arXiv:astro-ph/0107375v1

19Jul2001Astronomy&Astrophysicsmanuscriptno.
(willbeinsertedbyhandlater)MassratiosofthecomponentsinTTauribinarysystemsandimplicationsformultiplestarformationJ.
Woitas1,2,Ch.
Leinert2,andR.
K¨ohler3,21Th¨uringerLandessternwarteTautenburg,Sternwarte5,07778Tautenburg,Germany2Max-Planck-Institutf¨urAstronomie,K¨onigstuhl17,69117Heidelberg,Germany3CenterforAstrophysicsandSpaceSciences,UniversityofCalifornia,SanDiego,9500GilmanDrive,LaJolla,CA92093-0424,USAReceived/AcceptedAbstract.
Usingnear-infraredspeckleinterferometrywehaveobtainedresolvedJHK-photometryforthecomponentsof58youngbinarysystems.
Fromthesemeasurements,combinedwithotherdatatakenfromliterature,wederivemassesandparticularlymassratiosofthecomponents.
WeusetheJ-magnitudeasanindicatorforthestellarluminosityandassigntheopticalspectraltypeofthesystemtotheprimary.
OntheassumptionthatthecomponentswithinabinaryarecoevalwecanthenplacealsothesecondariesintotheHRDandderivemassesandmassratiosforbothcomponentsbycomparisonwithdierentsetsofcurrenttheoreticalpre-mainsequenceevolutionarytracks.
TheresultingdistributionofmassratiosiscomparativelyatforM2/M1≥0.
2,butdependsonassumedevolutionarytracks.
Themassratioisneithercorrelatedwiththeprimary'smassorthecomponents'separation.
ThesendingsareinlinewiththeassumptionthatformostmultiplesystemsinTassociationsthecomponents'massesareprincipallydeterminedbyfragmentationduringformationandnotbythefollowingaccretionprocesses.
Onlyveryfewunusuallyredobjectswerenewlyfoundamongthedetectedcompanions.
ThisndingshowsthattheobservedoverabundanceofbinariesintheTaurus-Aurigaassociationcomparedtonearbymainsequencestarsshouldberealandnottheoutcomeofobservationalbiasesrelatedtoinfraredobserving.
Keywords.
binaries:general–stars:pre-mainsequence–stars:formation–stars:fundamentalparameters–techniques:interferometric–infrared:stars1.
IntroductionMoststarsinthesolarneighbourhoodaremembersofmultiplesystems(e.
g.
Duquennoy&Mayor1991,Fischer&Marcy1992).
Thisraisesthequestionwhethermostofthesesystemswereformedasbinariesorwhethertheyaretheresultoflatercaptureprocesses.
Afterhighangu-larresolutiontechniquesinthenearinfrared(NIR)hadbeendevelopedatthebeginningofthe1990sthisproblembecameanissueofobservationalastronomy.
Alargenumberofmultiplicitysurveysinstarformingre-gions(SFRs)andclustershasnowbeendone(seeMathieuetal.
2000andreferencestherein).
Itisstillamatterofdebateifdierentenvironmentalconditionsofstarforma-tionleadtodierentdegreesofmultiplicity.
Onecanhow-Sendoprintrequeststo:JensWoitas,e-mail:woitas@tls-tautenburg.
deBasedonobservationscollectedattheGerman-SpanishAstronomicalCenteronCalarAlto,Spain,andattheEuropeanSouthernObservatory,LaSilla,Chile.
everconcludethatthereisatthistimenosampleofyoungstarsthatshowsasignicantbinarydecitcomparedtonearbymainsequencestars.
InsomeSFRsevenastrongbinaryexcessisobserved.
Theconsequenceofthesere-sultsisthatmultiplicitymustbealreadyestablishedinveryearlyphasesofstellarevolutionandthatstarforma-tiontoalargeextenthastobeconsideredasformationofmultiplestars.
Multiplicityhastobetakenintoaccountifoneasksforstellarproperties.
Ifthisquestionisaddressedtothesystemsinsteadofthecomponents,misleadingre-sultsmaybeobtained.
