J/MNRAS/542/2768ivo://CDS.VizieR/J/MNRAS/542/2768CDSKamann S.Bastian N.Niederhofer F.Bellini A.Cabrera-Ziri I.,Dreizler S.Goettgens F.Kozhurina-Platais V.Libralato M.Martens S.,Saracino S.2025-09-15T10:59:41Z2025-09-15T11:43:47ZCDS support team

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

cds-question@unistra.frmagellanic-cloudsstellar-associationsspectroscopyvisible-astronomyradial-velocityWe present a detailed analysis of stellar rotation along the main sequences of NGC 1866 and NGC 1856, two young (~200-300Myr) massive clusters in the Large Magellanic Cloud, using MUSE integral field spectroscopy. Differences in stellar rotation have been proposed as an explanation for the extended main sequence turn-offs and split main sequences in these clusters. In agreement with this idea, we find strong links between the photometric colours of the cluster stars and their projected rotation velocities, Vsini. While stars blueward of the split main sequences are characterized by a range of relatively low spins, those with redder colours are fast rotators. Following a statistical correction for inclination, we measure mean equatorial velocities for the red main-sequence stars in both clusters of Veq=300km/s, corresponding to 70-80% of the critical values predicted for such stars by current stellar models. We discuss these findings in the context of the different scenarios proposed to explain the stellar rotation distributions of young massive clusters. We further investigate whether the high rotation rates provide a natural explanation for the high fractions of Be stars we observe in both clusters, peaking at >=50% at the turn-off. We argue that if ~85% of the critical rotation rate is high enough to trigger the formation of a decretion disk, most upper main sequence stars in the clusters are expected to become Be stars before leaving the main sequence.2025MNRAS.542.2768Khttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/542/2768CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/A+A/689/A162 : Astro-photometry of 23 LMC clusters (Niederhofer+, 2024)J/A+A/618/A25 : Model stellar spectra for B to early-M (Allende Prieto+, 2018)https://gitlab.gwdg.de/skamann/pampelmuse : PampelMuse spectrum extractionhttps://github.com/thusser/spexxy : Spexxy spectral analysis softwarehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/542/2768https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/542/2768http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/542/2768https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/542/2768https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/542/2768http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/542/2768GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/MNRAS/542/2768/ngc1856Spectral analysis results for NGC 1856recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintspShow the spectrummeta.ref.urlcharFileNameName of FITS spectrum (1)meta.id;meta.filecharVel? Heliocentric line-of-sight velocity (STAR.V)km/sspect.dopplerVeloc;pos.heliocentricdoublenullablee_Vel? Nominal uncertainty of Vel measurement (STAR.V.ERR)km/sstat.errordoublenullablevsini? Projected stellar rotation velocity (STAR.VSINI)km/sphys.veloc.rotatdoublenullablee_vsini? Nominal uncertainty of vsini measurement (STAR.VSINI.ERR)km/sstat.error;phys.veloc.rotatdoublenullableepsilon[0.8] Constant linear limb-darkening parameter adopted during spectral fit (STAR.EPSILON)stat.fit.paramfloat[Fe/H]Scaled-solar metallicity, either derived via isochrone comparison or spectral fit (STAR.FEH)phys.abund.Zdoublee_[Fe/H]? Nominal uncertainty for [Fe/H] when derived via spectral fit (STAR.FEH.ERR)stat.error;phys.abund.FedoublenullablelogVDOP[0] Constant microturbulence adopted during spectral fit (STAR.LOG10VDOP)stat.fit.paramfloatTeffEffective temperature (STAR.TEFF)Kphys.temperature.effectivedoublee_Teff? Nominal uncertainty of Teff measurement (STAR.TEFF.ERR)Kstat.error;phys.temperature.effectivedoublenullableloggSurface gravity, either derived via isochrone comparison or spectral fit (STAR.LOGG)log(cm.s**-2)phys.gravitydoublee_logg[0] Nominal uncertainty for logg when derived via spectral fit (STAR.LOGG.ERR)log(cm.s**-2)stat.errorfloatSuccess[False True] Flag indicating a formally successful spexxy fit (Success)meta.codecharrchi2Reduced chi square of spexxy fit (RedChi2)stat.fit.chi2doubleoriginType of spectral fit, depending on output of isochrone comparison and emission-line analysis (origin) (2)meta.notecharBe[False True] Flag indicating if star is considered a Be star (be)meta.codecharshell[False True] Flag indicating if star is considered a shell star (shell)meta.codecharN24Id[1906/80619]? ID of stari, within the cluster, in Niederhofer et al. (2024A&A...689A.162N, Cat. J/A+A/689/A162) where available (Niederhofer.ID)meta.idintnullableJ/MNRAS/542/2768/ngc1866Spectral analysis results for NGC 1866recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintVel? Heliocentric line-of-sight velocity (STAR.V)km/sspect.dopplerVeloc;pos.heliocentricdoublenullablee_Vel? Nominal uncertainty of Vel measurement (STAR.V.ERR)km/sstat.errordoublenullablevsini? Projected stellar rotation velocity (STAR.VSINI)km/sphys.veloc.rotatdoublenullablee_vsini? Nominal uncertainty of vsini measurement (STAR.VSINI.ERR)km/sstat.error;phys.veloc.rotatdoublenullableepsilon[0.8] Constant linear limb-darkening parameter adopted during spectral fit (STAR.EPSILON)stat.fit.paramfloat[Fe/H]Scaled-solar metallicity, either derived via isochrone comparison or spectral fit (STAR.FEH)phys.abund.Zdoublee_[Fe/H]? Nominal uncertainty for [Fe/H] when derived via spectral fit (STAR.FEH.ERR)stat.error;phys.abund.FedoublenullablelogVDOP[0] Constant microturbulence adopted during spectral fit (STAR.LOG10VDOP)stat.fit.paramfloatTeffEffective temperature (STAR.TEFF)Kphys.temperature.effectivedoublee_Teff? Nominal uncertainty of Teff measurement (STAR.TEFF.ERR)Kstat.error;phys.temperature.effectivedoublenullableloggSurface gravity, either derived via isochrone comparison or spectral fit (STAR.LOGG)log(cm.s**-2)phys.gravitydoublee_logg[0] Nominal uncertainty for logg when derived via spectral fit (STAR.LOGG.ERR)log(cm.s**-2)stat.errorfloatSuccess[False True] Flag indicating a formally successful spexxy fit (Success)meta.codecharrchi2Reduced chi square of spexxy fit (RedChi2)stat.fit.chi2doubleoriginType of spectral fit, depending on output of isochrone comparison and emission-line analysis (origin) (2)meta.notecharBe[False True] Flag indicating if star is considered a Be star (be)meta.codecharshell[False True] Flag indicating if star is considered a shell star (shell)meta.codecharN24Id[1906/80619]? ID of stari, within the cluster, in Niederhofer et al. (2024A&A...689A.162N, Cat. J/A+A/689/A162) where available (Niederhofer.ID)meta.idintnullablespShow the spectrummeta.ref.urlcharFileNameName of FITS spectrum (1)meta.id;meta.filechar