J/A+A/667/A85ivo://CDS.VizieR/J/A+A/667/A85doi:10.26093/cds/vizier.36670085CDSCrawford C.L.Tisserand P.Clayton G.C.Munson B.2024-06-05T16:27:13Z2022-11-09T07:35:25ZCDS support team

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

cds-question@unistra.frcarbon-starsline-intensitiesvisible-astronomyR Coronae Borealis (RCB) variables and their non-variable counterparts, the dustless Hydrogen-Deficient Carbon (dLHdC) stars have been known to exhibit enhanced s-processed material on their surfaces, especially Sr, Y, and Ba. No comprehensive work has been done to explore the s-process in these types of stars, however one particular RCB star, U Aqr, has been under scrutiny for its extraordinary Sr enhancement. We aim to identify RCB and dLHdC stars that have significantly enhanced Sr abundances, such as U Aqr, and use stellar evolution models to begin to estimate the type of neutron exposure that occurs in a typical HdC star. We compare the strength of the SrII 4077{AA} spectral line to CaII H to identify the new subclass of Sr-rich HdCs. We additionally use the structural and abundance information from existing RCB MESA models to calculate the neutron exposure parameter, {tau}. We identify six stars in the Sr-rich class. Two are RCBs, and four are dLHdCs. We additionally find that the preferred RCB MESA model has a neutron exposure {tau}~=0.1mb^-1^, which is lower than the estimated between 0.15 and 0.6mb^-1^ for the Sr-rich star U Aqr found in the literature. We find trends in the neutron exposure corresponding to He-burning shell temperature, metallicity, and assumed s-processing site. We have found a sub-class of 6 HdCs known as the Sr-rich class, which tend to lie in the halo, outside the typical distribution of RCBs and dLHdCs. We find that dLHdC stars are more likely to be Sr-rich than RCBs, with an occurrence rate of ~13% for dLHdCs and ~2% for RCBs. This is one of the first potential spectroscopic differences between RCBs and dLHdCs, along with dLHdCs having stronger surface abundances of 18O. We additionally find neutron exposure trends in our RCB models that will aide in understanding the interplay between model parameters and surface s-process elements.2022A&A...667A..85Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/667/A85CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toMay/22 : Hydrogen-deficient Carbon stars spectra (Tisserand+, 2022)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/667/A85https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/667/A85http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/667/A85https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/667/A85https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/667/A85http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/667/A85GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/667/A85/pews (Pseudo-equivalent widths of HdC spectral features)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/667/A85/pews?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/667/A85/pews?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/667/A85/pews?GETtext/xml+votable180.050000true263.901187250.41107310.0055555555555555566/8701 9720 12239 12842 14307 14546 14626 15065 24935 28678 28690 28712 28717-28719 28726 28735 28769 28774-28775 28783 28785 28805 28834 28836 28838 28842 28844 28849 28857 28870 28872 28881 28887 28893 28902 28904-28905 28907-28909 28911 28970 29000 29005 29052 29080 29083 29089 29111 29136 29168 29170 29173 29178 29184 29194 29210 29214 29217 29244 29252 29255 29261 29303 29442 29449 29464 29604 29635 29841 30122 30171 30208 30222 30239 30282 30383 30637 30650 30740 32023 32076 33047 33055 33088 33090 33095 33103 33120 33294-33295 33327 37408 37418 37929 38333 40272 41178 41279 41438 41462 41471 41535 41630 41718 41788 42139 42186 42192 42194 42203 42218 42300 42335 42337 42341 42359 42367 42399 42479 42481 42491 42506 42556 42692 42759 42820 43161 43378 44328 45693 46004 47661 47814 47869 47895 47919 48038 48507 48801https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/667/A85?format=asciiOpticaldefaultJ/A+A/667/A85/pewsPseudo-equivalent widths of HdC spectral featuresSimbadNameSimbad column added by the CDSmeta.idcharnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar namemeta.id;meta.maincharCah? Pseudo-EW for Ca II H (1)0.1nmspect.line.eqWidthfloatnullableCak? Pseudo-EW for Ca II K (1)0.1nmspect.line.eqWidthfloatnullableSr4077? Pseudo-EW for Sr II 4077 line (1)0.1nmspect.line.eqWidthfloatnullableBa4554? Pseudo-EW for Ba II 4554 line (1)0.1nmspect.line.eqWidthfloatnullable_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