InthispaperwewilldiscussyoungbinarysystemsinthenearbySFRsTaurus-Auriga,UpperScorpius,ChamaeleonIandLupusthathavebeendetectedbyLeinertetal.
(1993),Ghezetal.
(1997a)andK¨ohleretal.
(2000).
Wepresentresolvedphotometryofthecompo-nentsintheNIRspectralbandsJ,HandK(Sect.
2).
Basedonthesedatawediscussthecomponentsinacolor-colordiagram(Sect.
3)andinacolor-magnitudedi-agram(Sect.
4).
UsingtheJ-bandmagnitudeasindica-2J.
Woitasetal.
:MassratiosofTTauristarcomponentstorforthestellarluminosityandpulishedspectraltypesfortheprimaries,weplacethecomponentspairwiseintotheHertzsprung-Russelldiagram(HRD,Sect.
5)andde-rivemassesandinparticularmassratiosfromacompar-isonwiththeoreticalPMSevolutionarymodels(Sect.
6).
Implicationsoftheresultsfortheoreticalconceptsofmul-tiplestarformationandforbinarystatisticsarediscussedinSect.
7.
2.
Observationaldata2.
1.
SystempropertiesIfnotstatedotherwisewetakethesystems'magni-tudes,interstellarextinctioncoecientsAVandspectraltypesfromtheliterature.
ThereferencesareKenyon&Hartmann(1995)forTaurus-Auriga,Walteretal.
(1994)andalsoK¨ohleretal.
(2000)forUpperScorpius,Gauvin&Strom(1992)forChamaeleonIandHughesetal.
(1994)forLupus.
PossibleeectsofvariabilityarediscussedinSect.
4.
2.
2.
2.
2.
SpatiallyresolvedphotometryDatafortheobjectsinTaurus-Aurigawereobtaineddur-ingseveralobservingrunswiththeNIRcameraMAGICatthe3.
5m-telescopeonCalarAltofrom1993to1998.
MeasurementsatthistelescopebeforeSeptember1993weredonewithadeviceforone-dimensionalspeckle-interferometrythathasbeendescribedbyLeinert&Haas(1989).
ObservationsofmultiplesystemsinsouthernSFRswerecarriedoutinMay1998attheESONewTechnologyTelescope(NTT)onLaSillathatisalsoa3.
5m-telescope,usingtheSHARPcameraoftheMax-PlanckInstituteforExtraterrestrialPhysics(Hofmannetal.
1992).
Sincemostbinariesofoursamplehaveprojectedsepara-tionsoflessthan1′′ahighangularresolutiontechniqueisneededtoovercometheeectsofatmosphericturbulenceandtoreachthediractionlimitwhichisλ/D=0.
′′13fora3.
5m-telescopeatλ=2.
2m.
Wehavemostlyusedtwo-dimensionalspeckleinterferometry.
Sequencesoftyp-ically1000imageswithexposuretimesof≈0.
1secweretakenfortheobjectandanearbyreferencestar.
Afterbackgroundsubtraction,ateldingandbadpixelcorrec-tionthesedatacubesareFourier-transformed.
Wedeterminethemodulusofthecomplexvisibility(i.
e.
theFouriertransformoftheobjectbrightnessdistribu-tion)frompowerspectrumanalysis.
Thephaseisre-cursivelyreconstructedusingtwodierentmethods:TheKnox-Thompsonalgorithm(Knox&Thompson1974)andthebispectrumanalysis(Lohmannetal.
1983).
AdetaileddescriptionofthisdatareductionprocesshasbeengivenbyK¨ohleretal.
(2000,AppendixA).
Modulusandphaseshowcharacteristicstrippatternsforabinary.
Inthecaseofatripleorquadruplestarthesepatternswillbeover-layedbysimilarstructuresthatbelongtotheadditionalcompanion(s).
Fittingabinarymodeltothecomplexvisibilityyieldsthebinaryparameterspositionangle,projectedsepara-tionanduxratio.
Theerrorsoftheseparametersarees-timatedbydoingthistfordierentsubsetsofthedata.
Thecomparisonofourpositionanglesandprojectedsepa-rationswiththoseobtainedbyotherauthorsthathasbeendoneinanotherpaper(Woitasetal.
