J/ApJ/900/42ivo://CDS.VizieR/J/ApJ/900/42doi:10.26093/cds/vizier.19000042CDSLiu J.Zheng Z.Soria R.Aceituno J.Zhang H.Lu Y.Wang S.,Hamann W.-R.Oskinova L.M.Ramachandran V.Yuan H.Bai Z.Wang S.,McKee B.J.Wu J.Wang J.Lattanzi M.Belczynski K.Casares J.,Gonzalez Hernandez J.I.Rebolo R.2022-03-21T09:26:37Z2022-01-12T07:44:31ZCDS support team

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

cds-question@unistra.frspectroscopic-binary-starsvisible-astronomyspectroscopyinfrared-astronomyline-intensitiesThe mass, origin, and evolutionary stage of the binary system LB-1 have been intensely debated, following the claim that it hosts an ~70M_{sun}_ black hole, in stark contrast with the expectations for Galactic remnants. We conducted a high-resolution, phase-resolved spectroscopic study of its Paschen lines, using the Calar Alto 3.5m telescope. We find that Pa{beta} and Pa{gamma} (after subtraction of the stellar absorption component) are well fitted with a standard double-peaked disk profile. We measured the velocity shifts of the red and blue peaks at 28 orbital phases: the line center has an orbital motion in perfect antiphase with the secondary, and the radial velocity amplitude ranges from 8 to 13km/s, for different methods of profile modeling. We interpret this curve as proof that the disk traces the orbital motion of the primary, ruling out the circumbinary disk and the hierarchical triple scenarios. The phase-averaged peak-to-peak half-separation (a proxy for the projected rotational velocity of the outer part of the disk) is ~70km/s, larger than the orbital velocity of the secondary and inconsistent with a circumbinary disk. From those results, we infer a primary mass 4-8 times higher than the secondary mass. Moreover, we show that the intensity ratio of the blue and red peaks has a sinusoidal behavior in phase with the secondary, which we attribute to external irradiation of the outer part of the disk. Finally, we discuss our findings in the context of competing scenarios proposed for LB-1. Further astrometric Gaia data will test between alternative solutions.2020ApJ...900...42Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/900/42CatalogResearchIsServedByTAP VizieR generic servicerelated-toB/vsx : AAVSO International Variable Star Index VSX (Watson+, 2006-2014)VI/39 : Model Atmospheres (Kurucz, 1979)I/345 : Gaia DR2 (Gaia Collaboration, 2018)J/A+A/530/A115 : Rotating massive MS stars evolutionary models (Brott+, 2011)J/A+A/537/A146 : Stellar models with rotation. 0.8<M<120 (Ekstrom+, 2012)J/A+A/545/A121 : {omicron} Puppis spectra (Koubsky+, 2012)J/A+A/587/A61 : Stellar-mass BH in X-ray transients (Corral-Santana+, 2016)J/A+A/615/A78 : Spectral models for binary products (Goetberg+, 2018)J/A+A/619/A148 : Hot stars observed by XMM-Newton. II. (Naze+, 2018)J/A+A/639/L6 : HERMES spectra of LS V +22 25 (Shenar+, 2020)J/A+A/649/A167 : Hubble spectroscopy of LB-1 (LS V +22 25) (Lennon+, 2021)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/900/42https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/900/42http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/900/42https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/900/42https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/900/42http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/900/42GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticalInfrareddefaultJ/ApJ/900/42/table1Log of our Calar Alto observationsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintDateObservation datetime.epoch;obsnullableBJD[58757.6/58906.4] Barycentric modified Julian Date of mid exposure; BJD-2400000.5dtime.epochdoubleExp[396/1801] Exposure timestime.duration;obs.exposureintPhasePhase at mid exposure (1)time.phasefloatBandObservational band used ("VIS" or "NIR")instr.bandpasscharJ/ApJ/900/42/fig3Asymmetry between the red- and blue-side emission as a function of binary phase, for both Pa{beta} and Pa{gamma}recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBJDBarycentric Julian Date; BJD-2400000dtime.epochdoublePhaseOrbital phasetime.phasefloatR/B-PaBPa{beta} red and blue peak flux differencephot.flux;arith.difffloate_R/B-PaBUncertainty in R/B-PaBstat.errorfloatR/B-PagPa{gamma} red and blue peak flux differencephot.flux;arith.difffloate_R/B-PagUncertainty in R/B-Pagstat.errorfloatEWPaB[-2.3/1.8] Pa{beta} equivalent widths difference (1)0.1nmspect.line.eqWidth;arith.difffloate_EWPaB[0.02/0.3] Uncertainty in EWPaB (1)0.1nmstat.errorfloatEWPag[-1.1/0.8] Pa{gamma} equivalent widths difference (1)0.1nmspect.line.eqWidth;arith.difffloate_EWPag[0.003/0.14] Uncertainty in EWPag (1)0.1nmstat.errorfloatJ/ApJ/900/42/fig5Measurements and model fitting of the projected radial velocities of the secondary star and primaryrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBJDBarycentric Julian Date; BJD-2400000dtime.epochdoublePhaseOrbital phasetime.phasedoubleV2[-24.08/81] Secondary velocitykm/sphys.velocdoubleV1dgb[18.16/37.3] Local Gaussian fit of Pa{beta} mean red & blue peak velocitykm/sphys.velocfloate_V1dgb[0.4/3.8] Uncertainty in V1d-gbkm/sstat.errorfloatVrgbLocal Gaussian fit of Pa{beta} half separation between the red and blue peak velocitykm/sphys.velocfloate_VrgbUncertainty in Vr-gbkm/sstat.errorfloatV1dgg[15.3/38.4] Local Gaussian fit of Pa{gamma} mean red & blue peak velocitykm/sphys.velocfloate_V1dgg[0.38/4.7] Uncertainty in V1d-ggkm/sstat.errorfloatVrggLocal Gaussian fit of Pa{gamma} half separation between the red and blue peak velocitykm/sphys.velocfloate_VrggUncertainty in Vr-ggkm/sstat.errorfloatV1dsbExtended Smak Fit of Pa{beta} mean red & blue peak velocitykm/sphys.velocfloate_V1dsbUncertainty in V1d-sbkm/sstat.errorfloatVrsbExtended Smak Fit of Pa{beta} half separation between the red and blue peak velocitykm/sphys.velocfloate_VrsbUncertainty in Vr-sbkm/sstat.errorfloatV1dsgExtended Smak Fit of Pa{gamma} mean red & blue peak velocitykm/sphys.velocfloate_V1dsgUncertainty in V1d-sgkm/sstat.errorfloatVrsgExtended Smak Fit of Pa{gamma} half separation between the red and blue peak velocitykm/sphys.velocfloate_VrsgUncertainty in Vr-sgkm/sstat.errorfloat