J/A+A/601/A10ivo://CDS.VizieR/J/A+A/601/A10doi:10.26093/cds/vizier.36010010CDSVan Eck S.Neyskens P.Jorissen A.Plez B.Edvardsson B.Eriksson K.,Gustafsson B.Jorgensen U.G.Nordlund A.2018-11-13T13:15:03Z2017-04-19T12:50:01ZCDS support team

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

cds-question@unistra.frastronomical-modelsstellar-atmospheress-starslate-type-starsvisible-astronomynarrow-band-photometryinfrared-photometrybroad-band-photometrychemically-peculiar-starsS-type stars are late-type giants whose atmospheres are enriched in carbon and s-process elements because of either extrinsic pollution by a binary companion or intrinsic nucleosynthesis and dredge-up on the thermally-pulsing asymptotic giant branch. A grid of MARCS model atmospheres has been computed for S stars, covering the range 2700<=Teff(K)<=4000, 0.50<=C/O<0.99, 0<=logg<=5, [Fe/H]=0., -0.5dex, and [s/Fe]= 0, 1, and 2 dex (where the latter quantity refers to the global overabundance of s-process elements). The MARCS models make use of a new ZrO line list. Synthetic spectra computed from these models are used to derive photometric indices in the Johnson and Geneva systems, as well as TiO and ZrO band strengths. A method is proposed to select the model best matching any given S star, a non-trivial operation since the grid contains more than 3500 models covering a five-dimensional parameter space. The method is based on the comparison between observed and synthetic photometric indices and spectral band strengths, and has been applied on a vast subsample of the Henize sample of S stars. Our results confirm the old claim by Piccirillo (1980MNRAS.190..441P) that ZrO bands in warm S stars (Teff > 3200K) are not caused by the C/O ratio being close to unity, as traditionally believed, but rather by some Zr overabundance. The TiO and ZrO band strengths, combined with V-K and J-K photometric indices, are used to select Teff, C/O, [Fe/H] and [s/Fe]. The Geneva U-B_1 and B_2-V_1 indices (or any equivalent) are good at selecting the gravity. The defining spectral features of dwarf S stars are outlined, but none is found among the Henize S stars. More generally, it is found that, at Teff=3200K, a change of C/O from 0.5 to 0.99 has a strong impact on V-K (2mag). Conversely, a range of 2 mag in V-K corresponds to a 200K shift along the (Teff, V-K) relationship (for a fixed C/O value). Hence, the use of a (Teff, V-K) calibration established for M stars will yield large errors for S stars, so that a specific calibration must be used, as provided in the present paper. Using the atmospheric parameters derived by our method for the sample of Henize S stars, we show that the extrinsic-intrinsic dichotomy among S stars reveals itself very clearly as a bimodal distribution in the effective temperatures. Moreover, the increase of s-process element abundances with increasing C/O ratios and decreasing temperatures is apparent among intrinsic stars, confirming theoretical expectations.2017A&A...601A..10Vhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/601/A10CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/601/A10https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/601/A10http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/601/A10https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/601/A10https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/601/A10http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/601/A10GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/601/A10/table2 (Geneva and Johnson photometric indices and band indices for observed Henize S stars)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/601/A10/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/601/A10/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/601/A10/table2?GETtext/xml+votable180.050000true69.8450942-30.45661780.0055555555555555566/20492 20744 20768 24578 24689 24843 32793 32832 33909 34270 34665 36910 36913 37106 37183 37210 37245 37249 37255 37287 