J/AJ/152/2ivo://CDS.VizieR/J/AJ/152/2doi:10.26093/cds/vizier.51520002CDSLacy C.H.S.Fekel F.C.Pavlovski K.Torres G.Muterspaugh M.W.2017-07-11T13:09:00Z2016-09-12T13:32:05ZCDS support team

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

cds-question@unistra.freclipsing-binary-starsradial-velocityphotometryNP Per is a well-detached, 2.2 day eclipsing binary whose components are both pre-main-sequence stars that are still contracting toward the main-sequence phase of evolution. We report extensive photometric and spectroscopic observations with which we have determined their properties accurately. Their surface temperatures are quite different: 6420+/-90K for the larger F5 primary star and 4540+/-160K for the smaller K5e star. Their masses and radii are 1.3207+/-0.0087 solar masses and 1.372+/-0.013 solar radii for the primary, and 1.0456+/-0.0046 solar masses and 1.229+/-0.013 solar radii for the secondary. The orbital period is variable over long periods of time. A comparison of the observations with current stellar evolution models from MESA indicates that the stars cannot be fit at a single age: the secondary appears significantly younger than the primary. If the stars are assumed to be coeval and to have the age of the primary (17Myr), then the secondary is larger and cooler than predicted by current models. The H{alpha} spectral line of the secondary component is completely filled by, presumably, chromospheric emission due to a magnetic activity cycle.2016AJ....152....2Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/152/2CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/AJ/147/148 : Spectroscopy and photometry of AP And (Lacy+, 2014)J/AJ/142/185 : Properties of the eclipsing binary stars HY Vir (Lacy+, 2011)J/AJ/130/2838 : Velocity and light curves of RW Lac (Lacy+, 2005)J/A+A/384/145 : Compiled catalog of Per OB2 star forming complexhttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/152/2https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/152/2http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/152/2https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/152/2https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/152/2http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/152/2GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/AJ/152/2/table8Observed dates of minimum light for NP PerrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintType[1/2] Eclipse type (1=deep, or 2=shallow eclipse)meta.codeintHJD[18275/56956] Heliocentric Julian Date (HJD-2400000)dtime.epochdoublee_HJD[0.0001/0.03] Uncertainty in HJD of eclipse datedstat.error;time.epochfloatO-C[-0.34/0.014] Eclipse O-C residualdstat.fit.residual;stat.fit.omcdoubleRef[1/18] Reference (1)meta.ref;pos.frameintJ/AJ/152/2/table1Heliocentric radial velocities for NP PerrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHJD[55888/56978] Heliocentric Julian Date (HJD-2400000)dtime.epochdoublePhase[0/1] Phase in the inner orbittime.phasefloatHRVA[-77.4/113.5] Star A heliocentric radial velocitykm/smeta.id;meta.mainfloatO-CA[-1.4/1.9] Star A (O-C) residualkm/sstat.fit.residualfloatHRVB[-105.9/134.2] Star B heliocentric radial velocitykm/smeta.idfloatO-CB[-3.9/3.5] Star B (O-C) residualkm/sstat.fit.residualfloatJ/AJ/152/2/photometryCombined table from original tablesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintWebScopeWebScope identification (URSA or NFO)meta.id;instr.telcharHJDHeliocentric Julian Date (HJD-2400000) (1)dtime.epochdoubledVmag[0.772/1.7] The {Delta}V-band magnitude (2)magphot.mag;em.opt.VfloatJ/AJ/152/2/spectraCombined table from original tablesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintCompPrimary (hotter), or secondary (cooler) componentmeta.code.multipcharlambda[5033/6805] Spectrum wavelength (in {AA}) (1)0.1nmem.wldoubleFlux[0.464/1.017] Spectrum flux (normalized units) (1)phot.flux;arith.ratiodouble