J/MNRAS/361/1091ivo://CDS.VizieR/J/MNRAS/361/1091doi:10.26093/cds/vizier.73611091CDSNaylor T.Allan A.Long K.S.2024-07-01T20:15:01Z2005-11-18T19:07:51ZCDS support team

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

cds-question@unistra.freclipsing-binary-starswhite-dwarf-starsradial-velocityspectroscopyWe present a phase-resolved spectroscopic study of the secondary star in the cataclysmic variable (CV) U Gem. We use our data to measure the radial velocity semi-amplitude, systemic velocity and rotational velocity of the secondary star. Combining this with literature data allows us to determine masses and radii for both the secondary star and white dwarf, which are independent of any assumptions about their structure. We use these to compare their properties to those of field stars and find that both components follow field mass-radius relationships. The secondary star has the mass, radius, luminosity and photometric temperature of an M2 star, but a spectroscopic temperature of M4. The latter may well be due to a high metallicity. There is a troubling inconsistency between the radius of the white dwarf inferred from its gravitational redshift and inclination and that inferred from its temperature, flux and astrometric distance.2005MNRAS.361.1091Nhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/361/1091CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/361/1091https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/361/1091http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/361/1091https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/361/1091https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/361/1091http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/361/1091GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/361/1091/table2 (Measured parameters for 7 other stars)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/361/1091/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/361/1091/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/361/1091/table2?GETtext/xml+votable180.050000true185.75069164.0308310.0055555555555555566/811 3715 5000 10771 11255 23735 36526https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/361/1091?format=asciiOpticaldefaultJ/MNRAS/361/1091/table1Measured radial velocities from the Na I feature in the lower resolution spectra of U GemPhaseCalculated phase for the exposurefloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBJDBarycentric Julian Date for the middle of the exposureddoubleImageImage numberintRVRadial velocitykm/sinte_RVrms uncertainty on RV (1)km/sintSpectrumSpectrum filename in subdirectory "sp"charJ/MNRAS/361/1091/table2Measured parameters for 7 other stars_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.mainrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSpTypeMK spectral typecharNameNamechargammaAssumed gamma velocitykm/sintK2(NaI)Observed radial velocity semi-amplitude of the secondary star, K_2_, derived from NaI feature in the lower resolution spectrakm/sintK2(KI/TiO)Observed radial velocity semi-amplitude of the secondary star, K_2_, derived from KI/TiO feature in the lower resolution spectrakm/sintv2siniNaIBest-fitting value of the rotational velocity of the secondary star, v_2_sini derived from NaI feature in the lower resolution spectrakm/sintChi2NaI(Chi_nu_)^2^ associated to v2siniNaIfloatv2siniKI/TiOBest-fitting value of the rotational velocity of the secondary star, v_2_sini derived from NaI feature in the lower resolution spectrakm/sintChi2KI/TiO(Chi_nu_)^2^ associated to v2siniKI/TiOfloatv2siniNaIh? Best-fitting value of the rotational velocity of the secondary star, v_2_sini, derived from NaIh feature in the lower resolution spectrakm/sintnullableChi2NaIh? (Chi_nu_)^2^ associated to v2siniNaIhfloatnullablefNaIImplied fraction of the light originating from the secondary star in NaI lower resolution spectraintfKI/TiOImplied fraction of the light originating from the secondary star in KI/TiO lower resolution spectraintfNaIh? Implied fraction of the light originating from the secondary star in NaI higher resolution spectraintnullablegamma2NaIDerived mean velocity of the secondary star, gamma_2_, from NaI feature in the lower resolution spectra (1)km/sintgamma2KI/TiODerived mean velocity of the secondary star, gamma_2_ from KI/TiO feature in the lower resolution spectra (1)km/sintgamma2NaIh? Derived mean velocity of the secondary star, gamma_2_ from NaI feature in the higher resolution spectra (1)km/sintnullableSpectrumSpectrum filename in subdirectory "sp"charSimbadSimbad column added by the CDSchar_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main