J/A+A/686/A304ivo://CDS.VizieR/J/A+A/686/A304doi:10.26093/cds/vizier.36860304CDSBeuermann K.Reinsch K.2024-11-29T20:03:19Z2024-06-21T09:02:18ZCDS support team

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

cds-question@unistra.frspectroscopic-binary-starscataclysmic-variable-starsspectroscopyultraviolet-astronomyvisible-astronomyEX Hya is one of the best studied, but still enigmatic intermediate polars. We present phase-resolved blue VLT/UVES high-resolution ({lambda}/{DELTA}{lambda}~=16.000) spectra of EX Hya taken in January 2004. Our analysis involves a unique decomposition of the Balmer line profiles into the spin-modulated line wings that represent streaming motions in the magnetosphere and the orbital-phase modulated line core that represents the accretion disk. Spectral analysis and tomography show that the division line between the two is solidly located at |v_rad_|~=1200km/s, defining the inner edge of the accretion disk at r_in_=~7x10^9^cm or ~10R1 (WD radii). This large central hole allows an unimpeded view of the tall accretion curtain at the lower pole with a shock height up to h_sh_~1R1 that is required by X-ray and optical observations. Our results contradict models that advocate a small magnetosphere and a small inner disk hole. Equating rin with the magnetospheric radius in the orbital plane allows us to derive a magnetic moment of the WD of {mu}1~=1.3x10^32^G.cm^3^ and a surface field strength B1~0.35MG. Given a polar field strength Bp~<1.0MG, optical circular polarization is not expected. With an accretion rate dM/dt=3.9x10^-11^M_{sun}_/yr, the accretion torque is Gacc~=2.2x10^33^g.cm^2^/s^2^. The magnetostatic torque is of similar magnitude, suggesting that EX Hya is not far from being synchronized. We measured the orbital radial-velocity amplitude of the WD, K1=58.7+/-3.9km/s, and found a spin-dependent velocity modulation as well. The former is in perfect agreement with the mean velocity amplitude obtained by other researchers, confirming the published component masses M1~=0.79M_{sun}_ and M2~=0.11M_{sun}_ .2024A&A...686A.304Bhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/686/A304CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/MNRAS/461/1576 : EX Hya mid-eclipse timings (Echevarria+, 2016)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/686/A304https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/686/A304http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/686/A304https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/686/A304https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/686/A304http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/686/A304GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapUVOpticaldefaultJ/A+A/686/A304/phasesOrbital and spin phases of the spectrarecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintnoExposure numbermeta.idintObs.dateDatestime.epochnullableAMAirmassobs.airMassfloatBJDBarycentric Julian Date, TDB (BJD-2400000)dtime.epochdoublephi98Orbital phase (G1)time.phasedoublephi67Spin phase (G2)time.phasedoubleminFlag (1)meta.codeintmaxFlag (1)meta.codeintspShow the spectrummeta.ref.urlcharFileNameFilename of the spectrum, in subdirectory fitsmeta.id;meta.filecharJ/A+A/686/A304/vradcaiiCaII8498.020 radial velocitiesvobsMeasured radial velocity (G3)km/sphys.veloc;pos.heliocentricfloate_vobsError of vobskm/sstat.errorfloatwWeightstat.weight;phys.atmol.weightintvmodModelled radial velocity (1)km/sspect.dopplerVeloc;meta.modelledfloatiIndexmeta.idintrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintphiHSOrbital phase (G1)time.phasefloatJ/A+A/686/A304/vradfeiFeI4957.596 radial velocitiesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintiIndexmeta.idintphiHSOrbital phase (G1)time.phasefloatvobsMeasured radial velocity (G3)km/sphys.veloc;pos.heliocentricfloate_vobsError of v_obskm/sstat.errorfloatwWeightstat.weight;phys.atmol.weightintvmodModelled radial velocity (2)km/sspect.dopplerVeloc;meta.modelledfloatJ/A+A/686/A304/vradsiiSi3905.527 radial velocitiesiIndexmeta.idintrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintphiHSOrbital phase (G1)time.phasefloatvobsMeasured radial velocity (G3)km/sphys.veloc;pos.heliocentricfloate_vobsError of vobskm/sstat.errorfloatwWeightstat.weight;phys.atmol.weightintvmodModelled radial velocity (3)km/sspect.dopplerVeloc;meta.modelledfloatJ/A+A/686/A304/vrhbetaRadial velocities from the Hbeta linerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintObs.dateObservation datetime.epoch;obsnullableSeqSequence number within obs. nightmeta.idintvradRadial velocity (G4)km/sphys.veloc;pos.heliocentricfloate_vradError of vradkm/sstat.errorfloatphi98Orbital phase (G1)time.phasefloatphi67Spin phase (G2)time.phasefloatincl[0/1] Flag (G4)meta.codeintJ/A+A/686/A304/vrhgammaRadial velocities from the Hgamma linerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintObs.dateObservation datetime.epoch;obsnullableSeqSequence number within obs. nightmeta.idintvradRadial velocity (G4)km/sphys.veloc;pos.heliocentricfloate_vradError of vradkm/sstat.errorfloatphi98Orbital phase (G1)time.phasefloatphi67Spin phase (G2)time.phasefloatincl[0/1] Flag (G4)meta.codeint