37299-37300 37302 37327 37334 37348 37352 37407 37442 37479 37484 37594 37690 37722 37813 37835 37864 37903 37922 37926 37947 37950 38023 38035 38044 38047 38051 38067 38080 38126 38405 38413 38429 38445 38472 38512 38569 38571 38679 38794 38802 38947 39161 39284 39289 39295 39303 39313 39315 39378 39414 39422 39451 39483 39599 39625 39655 39664 39729 39742 39762 39764 39780 39833 39847 39889 39937 39966 39988 40046 40071 40106 40450 40460 40960 41086 41417 41422 41494 41496 41569 41590 41625 41674 41685 41690 41693 41765 41791 41811 42123 42152 42208 42667 42850 42952 43028 43082 43092 43129 43150 43161 43170 43181 43258 43417 43546 43584 43667 43922 44042 44219https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/601/A10?format=asciiInfraredOpticaldefaultJ/A+A/601/A10/table1Boundaries of the continuum and band windows used in the computation of the band indicesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBandBand main contributorinstr.bandpasscharLBiInitial wavelength of the band interval (1)nmem.wlfloatLBfFinal wavelength band interval (1)nmem.wlfloatLCiInitial wavelength of the continuum interval(1)nmem.wlfloatLCfFinal wavelength of the continuum interval (1)nmem.wlfloatJ/A+A/601/A10/table2Geneva and Johnson photometric indices and band indices for observed Henize S starsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHen4-Hen 4-NNN: S stars from an unpublished list of Henize (1)meta.id;meta.maincharVmag0Dereddened Geneva V magnitude (2)magphot.mag;em.opt.VfloatAV? Total extinction at the V filtermagphys.absorptionfloatnullable(U-B)0Dereddened Geneva (U-B) color index (2)magphot.color;em.opt.U;em.opt.Bfloat(B-V)0Dereddened Geneva (B-V) color index (2)magphot.color.reddFree;em.opt.B;em.opt.Vfloat(V-K)0? Dereddened (V-K) color index (2)magphot.color;em.opt.V;em.IR.Kfloatnullable(J-K)0? Dereddened (J-K) color index (2)magphot.color;em.IR.J;em.IR.Kfloatnullable(H-K)0? Dereddened (H-K) color index (2)magphot.color;em.IR.H;em.IR.Kfloatnullable(K-L)0? Dereddened (K-L) color index (2)magphot.color.reddFreefloatnullable(U-B1)0Dereddened Geneva (U-B_1) color index (2)magphot.color.reddFree;em.opt.U;em.opt.Bfloat(B2-V1)0Dereddened Geneva (B_2-V_1) color index (2)magphot.color.reddFree;em.opt.B;em.opt.VfloatBTiOTitanium oxyde band strength index (2)meta.code;spect.indexfloatBZrOZirconium oxyde band strength index (2)meta.code;spect.indexfloatBNaSodium lines band strength index (2)meta.code;spect.indexfloatSimbadSimbad column added by the CDSmeta.ref.urlchar_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.mainJ/A+A/601/A10/table3Geneva and Johnson photometric indices and band indices computed on the grid of synthetic spectra of S starsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintTeffEffective temperatureKphys.temperature.effectiveintloggLogarithm (base 10) surface gravity (cgs)log(cm.s**-2)phys.gravityfloat[Fe/H]Metallicity (1)log(Sun)phys.abund.Zfloat[C/Fe]Abundance ratio [C/Fe] (1)log(Sun)phys.abund;arith.ratiofloatC/OCarbon to oxygen abundance ratiophys.abund;arith.ratiofloat[s/Fe]Abundance ratio [s/Fe] (1)(2)log(Sun)phys.abund;arith.ratiofloatU-B(U-B) color indexmagphot.color;em.opt.U;em.opt.BfloatB-V(B-V) color indexmagphot.color;em.opt.B;em.opt.VfloatV-R(V-R) color indexmagphot.color;em.opt.V;em.opt.RfloatR-I(R-I) color indexmagphot.color;em.opt.R;em.opt.IfloatV-K(V-K) color indexmagphot.color;em.opt.V;em.IR.KfloatJ-K(J-K) color indexmagphot.color;em.IR.J;em.IR.KfloatH-K(H-K) color indexmagphot.color;em.IR.H;em.IR.KfloatK-L(K-L) color indexmagphot.color;em.IR.K;em.IR.3-4umfloatBV_VBolometric correction in the V bandmagphot.mag.bcfloatBV_KBolometric correction in the K bandmagphot.mag.bcfloatU-B1(U-B_1) color index (Geneva)magphot.color;em.opt.U;em.opt.BfloatB2-V1(B_2-V_1) color index (Geneva)magphot.magfloatBTiOTitanium oxyde band strength index (2)meta.code;spect.indexfloatBZrOZirconium oxyde band strength index (2)meta.code;spect.indexfloatBNaSodium lines band strength index (2)meta.code;spect.indexfloat