J/A+A/690/A393ivo://CDS.VizieR/J/A+A/690/A393doi:10.26093/cds/vizier.36900393CDSUttenthaler S.Shetye S.Nanni A.Aringer B.Eriksson K.McDonald I.,Gobrecht D.Hoefner S.Wolter U.Cristallo S.Bernhard K.2025-02-18T20:01:33Z2024-10-24T19:11:07ZCDS support team

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

cds-question@unistra.frvariable-starslate-type-starsm-starsinfrared-astronomyspectroscopyvisible-astronomyThe details of the mass-loss process in the late stages of low- and intermediate-mass stellar evolution are not well understood, in particular its dependence on stellar parameters. Mira variables are highly suitable targets for studying this mass-loss process. Here, we follow up on our earlier finding that a near-to-mid-infrared (NIR-MIR) colour versus pulsation period diagram shows two sequences of Miras that can be distinguished by the third dredge-up (3DUP) indicator technetium in those stars. While IR colours are good indicators of the dust mass-loss rate (MLR) from Miras, no corresponding sequences have been found using the gas MLR. However, investigations of the gas MLR have been hampered by data limitations. We aim to alleviate these limitations with new observational data. We present new optical spectra of a well-selected sample of Miras. We searched these spectra for absorption lines of Tc and other 3DUP indicators, and combine our findings with gas MLRs and expansion velocities from the literature. Furthermore, we extend the analysis of the MIR emission to WISE data and compare the broadband spectral energy distributions (SEDs) of Miras with and without Tc. We find no systematic difference in gas MLRs between Miras with and without Tc. However, the gas envelopes of Tc-poor Miras appear to have a higher terminal expansion velocity than those of Miras with Tc. Furthermore, our analysis of the IR photometry strongly corroborates the earlier finding that Tc-poor Miras have a higher MIR emission than Tc-rich ones, by as much as a factor of two.We model the IR colours with DARWIN and stationary wind models and conclude that Miras with and without Tc have different dust content or dust properties. We discuss several hypotheses and interpretations of the observations and conclude that the reduction of free oxygen by 3DUP of carbon and iron-depleted dust grains in Tc-rich stars are the most convincing explanations for our observations.2024A&A...690A.393Uhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/690/A393CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/690/A393https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/690/A393http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/690/A393https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/690/A393https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/690/A393http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/690/A393GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tap7.952274030004205e-20 1.0188844282367877e-19OpticalInfrareddefaultJ/A+A/690/A393/table2Observational results and parameters of the new starsNameVariable namemeta.id;meta.maincharRefReference for the gas MLR and v1 (1)meta.ref;pos.framecharspShow the spectrummeta.ref.urlcharSpName of the table with spectrum datameta.id;meta.filecharspFits? Number of fits spectrameta.numberintnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintTcTc content (0 = Tc absent, 1 = Tc present)meta.codecharHRV? Heliocentric radial velocitykm/sspect.dopplerVeloc;pos.heliocentricfloatnullablePerPulsation perioddtime.periodintSpTypeSpectral typesrc.spTypecharKsmagMean KS-band magnitudemagphot.mag;em.IR.KfloatW4magWISE 4 magnitudemagphot.flux.density;em.IR.15-30umfloatdMgas/dtGas mass-loss ratesolMass/yrphys.mass.lossdoublev1Terminal expansion velocitykm/sphys.veloc.expansionfloatJ/A+A/690/A393/listList of fits HEROS/TIGRE spectraTitleTitle of the FITS filemeta.title;meta.fitscharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameVariable namemeta.id;meta.maincharNxNumber of pixels along X-axismeta.numberintObs.dateObservation datestime.epoch;obsnullableblambdaLower value of wavelength interval0.1nmem.wlfloatBblambdaUpper value of wavelength interval0.1nmem.wlfloatdblambdaWavelength resolution0.1nmspect.resolutiondoublesizeSize of FITS fileKibytephys.size;meta.fitsintSpShow the spectrummeta.ref.urlcharFileNameName of FITS file, in subdirectory fitsmeta.id;meta.fitscharJ/A+A/690/A393/raurR Aur HERMES/Mercator spectrumrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaWavelength0.1nmem.wldoubleFlux? Flux in arbitrary unitsphot.fluxdoublenullableJ/A+A/690/A393/rcasR Cas HERMES/Mercator spectrumrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintFlux? Flux in arbitrary unitsphot.fluxdoublenullablelambdaWavelength0.1nmem.wldoubleJ/A+A/690/A393/uaurU Aur HERMES/Mercator spectrumrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaWavelength0.1nmem.wldoubleFlux? Flux in arbitrary unitsphot.fluxdoublenullableJ/A+A/690/A393/uherU Her HERMES/Mercator spectrumlambdaWavelength0.1nmem.wldoubleFlux? Flux in arbitrary unitsphot.fluxdoublenullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintJ/A+A/690/A393/wycasWY Cas HERMES spectrumrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambdaWavelength0.1nmem.wldoubleFlux? Flux in arbitrary unitsphot.fluxdoublenullable