J/MNRAS/493/6095ivo://CDS.VizieR/J/MNRAS/493/6095doi:10.26093/cds/vizier.74936095CDSMashonkina L.2025-02-20T20:15:55Z2023-10-04T08:05:00ZCDS support team

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

cds-question@unistra.fra-starschemical-abundancesvisible-astronomyA comprehensive model atom was developed for Si I-II-III using the most up-to-date atomic data available so far. Based on non-local thermodynamic equilibrium (NLTE) line formation for Si I, Si II and Si III and high-resolution observed spectra, we determined the NLTE abundances for a sample of nine unevolved A9-B3 type stars with well-determined atmospheric parameters. For each star, NLTE reduces the line-to-line scatter for Si II substantially compared with the LTE case and leads to consistent mean abundances from lines of different ionization stages. In the hottest star of our sample, {iota} Her, Si II is subject to overionization that drives emission in the lines arising from the high-excitation doublet levels. Our NLTE calculations reproduced 10 emission lines of Si II observed in {iota} Her. The same overionization effect leads to greatly weakened Si II lines, which are observed in absorption in {iota} Her. Large positive NLTE abundance corrections (up to 0.98dex for 5055{AA}) were useful for achieving consistent mean abundances from lines of the two ionization stages, Si II and Si III. It was found that NLTE effects are overestimated for the Si II 6347, 6371{AA} doublet in {iota} Her, while the new model atom works well for cooler stars. At this stage, we failed to understand this problem. We computed a grid of the NLTE abundance corrections for lines of Si I, Si II and Si III in model atmospheres with effective temperatures and surface gravities characteristic of unevolved A-B type stars.2020MNRAS.493.6095Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/493/6095CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/493/6095https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/493/6095http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/493/6095https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/493/6095https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/493/6095http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/493/6095GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/493/6095/table1 (Atmospheric parameters of the stars and mean NLTE and LTE abundances from lines of different ionization stages of silicon)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/493/6095/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/493/6095/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/493/6095/table1?GETtext/xml+votable180.050000true75.1658661-2.06603030.0055555555555555566/4698 9680 14906 19384 20940 21833 22917 30955 36651https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/493/6095?format=asciiOpticaldefaultJ/MNRAS/493/6095/table1Atmospheric parameters of the stars and mean NLTE and LTE abundances from lines of different ionization stages of siliconSimbadSimbad column added by the CDSmeta.ref.urlcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar name (HD NNNNNN)meta.id;meta.maincharONameAlternative namemeta.idcharTeffEffective temperatureKphys.temperature.effectiveintloggSurface gravitylog(cm.s**-2)phys.gravityfloat[Fe/H]Fe/H abundance ratiophys.abund.Fe;arith.ratiofloatvtMicroturbulent velocitykm/sphys.velocfloatRefReference for the star properties (1)meta.ref;pos.framecharNlSiI? Number of observed SiI linesmeta.numberintnullablelogeSiIN? Logarithm of the SiI NLTE abundancephys.abundfloatnullablee_logeSiIN? Error on logeSiINstat.errorfloatnullablelogeSiIL? Logarithm of the SiI LTE abundancephys.abundfloatnullablee_logeSiIL? Error on logeSiILstat.errorfloatnullableNlSiIINumber of observed SiII linesmeta.numberintlogeSiIINLogarithm of the SiII NLTE abundancephys.abundfloate_logeSiIINError on logeSiIINstat.errorfloatlogeSiIILLogarithm of the SiII LTE abundancephys.abundfloate_logeSiIILError on logeSiIILstat.errorfloatflag[2]? Flag on Error on logeSiIIN and logeSiIIL (2)meta.code.errorintnullableNlSiIII? Number of observed SiIII linesmeta.numberintnullablelogeSiIIIN? Logarithm of the SiIII NLTE abundancephys.abundfloatnullablee_logeSiIIIN? Error on logeSiIIINstat.errorfloatnullablelogeSiIIIL? Logarithm of the SiIII LTE abundancephys.abundfloatnullablee_logeSiIIIL? Error on logeSiIIILstat.errorfloatnullable[Si/H]Si/H abundance ratiophys.abundfloatf_[Si/H][1/3]? Flag on [Si/H] (2)meta.codeintnullable_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.main