddened magnitudes (Kervella+, 2004)J/A+A/281/465 : Chemical Composition of alf UMi and V473 Lyr (Andrievsky+ 1994)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/453/155https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/453/155http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/453/155https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/453/155https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/453/155http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/453/155GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/A+A/453/155/table4Individuals interferometric V2 measurementsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHRHR number (424 for Polaris, 8571 for delta Cep)meta.id;meta.mainintjd-jd0Julian date - jd0 (1)dtime.epochdoublephasepulsating phasetime.phasefloatubaseline projection toward Eastminstr.baselinefloatvbaseline projection toward Northminstr.baselinefloatV2Wide band squared visibility in 1/100%instr.calibfloate_V2Absolute error in V2%stat.errorfloatHDaHD of calibrator star A, (0 means no cal. A)meta.idintalphaCorrelated errors matrix coef. (2)stat.correlationfloate_V2aAbsolute error in V2 for cal. A (2)%stat.errorfloatHDbHD of calibrator star B, (0 means no cal. B)meta.idintbetaCorrelated errors matrix coef. (2)stat.correlationfloate_V2bAbsolute error in V2 for cal. B (2)%stat.errorfloat