J/A+A/652/A70ivo://CDS.VizieR/J/A+A/652/A70doi:10.26093/cds/vizier.36520070CDSBodensteiner J.Sana H.Wang C.Langer N.Mahy L.Banyard G.,de Koter A.de Mink S.E.Evans C.J.Goetberg Y.Patrick L.R.,Schneider F.R.N.Tramper F.2023-02-08T11:45:00Z2021-08-12T09:18:31ZCDS support team

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

cds-question@unistra.frmagellanic-cloudsopen-star-clustersstellar-populationsradial-velocityObservations of massive stars in open clusters younger than 8 Myr have shown that a majority of them are in binary systems, most of which will interact during their life. While these can be used as a proxy of the initial multiplicity properties, studying populations of massive stars older than ~20Myr allows us to probe the outcome of such interactions after a significant number of systems have experienced mass and angular momentum transfer and possibly even merged. Using multi-epoch integral-field spectroscopy, we aim to investigate the multiplicity properties of the massive-star population in the dense core of the ~40Myr-old cluster NGC 330 in the Small Magellanic Cloud in order to search for possible imprints of stellar evolution on the multiplicity properties. We obtained six epochs of VLT/MUSE observations operated in wide-field mode with the extended wavelength setup and supported by adaptive optics.We extract spectra and measure radial velocities for stars brighter than m_F814W_=19. We identify single-lined spectroscopic binaries through significant RV variability with a peak-to-peak amplitude larger than 20km/s. We also identify double-lined spectroscopic binaries, and quantify the observational biases for binary detection. In particular, we take into account that binary systems with similar line strength are difficult to detect in our data set. The observed spectroscopic binary fraction among the stars brighter than m_F814W_=19 (~5.5M_{sun}_ on the main sequence) is f^obs^_SB_=13.2+/-2:0%. Considering period and mass ratio ranges from log(P)=0.15-3.5 (about 1.4 to 3160d), and q=0.1-1.0, and a representative set of orbital parameter distributions, we find a bias-corrected close binary fraction of f_cl_=34^+8^_-7_%. This fraction seems to decline for the fainter stars, which indicates either that the close binary fraction drops in the B-type domain, or that the period distribution becomes more heavily weighted towards longer orbital periods.We further find that both fractions vary strongly in different regions of the color-magnitude diagram that corresponds to different evolutionary stages. This probably reveals the imprint of the binary history of different groups of stars. In particular, we find that the observed spectroscopic binary fraction of Be stars (f^obs^_SB_=2+/-2%) is significantly lower than the one of B-type stars (f^obs^_SB_=9+/-2%). In this work we provide the first homogeneous RV study of a large sample of B-type stars at a low metallicity ([Fe/H]<~-1.0). The overall bias-corrected close binary fraction (log(P)<3.5d) of the B-star population in NGC 330 is lower than the one reported for younger Galactic and LMC clusters in previous works. More data are, however, needed to establish whether the observed differences result from an age or a metallicity effect.2021A&A...652A..70Bhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/652/A70CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/634/A51 : NGC 330 seen by MUSE (Bodensteiner+, 2020)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/652/A70https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/652/A70http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/652/A70https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/652/A70https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/652/A70http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/652/A70GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/652/A70/tablec1 (Compilation of all parameters derived for the stars)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/652/A70/tablec1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/652/A70/tablec1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/652/A70/tablec1?GETtext/xml+votable180.050000true14.07891306-72.472821940.0055555555555555566/333172.0401237512456292e-19 2.706461185444514e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/652/A70?format=asciidefaultJ/A+A/652/A70/tablec1Compilation of all parameters derived for the starsF814WF814W magnitude from Milone et al., (2018MNRAS.477.2640M)magphot.mag;em.opt.IfloatSpTypeSpectral typesrc.spTypecharlinesLine used (1)instr.setup;spect.linecharRV1? Radial velocity for epoch 1 (2017-08-15)km/sspect.dopplerVelocfloatnullablee_RV1? rms uncertainty on RV1km/sstat.errorfloatnullableRV2? Radial velocity for epoch 2 (2017-09-18)km/sspect.dopplerVelocfloatnullableSimbadSimbad column added by the CDSmeta.ref.urlchare_RV2? rms uncertainty on RV2km/sstat.errorfloatnullableRV3? Radial velocity for epoch 3 (2018-11-06)km/sspect.dopplerVelocfloatnullablee_RV3? rms uncertainty on RV3km/sstat.errorfloatnullableRV4? Radial velocity for epoch 4 (2018-11-19)km/sspect.dopplerVelocfloatnullablee_RV4? rms uncertainty on RV4km/sstat.errorfloatnullableRV5? Radial velocity for epoch 5 (2018-11-22)km/sspect.dopplerVelocfloatnullablee_RV5? rms uncertainty on RV5km/sstat.errorfloatnullableRV6? Radial velocity for epoch 6 (2018-12-18)km/sspect.dopplerVelocfloatnullablee_RV6? rms uncertainty on RV6km/sstat.errorfloatnullableFlagFlag (2)meta.code.errorcharComCommentsmeta.notecharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintID[10/732] Identification numbermeta.id;meta.mainintRAJ2000Right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Declination (J2000)degpos.eq.dec;meta.main