J/MNRAS/421/2798ivo://CDS.VizieR/J/MNRAS/421/2798doi:10.26093/cds/vizier.74212798CDSDeca J.Marsh T.R.Ostensen R.H.Morales-Rueda L.Copperwheat C.M.,Wade R.A.Stark M.A.Maxted P.F.L.Nelemans G.Heber U.2024-07-17T20:15:13Z2013-04-11T12:22:53ZCDS support team

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

cds-question@unistra.frspectroscopic-binary-starssubdwarf-starsradial-velocityAbout 50 per cent of all known hot subdwarf B stars (sdBs) reside in close (short-period) binaries, for which common-envelope ejection is the most likely formation mechanism. However, Han et al. (2002MNRAS.336..449H, 2003MNRAS.341..669H) predict that the majority of sdBs should form through stable mass transfer leading to long-period binaries. Determining orbital periods for these systems is challenging and while the orbital periods of ~100 short-period systems have been measured, there are no periods measured above 30d. As part of a large programme to characterize the orbital periods of sdB binaries and their formation history, we have found that PG 1018-047 has an orbital period of 759.8+/-5.8d, easily making it the longest period ever detected for a sdB binary. Exploiting the Balmer lines of the subdwarf primary and the narrow absorption lines of the companion present in the spectra, we derive the radial velocity amplitudes of both stars, and estimate the mass ratio M_MS_/M_sdB_=1.6+/-0.2. From the combination of visual and infrared photometry, the spectral type of the companion star is determined to be mid-K.2012MNRAS.421.2798Dhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/421/2798CatalogResearchIsServedByTAP VizieR generic servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/421/2798https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/421/2798http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/421/2798https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/421/2798https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/421/2798http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/421/2798GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/MNRAS/421/2798/table1Journal of observationsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintDateObservation date(s)time.epoch;obscharSetupSetupinstr.setupcharRegionlambda regionmeta.notecharNspNumber of spectrameta.numberintDispMean dispersion ({AA}/pix)0.1nm/pixinstr.dispersion;stat.meanfloatObsObserver(s) (1)obs.observercharJ/MNRAS/421/2798/table3The 125 RV measurements for PG 1018-047 with their formal errors from the least-squares fitting routinerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHJDHeliocentric Julian date (HJD-2450000)dtime.epochdoublef_RV[abcd] Note on the data points (1)meta.codecharRVRadial velocitykm/sphys.veloc;pos.heliocentricfloate_RVrms uncertainty on RVkm/sstat.errorfloatJ/MNRAS/421/2798/tablea1RV measurements for PG 1018-047 with error and offset correction, as used for the final orbital fit resultsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSetupSetup (1)instr.setupcharHJDHeliocentric Julian date (HJD-2450000)dtime.epochdoubleRVRadial velocitykm/sphys.veloc;pos.heliocentricfloate_RVrms uncertainty on RVkm/sstat.errorfloat