J/A+A/642/A180ivo://CDS.VizieR/J/A+A/642/A180doi:10.26093/cds/vizier.36420180CDSPelisoli I.Vos J.Geier S.Schaffenroth V.Baran A.S.2024-07-16T20:01:36Z2021-02-10T13:56:40ZCDS support team

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

cds-question@unistra.frmultiple-starssubdwarf-starsHot subdwarfs are core-helium burning stars that show lower masses and higher temperatures than canonical horizontal branch stars. They are believed to be formed when a red giant suffers an extreme mass-loss episode. Binary interaction is suggested to be the main formation channel, but the high fraction of apparently single hot subdwarfs (up to 30%) has prompted single star formation scenarios to be proposed. We investigate the possibility that hot subdwarfs could form without interaction by studying wide binary systems. If single formation scenarios were possible, there should be hot subdwarfs in wide binaries that have undergone no interaction. Angular momentum accretion during interaction is predicted to cause the hot subdwarf companion to spin up to the critical velocity. The effect of this should still be observable given the timescales of the hot subdwarf phase. To study the rotation rates of companions, we have analysed light curves from the Transiting Exoplanet Survey Satellite for all known hot subdwarfs showing composite spectral energy distributions indicating the presence of a main sequence wide binary companion. If formation without interaction were possible, that would also imply the existence of hot subdwarfs in very wide binaries that are not predicted to interact. To identify such systems, we have searched for common proper motion companions with projected orbital distances of up to 0.1pc to all known spectroscopically confirmed hot subdwarfs using Gaia DR2 astrometry. We find that the companions in composite hot subdwarfs show short rotation periods when compared to field main sequence stars. They display a triangular-shaped distribution with a peak around 2.5 days, similar to what is observed for young open clusters. We also report a shortage of hot subdwarfs with candidate common proper motion companions. We identify only 16 candidates after probing 2938 hot subdwarfs with good astrometry. Out of those, at least six seem to be hierarchical triple systems, in which the hot subdwarf is part of an inner binary. The observed distribution of rotation rates for the companions in known wide hot subdwarf binaries provides evidence of previous interaction causing spin-up. Additionally, there is a shortage of hot subdwarfs in common proper motion pairs, considering the frequency of such systems among progenitors. These results suggest that binary interaction is always required for the formation of hot subdwarfs.2020A&A...642A.180Phttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/642/A180CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/345 : Gaia DR2 (Gaia Collaboration, 2018)J/A+A/635/A193 : Catalogue of hot subdwarf stars DR2 (Geier, 2020)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/642/A180https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/642/A180http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/642/A180https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/642/A180https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/642/A180http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/642/A180GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/642/A180/table1 (61 variables in our whose variability was attributed to rotation of the main sequence companion, identified by their TESS Input Catalogue (TIC) numbers)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/642/A180/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/642/A180/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/642/A180/table1?GETtext/xml+votable180.050000true13.0627889-10.66279310.005555555555555556Cone search capability for table J/A+A/642/A180/table2 (27 objects whose cause for variability is undetermined)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/642/A180/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/642/A180/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/642/A180/table2?GETtext/xml+votable180.050000true75.8935997-28.45478970.005555555555555556Cone search capability for table J/A+A/642/A180/table3 (Systems for which no periodic variability has been detected)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/642/A180/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/642/A180/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/642/A180/table3?GETtext/xml+votable180.050000true350.7838067-18.26260670.005555555555555556Cone search capability for table J/A+A/642/A180/table4 (Identified common proper motion candidates)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/642/A180/table4?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/642/A180/table4?