2001)hasshownthatsystematicdierencesinrelativeastrometryarenegligi-ble.
DierencesinresolvedK-bandphotometryhaveanorderofmagnitudethatcanbeexplainedbythevariabil-ityofTTauristars.
Togetherwiththesystembrightnessthatistakenfromtheliteratureinmostcasestheuxratiodeterminesthecomponents'magnitudes.
Wepresenttheresultsofourin-dividualmeasurementsinTableA.
1.
ToreducetheeectofthevariabilityofTTauristarswecalculatethemeanofallresolvedphotometricobservationsinonelterob-tainedbyusandotherauthors(seecaptionofTableA.
2forreferences).
2.
3.
PotentialofthedatasetOursamplegrewoutofsurveysformultiplicityinstarformingregions.
Withatotalof119individualcompo-nentsitisofreasonablesize.
Byconstructionitislargelyindependentofbiasesduetoduplicity.
Thismakesitwellsuitedforstatisticaldiscussions.
Fromtheresolvedphotometryalonewecancheckforcir-cumstellarexcessemission,searchforpossibleinfraredcompanions,detectcontaminationbybackgroundstarsandhavesomecheckonwhetherthecomponentsofabi-narysystemarecoeval.
Inthelastpointweencounterthelimitationsofourmethod:thelargeuncertaintyincolor,resultingmainlyfromvariability,seriouslydegradespos-sibleagedeterminations.
ThereforeweuseintheHRDknownspectraltypestoderivemassesforthecomponentsdominatingthevisualregion,andderivedmassesforthecompanionsontheas-sumptionofcoevality.
Thereliabilityofthesemassdeter-minationprotsfromourexplicitknowledgeofduplicity.
Thepresentationoftheresultsstartswiththoseresultingfromresolvedphotometryalone.
3.
Color-colordiagram3.
1.
PresenceofcircumstellarexcessemissionWecorrecttheresolvedJHK-photometryforinterstellarextinctionusingthereddeninglawofRieke&Lebovsky(1985)andapplyingtheAVgiveninTableA.
2toallcom-ponentsofonesystem.
Theresultingdereddenedcolorsarenotnecessarilystel-larcolors,becauseinfraredexcessemissioncausedbycir-cumstellardisksisacommonphenomenoninTTauristars(e.
g.
Beckwithetal.
1990).
Forthisreasonwerstconsiderasubsampleofsystemsthatconsistofweak-linedTTauristars(WTTS).
Theadoptedclassicationcrite-rionforWTTSisthattheirHαequivalentwidthislessthan10A(Herbig&Bell1988).
WTTSarenotexpectedJ.
Woitasetal.
:MassratiosofTTauristarcomponents3Fig.
1.
Color-colordiagramforthecomponentsofweak-linedTTauristars(WTTS,leftpanel)andclassicalTTauristars(CTTS,rightpanel).
Thealmostverticalsolidlinedenotesthemainsequence,withthegiantbranchtotheright(Bessell&Brett1988).
Thedottedlinesareparalleltothereddeningvector(indicatedforAV=5inthelowerrightofbothpanels).
Thecrossgivesthetypicalerrorbarsofourobservations(seeSect.
4.
2).
Onlyintheregionlabeled'A'andonthemainsequencetheobservedcolorsareconsistentwithphotosphericemission,whereasforobjectslocatedrighttothisregioncircumstellarexcessemissionispresent.
ThenumbersintherightpaneldenoteHaro6-28B(1),CZTauB(2),theinfraredcompanionofXZTau(3),thecomponentsofFSTau(4,5),HNTauA(6)andtheinfraredcompanionofUYAur(7).
tohaveprominentdisksandtheirmeanexcessemissioninJ,HandKiszero(Hartiganetal.
1995).
Almostallcom-ponentsofthesesystemshavecolorscomparabletomainsequencestars(Fig.
1,leftpanel)asisexpected.
TheonlyexceptionsarethetwocomponentsofUXTauBandthecompanionofV773Tau.
ForcomponentsofsystemswithclassicalTTauristars(CTTS)wheresignicantcircum-stellarexcessemissionisexpected,thepositionsinthecolor-colordiagramaremuchmorespreadaround(Fig.
