J/A+A/702/A11ivo://CDS.VizieR/J/A+A/702/A11doi:10.26093/cds/vizier/bc-ny/lbbCDSGuo Y.Chen K.Li Z.Ju J.Liu C.Xue X.Dorsch M.Han Z.Chen X.2026-08-28T12:32:17Z2025-09-26T10:44:41ZCDS support team

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

cds-question@unistra.frspectroscopic-binary-starshorizontal-branch-starsradial-velocityvisible-astronomyBlue horizontal branch (BHB) stars are old, low-mass, metal-poor stars that serve as important tracers of the Galactic halo structure, kinematics, and evolution. Understanding their binary properties provides key insights into their formation channels and the role of binary interactions in the evolution of horizontal branch stars. We investigated the intrinsic binary fraction fbin of BHB stars and its dependences on metallicity, kinematics, and effective temperature. We collected 299 BHB stars from LAMOST with multiple radial velocity (RV) measurements and classified the sample into halo-like and disk-like BHBs based on their kinematics and metallicity, and into bluer and redder BHBs based on their effective temperature. We then investigated the observed binary fraction for each group based on the radial velocity variations and applied a set of Monte Carlo simulations, assuming distributions of f(P){prop.to}P^pi^ and f(q){prop.to}q^kappa^, to correct the observed binary fraction for observational biases and to derive the intrinsic binary fraction. The observed binary fraction of BHB stars is 18%+/-2% for cases with n>=2 and 21%+/-3% for cases with n>=3, where n represents the number of observation times. After correcting for observational biases, the intrinsic binary fraction increases to 31%+/-3% for n>=2 and 32%+/-3% for n>=3. A clear contrast is observed between halo-like and disk-like BHB stars, with halo-like BHBs exhibiting a lower intrinsic binary fraction (28%+/-3% for n>=2 and 29%+/-3% for n>=3) compared to disk-like BHBs (46%+/-11% and 51%+/-11%, respectively), indicating different formation pathways. In particular, halo-like BHB stars are more likely to have formed via a single-star evolution channel, whereas disk-like BHB stars may predominantly result from binary evolution processes. Additionally, we find that bluer BHB stars exhibit a significantly higher binary fraction (42%+/-6% for n>=2 and 45%+/-6% for n>=3) than redder BHB stars (24%+/-5% and 23%+/-5%, respectively), which suggests a possible link between binarity and the effective temperature, although more samples are required to confirm this. No correlation is found between {pi} ({kappa}) and metallicity or kinematics, nor between {pi} ({kappa}) and the effective temperature of BHB stars.2025A&A...702A..11Ghttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/702/A11CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/702/A11https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/702/A11http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/702/A11https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/702/A11https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/702/A11http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/702/A11GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/702/A11/table1 (The radial velocity catalog)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/702/A11/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/702/A11/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/702/A11/table1?GETtext/xml+votable180.050000true0.594894.922760.0055555555555555566/453 466-467 504 687 700 750 2305 2316 2333 2619 2626 2656 2720 4112 4136 4245 4272 4319 4334-4335 4343 4517 4589 4604 4666 4696-4697 4714 4797 4805 4880 4921 4949 4965 4967 4984 4987 4991 5020 5073 5142 5145-5146 5187 5190 5193 5198 5363 5437 5453 5472 5647 5655 5693 5712 5755 5776 5783 5793 5796 5837 5894 5898 5928 5949 5988 6050 6085 6167 6198 6245 6375 6442 6493 6586 6621 6773 6923-6924 6963 7108 7297 7336 7364 8207 8262 8280-8282 8305 8354 8374 8534 8692 8703 8814 8849 8856 8868 8873 8893 8899 8956 8965 8977 8988 8998 9013 9019 9066 9078 9080 9100 9105 9129 9132 9204 9207 9209 9215 9243 9248 9250 9279 9283 9373 9474 9482 9485 9504 9685 9687 9736 9753 9768-9769 9785-9786 9838-9839 9842 9852 9858 9873 9921 9926 9958 9982 9988 10032 10095 10264 10282 10327 10360 10371 10388 10402 10422 10465 10488 10607 10638 10702 10706 10754-10755 10811 10882 10885 10888 10897 11002 11036 11060 11069 11106 11123 11153 11285 11333 11366 11370-11371 11489 12355 12358 12366 12609 12613 12679 12690 13396 13441 13576-13577 14983 17856 17861 17864 18034 18304 18315 19061 19155 19159 19316 19333 19341 19437 19482 19511 19590 19620 19801 20142 20185 20335 20375 20426 20435 20441 21858 21887 21976 22364 22777 22783 22806 23298 23350-23351 23522 25815 26008-26009 26015 26019 26031 26042 26294 26340 26379 26416 26621 26993 27076 27089 27097 27122 27172 27334 27507 27524 27590 27655 27771 27816 28007 28027 28112 28138 28150 28245-28246 28376 28384 28401 28421 28571 28575 28623 28627 31657 31915 31976 32269 32291-32292 32441 32460 32502 32544 32547 32549-32550 32640 32659 32763https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/702/A11?format=asciiOpticaldefaultJ/A+A/702/A11/table1The radial velocity catalogrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000Right Ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Declination (J2000)degpos.eq.dec;meta.mainMJDModified Julian Date of the observationdtime.epochdoublesnrSignal-to-noise ratio of the spectrumstat.snrfloatTeffEffective temperatureKphys.temperature.effectivedoubleloggSurface gravitylog(cm.s**-2)phys.gravitydouble[Fe/H]Metallicity [Fe/H]phys.abund.ZdoubleRVRadial velocitykm/sphys.veloc;pos.heliocentricfloate_RVUncertainty in radial velocitykm/sstat.errorfloatSimbadNameSimbad column added by the CDSmeta.idcharnullable