J/A+A/531/A88ivo://CDS.VizieR/J/A+A/531/A88doi:10.26093/cds/vizier.35310088CDSUttenthaler S.Van Stiphout K.Voet K.Van Winckel H.Van Eck S.,Jorissen A.Kerschbaum F.Raskin G.Prins S.Pessemier W.,Waelkens C.Fremat Y.Hensberge H.Dumortier L.Lehmann H.2017-09-29T09:03:30Z2011-06-20T08:46:51ZCDS support team

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

cds-question@unistra.frvariable-starsspectroscopyMiras are long-period variables thought to be in the asymptotic giant branch (AGB) phase of evolution. In about one percent of known Miras, the pulsation period is changing. It has been speculated that this changing period is the consequence of a recent thermal pulse in these stars. We aim to clarify the evolutionary state of these stars, and to determine in particular whether or not they are in the thermally-pulsing (TP-)AGB phase. One important piece of information that has been neglected so far when determining the evolutionary state is the presence of the radio-active s-process element technetium (Tc). We obtained high-resolution, high signal-to-noise-ratio optical spectra of a dozen prominent Mira variables with changing pulsation period to search for this indicator of TPs and dredge-up. We also use the spectra to measure lithium (Li) abundances. Furthermore, we establish the evolutionary states of our sample stars by means of their present-day periods and luminosities. Among the twelve sample stars observed in this programme, five were found to show absorption lines of Tc. BH Cru is found to be a carbon-star, its period increase in the past decades possibly having stopped by now. We report a possible switch in the pulsation mode of T UMi from Mira-like to semi-regular variability in the past two years. R Nor, on the other hand, is probably a fairly massive AGB star, which could be true for all meandering Miras. Finally, we assign RU Vul to the metal-poor thick disk with properties very similar to the short-period, metal-poor Miras. We conclude that there is no clear correlation between period change type and Tc presence. The stars that are most likely to have experienced a recent TP are BH Cru and R Hya, although their rates of period change are quite different.2011A&A...531A..88Uhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/531/A88CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/531/A88https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/531/A88http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/531/A88https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/531/A88https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/531/A88http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/531/A88GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/531/A88/stars (Main properties of the studied Miras (from the table2 of the paper and Simbad))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/531/A88/stars?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/531/A88/stars?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/531/A88/stars?GETtext/xml+votable180.050000true184.07-56.2861110.0055555555555555566/11997 12925 15359 16132 22806 30606 32384 32622 42530 43150 43890 44018https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/531/A88?format=asciiOpticaldefaultJ/A+A/531/A88/starsMain properties of the studied Miras (from the table2 of the paper and Simbad)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintspPlot the spectrummeta.ref.urlcharFileNameName of the file containing the spectrummeta.id;meta.filecharNameSimbad name of the Mirameta.id;meta.maincharRAJ2000Simbad Hour of Right Ascension (J2000.0)pos.eq.ra;meta.mainDEJ2000Simbad Degree of Declination (J2000.0)pos.eq.dec;meta.mainPChPeriod change type: SCh, CCh or MCh (1)meta.notecharSpTRange of spectral typesrc.spType;instr.bandwidthcharHRVHeliocentric radial velocitykm/sspect.dopplerVeloc;pos.heliocentricfloatTc[yes no ?] Presence of Techneciummeta.notecharTeffEffective temperatureKphys.temperature.effectiveintl_LiLimit flag on Limeta.code.errorcharLiAbundance of Lithium (log{epsilon}(Li), H=12)phys.abundfloatPPeriod, this studydtime.periodfloatSimbadSimbad column added by the CDSmeta.refchar