J/A+A/589/A1ivo://CDS.VizieR/J/A+A/589/A1doi:10.26093/cds/vizier.35890001CDSRandall S.K.Calamida A.Fontaine G.Monelli M.Bono G.Alonso M.L.,Van Grootel V.Brassard P.Chayer P.Catelan M.Littlefair S.,Dhillon V.S.Marsh T.R.2018-05-11T15:19:50Z2016-04-04T06:49:30ZCDS support team

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

cds-question@unistra.frglobular-star-clustershorizontal-branch-starsphotometryspectroscopyWe present the results of an extensive survey for rapid pulsators among Extreme Horizontal Branch (EHB) stars in {omega} Cen. The observations performed consist of nearly 100 hours of time-series photometry for several off-centre fields of the cluster, as well as low-resolution spectroscopy for a partially overlapping sample. We obtained photometry for some 300 EHB stars, for aro und half of which we are able to recover light curves of sufficient quality to either detect or place meaningful non-detection limits for rapid pulsations. Based on the spectroscopy, we derive reliable values of logg, Teff and logN(He)/N(H) for 38 targets, as well as good estimates of the effective temperature for another nine targets, whose spectra are slightly polluted by a close neighbour in the image. The survey uncovered a total of five rapid variables with multi-periodic oscillations between 85 and 125s. Spectroscopically, they form a homogeneous group of hydrogen-rich subdwarf O stars clustered between 48000 and 54000K. For each of the variables we are able to measure between two and three significant pulsations believed to constitute independent harmonic oscillations. However, the interpretation of the Fourier spectra is not straightforward due to significant fine structure attributed to strong amplitude variations. In addition to the rapid variables, we found an EHB star with an apparently periodic luminosity variation of ~2700s, which we tentatively suggest may be caused by ellipsoidal variations in a close binary.2016A&A...589A...1Rhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/589/A1CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/589/A1https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/589/A1http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/589/A1https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/589/A1https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/589/A1http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/589/A1GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/589/A1/table5 (Atmospheric parameters inferred for our FORS2 spectroscopic 47 EHB stars with clean or slightly polluted spectra.)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/589/A1/table5?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/589/A1/table5?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/589/A1/table5?GETtext/xml+votable180.050000true201.60383333-47.424716670.0055555555555555566/43225 432273.8814057807558857e-19 4.826256797203527e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/589/A1?format=asciidefaultJ/A+A/589/A1/table5Atmospheric parameters inferred for our FORS2 spectroscopic 47 EHB stars with clean or slightly polluted spectra.SimbadNameSimbad column added by the CDSmeta.idcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintspfcShow the flux-calibrated spectrummeta.ref.urlcharspsShow the non-flux-calibrated spectrummeta.ref.urlcharNameStar identification numbermeta.id;meta.mainintn_Name[*] Note on Name (1)meta.notecharRAJ2000Right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Declination (J2000)pos.eq.dec;meta.mainTeffEffective temperatureKphys.temperature.effectiveinte_Teffrms uncertainty on TeffKstat.error;phys.temperature.effectiveintloggSuface gravitylog(cm.s**-2)phys.gravityfloate_loggrms uncertainty on logglog(cm.s**-2)stat.errorfloatlog(He/H)Abundance He/Hphys.abund.Yfloate_log(He/H)rms uncertainty on log(He/H)stat.errorfloatr_Bmag[ACS/WFI] Instrument for Bmag and Rmagmeta.ref;pos.framecharBmagACS/WFI B magnitudemagphot.mag;em.opt.Bfloate_Bmagrms uncertainty on Bmagmagstat.error;phot.mag;em.opt.BfloatRmagACS/WFI R magnitudemagphot.mag;em.opt.Rfloate_Rmagrms uncertainty on Rmagmagstat.error;phot.mag;em.opt.RfloatPhotInstrument used for photometrymeta.id;instrcharDet? Detection limit above which pulsations would have been detected for the targets that overlap with our time-series photometry sample%instr.sensitivityfloatnullableONameOther name (2)meta.idcharn_OName[** ] Note on OName (1)meta.notechar