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/642/A180/table4?GETtext/xml+votable180.050000true15.305573931.43207970.0055555555555555566/502 638 762 2180 2221 4271 6333 6991 7052 7925 8100 9465 10159 11375 11479 11518 11549 11639 11682 11793 11795 11815 11901 12093 12097 13385 13437 14231 14949 15301 16564 16588 16621 16674 16896 17006 17159 17162 17570 17636 17774 19801 20657 21133 21150 21218 21830 22531 22579 23173 23429 23508 24025 24720 24757 24774 25123 25234 25250 25324 26652 26685 26889 27486 31912 32780 32785 32790 32817 32899 32911 32947 33009-33010 33484 33564 33855 34094 34518 34655 34804 34871 35072 35486 35707 36085 36429 36490 36726 37376 37486 38369 38702 38804 38876 40407 40428 43646 44612 45122 45155 45288 45330 45340 45390 45418 45534 45775 45816 45965 46387 46634 46714 46757 46798 46849 46873 46878 46916 47101 47105 47184 47212 47216 47225 47501 48144 48156 48161 48171 48213 48260 48310 48438 484811.9867573869263685e-19 3.916500758235022e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/642/A180?format=asciidefaultJ/A+A/642/A180/table161 variables in our whose variability was attributed to rotation of the main sequence companion, identified by their TESS Input Catalogue (TIC) numbersSimbadSimbad column added by the CDSmeta.ref.urlcharTICTIC identification numbermeta.id;meta.mainlongrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGmagGaia DR2 G magnitudemagphot.mag;em.optfloatCROWDSAPOptimal aperture (CROWDSAP) (G1)stat.fit.paramfloatPerPeriod (1)dtime.perioddoublee_Perrms uncertainty on Per (1)dstat.errordoubleAmpAmplitude of variation (1)%src.var.amplitudefloate_Amprms uncertainty on Amp (1)%stat.errorfloatFAPFalse Alarm Probability (2)stat.fit.goodnessdoubleTeffMain sequence companion effective temperature (G2)Kphys.temperature.effective;meta.maininte_Teffrms uncertainty on Teff (G2)Kstat.error;phys.temperature.effectiveintRMain sequence companion radius (G2)solRadphys.size.radius;meta.mainfloate_Rrms uncertainty on R (G2)solRadstat.errorfloat_RAPositions from TESS or Gaia DR2 (right ascension part)degpos.eq.ra;meta.main_DEPositions from TESS or Gaia DR2 (declination part)degpos.eq.dec;meta.mainJ/A+A/642/A180/table227 objects whose cause for variability is undeterminedSimbadSimbad column added by the CDSmeta.ref.urlcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintTICTIC identification numbermeta.id;meta.mainlongGmagGaia DR2 G magnitudemagphot.mag;em.optfloatCROWDSAPOptimal aperture (CROWDSAP) (G1)stat.fit.paramfloatPerPeriod (1)dtime.perioddoublee_Perrms uncertainty on Per (1)dstat.errordoubleAmpAmplitude of variation (1)%src.var.amplitudefloate_Amprms uncertainty on Amp (1)%stat.errorfloatFAPFalse Alarm Probability (2)stat.fit.goodnessdoubleTeffMain sequence companion effective temperature (G2)Kphys.temperature.effective;meta.maininte_Teffrms uncertainty on Teff (G2)Kstat.error;phys.temperature.effectiveintRMain sequence companion radius (G2)solRadphys.size.radius;meta.mainfloate_Rrms uncertainty on R (G2)solRadstat.errorfloat_RAPositions from TESS or Gaia DR2 (right ascension part)degpos.eq.ra;meta.main_DEPositions from TESS or Gaia DR2 (declination part)degpos.eq.dec;meta.mainJ/A+A/642/A180/table3Systems for which no periodic variability has been detectedSimbadSimbad column added by the CDSmeta.ref.urlcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintTICTIC identification numbermeta.id;meta.mainlongGmagGaia DR2 G magnitudemagphot.mag;em.optfloatCROWDSAPOptimal aperture (CROWDSAP) (G1)stat.fit.paramfloatDetLimDetection limit (1)%instr.sensitivityfloatTeffMain sequence companion effective temperature (G2)Kphys.temperature.effective;meta.maininte_Teffrms uncertainty on Teff (G2)Kstat.error;phys.temperature.effectiveintRMain sequence companion radius (G2)solRadphys.size.radius;meta.mainfloate_Rrms uncertainty on R (G2)solRadstat.errorfloat_RAPositions from TESS or Gaia DR2 (right ascension part)degpos.eq.ra;meta.main_DEPositions from TESS or Gaia DR2 (declination part)degpos.eq.dec;meta.mainJ/A+A/642/A180/table4Identified common proper motion candidatesSimbadSimbad column added by the CDSmeta.ref.urlcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintName1Hot subdwarf Gaia DR2 identification numbermeta.id;meta.mainn_Name1[*] Note on Name1 (1)meta.notecharGmag1Hot subdwarf Gaia DR2 G magnitudemagphot.mag;em.optfloatPlx1Hot subdwarf Gaia DR2 parallaxmagpos.parallax.trigfloatpmRA1Hot subdwarf Gaia DR2 proper motion along RA, pmRA*cosDEmas/yrpos.pm;pos.eq.rafloatpmDE1Hot subdwarf Gaia DR2 proper motion along DEmas/yrpos.pm;pos.eq.decfloatName2Candidate companion Gaia DR2 identification numbermeta.idGmag2Candidate companion Gaia DR2 G magnitudemagphot.mag;em.optfloatPlx2Candidate companion Gaia DR2 parallaxmagpos.parallax.trigfloatpmRA2Candidate companion Gaia DR2 proper motion along RA, pmRA*cosDEmas/yrpos.pm;pos.eq.rafloatpmDE2Candidate companion Gaia DR2 proper motion along DEmas/yrpos.pm;pos.eq.decfloatSepAngular separation of the pairarcsecpos.angDistancefloataProjected orbital separation of the pair, assuming the distance of the hot subdwarfAUpos.angDistanceintDPlxDifference in parallax, in units of standard deviationpos.parallax;arith.difffloatDpmDifference in proper motion, in units of standard deviationpos.pm;arith.difffloat_RAPositions from TESS or Gaia DR2 (right ascension part)degpos.eq.ra;meta.main_DEPositions from TESS or Gaia DR2 (declination part)degpos.eq.dec;meta.main