J/A+A/676/A81ivo://CDS.VizieR/J/A+A/676/A81doi:10.26093/cds/vizier.36760081CDSZorec J.Hubert A.M.Martayan C.Fremat Y.2024-11-28T20:04:57Z2023-08-10T08:12:33ZCDS support team

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

cds-question@unistra.frbe-starseffective-temperaturestellar-massesstellar-agesvisible-astronomyThe search and interpretation of non-radial pulsations from Be star light curves observed with the CoRoT satellite requires to obtain high quality stellar astrophysical parameters. The present work is devoted to the spectroscopic study of a sample of faint Be stars observed by CoRoT in the fourth Long Run (LRA02). Astrophysical parameters are determined from spectra in the {lambda}{lambda}4000-4500{AA} wavelength domain observed with the VLT/FLAMES instruments at ESO. Spectra were fitted with models of stellar atmospheres using our GIRFIT package. Spectra obtained in the {lambda}{lambda}6400-7200{AA} wavelength domain enabled to identify or confirm the Be star candidates. The apparent parameters (Teff, logg, Vsini) of a set of 19 B and Be stars were corrected for the effects induced by the rapid rotation. They enabled to determine: i) stellar masses which are in agreement with those measured in detached binary systems; ii) spectroscopic distances that agree with the GAIA parallaxes; iii) centrifugal/gravity ~0.6-0.7 equatorial force ratios which indicate that our Be stars are under-critical rotators. The study of the Balmer Halpha, Hgamma and Hdelta emission lines produced: 1) extents of the circumstellar disc (CD) emitting regions that agree with the interferometric inferences in other Be stars; 2) R-dependent exponents n(R)=ln[rho(R)/rho_{sun}_]/ln(R_{sun}_/R) of the CD radial density distributions; 3) CD base densities rho_{sun}_ similar to those inferred in recent studies. The H{gamma} and H{delta} emission lines are formed in CD layers which are close to the central star. These lines produced a different value of the exponent n(R) than assumed for H{alpha}. Further detailed studies of H{gamma} and H{delta} emission lines could reveal the physical properties of regions where probably originate the viscous transport of angular momentum to the remaining CD regions. The under-critical rotation of Be stars suggests that their huge discrete mass-ejections and concomitant non-radial pulsations might have a common origin in stellar envelope regions that become unstable to convection due to rotation. If proven that the studied Be stars are products of binary mass transfer phases, the errors induced on the estimated Teff by the presence of stripped sub-dwarf O/B companions will probably not exceed their present uncertainties.2023A&A...676A..81Zhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/676/A81CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/A+A/613/A70 : Be stars in the exofield of CoRoT. II. (Semaan+, 2018)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/676/A81https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/676/A81http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/676/A81https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/676/A81https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/676/A81http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/676/A81GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/A+A/676/A81/tabled1Averaged parent-non-rotating-counterpart (pnrc) astrophysical parameters of the studied B and Be starsiInclination angledegsrc.orbital.inclination;pos.posAngintrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintWValue of the angular velocity ratio for the calculated rotational effects (1)phys.veloc.ang;arith.ratiofloatStar[1/19] Star number, within the W valuemeta.id;meta.mainintTeffParent-non-rotating-counterpart (pnrc) effective temperatureKphys.temperature.effectiveinte_TeffStandard deviation of TeffKstat.error;phys.temperature.effectiveintloggParent-non-rotating-counterpart (pnrc) surface gravitylog(cm.s**-2)phys.gravityfloate_loggStandard deviation of logglog(cm.s**-2)stat.errorfloatvsiniProjected rotational velocitykm/sphys.veloc.rotatinte_vsiniStandard deviation of the rotational velocitykm/sstat.error;phys.veloc.rotatintlogLParent-non-rotating-counterpart (pnrc) bolometric luminositylog(solLum)phys.luminosityfloate_logLStandard deviation of the bolometric luminositylog(solLum)stat.errorfloatMParent-non-rotating-counterpart (pnrc) stellar masssolMassphys.massfloate_MStandard deviation of the stellar masssolMassstat.errorfloatVcEquatorial linear critical velocitykm/sphys.velocinte_VcStandard deviation of the critical velocitykm/sstat.error;pos.cartesian.yinte_iStandard deviation of the inclination angledegstat.errorintt/tMSFractional stellar agetime.agefloate_t/tMSStandard deviation of the fractional agestat.errorfloattStellar ageyrtime.agedoublee_tStandard deviation of the stellar ageyrstat.errordoublenuRotational frequency (cycle/day)c.d**-1phys.veloc.rotatfloate_nuStandard deviation of the rotational frequencyc.d**-1stat.errorfloatJ/A+A/676/A81/tabled2Modes of distributions of parent-non-rotating-counterpart (pnrc) astrophysical parameters of the studied B and Be starsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintWValue of the angular velocity ratio for the calculated rotational effects (1)phys.veloc.ang;arith.ratiofloatStar[1/19] Star number, within the W valuemeta.id;meta.mainintTeffParent-non-rotating-counterpart (pnrc) effective temperatureKphys.temperature.effectiveinte_TeffStandard deviation of TeffKstat.error;phys.temperature.effectiveintloggParent-non-rotating-counterpart (pnrc) surface gravitylog(cm.s**-2)phys.gravityfloate_loggStandard deviation of logglog(cm.s**-2)stat.errorfloatvsiniProjected rotational velocitykm/sphys.veloc.rotatinte_vsiniStandard deviation of the rotational velocitykm/sstat.error;phys.veloc.rotatintlogLParent-non-rotating-counterpart (pnrc) bolometric luminositylog(solLum)phys.luminosityfloate_logLStandard deviation of the bolometric luminositylog(solLum)stat.errorfloatMParent-non-rotating-counterpart (pnrc) stellar masssolMassphys.massfloate_MStandard deviation of the stellar masssolMassstat.errorfloatVcEquatorial linear critical velocitykm/sphys.velocinte_VcStandard deviation of the critical velocitykm/sstat.error;pos.cartesian.yintiInclination angledegsrc.orbital.inclination;pos.posAnginte_iStandard deviation of the inclination angledegstat.errorintt/tMSFractional stellar agetime.agefloate_t/tMSStandard deviation of the fractional agestat.errorfloattStellar ageyrtime.agedoublee_tStandard deviation of the stellar ageyrstat.errordoublenuRotational frequency (cycle/day)c.d**-1phys.veloc.rotatfloate_nuStandard deviation of the rotational frequencyc.d**-1stat.errorfloat