J/ApJ/695/1527ivo://CDS.VizieR/J/ApJ/695/1527doi:10.26093/cds/vizier.16951527CDSFekel F.C.Boden A.F.Tomkin J.Torres G.2011-05-27T07:02:25Z2011-05-10T12:17:51ZCDS support team

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

cds-question@unistra.frspectroscopic-binary-starsinterferometryspectroscopyWe have used interferometric and spectroscopic observations of HR 8257 to determine a three-dimensional orbit of the system. The orbit has a period of 12.21345 days and an eccentricity of 0.2895. The masses of the F0 and F2 dwarf components are 1.56 and 1.38M_{sun}_, respectively, with fractional errors of 1.4%. Our orbital parallax of 13.632+/-0.095mas, corresponding to a distance of 73.4+/-0.6pc, differs from the Hipparcos result by just 2% and has a significantly smaller uncertainty. From our spectroscopic observations and spectral energy distribution modeling we determine the component effective temperatures and luminosities to be T_eff_(A)=7030+/-200K and T_eff_(B)=6560+/-200K and L_A_=9.4+/-0.3L_{sun}_ and L_B_=4.7+/-0.2L_{sun}_. The primary rotates pseudosynchronously, while the secondary is not far from its pseudosynchronous rotational velocity. Although both early-F stars are slowly rotating, neither component of this close binary is an Am star. A comparison with evolutionary tracks indicates that the stars are slightly metal poor, and although the components have evolved away from the zero-age main sequence, they are both still dwarfs.2009ApJ...695.1527Fhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/695/1527CatalogResearchIsServedByTAP VizieR generic servicerelated-toV/89 : Ages, Metallicities, Galactic Orbit of F stars (Marsakov+ 1995)B/sb9 : SB9: 9th Catalogue of Spectroscopic Binary Orbits (Pourbaix+V/130 : Geneva-Copenhagen Survey of Solar neighbourhood III (Holmberg+, 2009)J/ApJS/176/276 : PTI calibrator catalog (van Belle+, 2008)J/A+A/450/681 : Companions to close spectroscopic binaries (Tokovinin+, 2006)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/695/1527https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/695/1527http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/695/1527https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/695/1527https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/695/1527http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/695/1527GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/ApJ/695/1527/table2HR 8257 PTI V^2^ data, predictions and residuals from "Joint" orbit modelObsDate of the Observationstime.epochnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMJDModified Julian Date of the Observationdtime.epochdoublelambdaEffective center-band wavelength (1)umem.wlfloatMV2Measured visibility squared (2)instr.calibfloate_MV2Error in MV2instr.calibfloatPV2Predicted visibility squaredinstr.calibfloatResidResidual; data-modelstat.fit.residualfloatuThe u baseline lengthminstr.baselinedoublevThe v baseline lengthminstr.baselinedoublePhaseOrbital phasetime.phasefloat