1,rightpanel).
Thesecolorscannotbereferredtostellarphotospheresinasimpleway.
3.
2.
InfraredcompanioncandidatesItisinterestingtolookforcompanionswithextremeredcolors,becausethesecanbecandidatesforinfraredcom-panions(IRCs).
IRCsareobjectsthatareveryweakorhaveevennotbeendetectedatopticalwavelengths,butdominatethesystem'sbrightnessintheinfrared.
Theyaresomewhatpuzzlingforstarformationtheory,becausesomeofthemappeartobemoremassivethantheoptical"primary"butareatthesametimemoreembeddedandlessevolved.
Atthistime8IRCsareknown(Koreskoetal.
1997,Ressler&Barsony2001).
Twooftheseobjects–XZTauBandUYAurB–doindeedshowunusualredcolorsinthecolor-colordiagram(Fig.
1,rightpanel).
TwootherknownIRCsthatbelongtooursample–TTauBandHaro6-10B–arenotdiscussedhere,becausewecouldnotdetectthoseobjectsintheJ-band.
InFig.
1wehavealsoindi-catedCZTauB,Haro6-28B,bothcomponentsofFSTauandHNTauAasunsuallyredobjects.
Forthesesystemsadditionalspatiallyresolvedobservationsatlongerandshorterwavelengthswillbenecessarytodecideiftheyre-allycontainIRCs.
ThebestcandidateforanewIRCisthecompanionofFVTau/cthatwehaveobservedinHandK,butfailedtodetectintheJ-band.
Ghezetal.
(1997a)haveproposedHBC603BandVWChaCtobeIRCs,becausetheseob-jectswerefoundbytheirK-bandsurvey,butmissedatλ=0.
9mbyReipurth&Zinnecker(1993).
Wehaveob-servedthesesystemsinJandHanddidnotdetectanycompanioneither,whichcallsforadditionalobservationsatlongerwavelengths.
Extinctionbycircumstellarenvelopesoredge-ondisksisnottheonlypossibleexplanationforextremelyredcolors.
Theobjectsmentionedinthissectionmayalsohaveaverylatespectraltypeandmayevenbeyoungbrowndwarfs.
WewilldiscussthetopicofpossiblesubstellarcompanionsinSect.
6.
1.
InanycaseextremelyredobjectsarenotfrequentamongthecompanionsdetectedbyLeinertetal.
1993inTaurus-4J.
Woitasetal.
:MassratiosofTTauristarcomponentsAuriga.
ThisindicatesthattheobservedoverabundanceofbinariesinthisSFRcomparedtonearbymainsequencestarsisrealandnottheresultofusinginfraredwave-lengthsformultiplicitysurveysamongyoungstars.
4.
Color-magnitudediagram4.
1.
ConversionofPMSmodelsintotheobservationalplaneForcomparisonwiththedata,weconvertluminosityLandTefordistinctmassesandagesfromthetheoreti-calatmospheremodelstonear-infraredcolorsandmagni-tudes.
TothispurposeweuserelationshipsthatgivethebolometriccorrectionBCVandseveralcolorsasafunctionofspectraltypeorthecorrespondingTe.
TheserelationsaretabulatedbyBessell(1991),Bessell&Brett(1988)andSchmidt-Kaler(1982).
Tointerpolatebetweenthedata-pointsgiveninthesetablesweusepolynomialtsthathavebeendonebyMeyer(1996).
TheapparentJ-bandmagnitudeisderivedfromLandTeusingthefollowingequation:J=4.
742.
5logLL⊙BCV(Te)(VJ)Teff(1)+(mM)0.
282AV.
ThecoecientbeforeAVistakenfromtheinter-stellarreddeninglawofRieke&Lebovsky(1985).
FortheH-andK-bandmagnitudestherearesimilarrelations.
4.
2.
ErrorsofcolorsandmagnitudesThemagnitudeerrorsthataregiveninTableA.
2aretheerrorsofthemeanmagnitudethatresultfromaveragingoverallspatiallyresolvedmeasurementsinagivenspectralband.
Ifonlyoneobservationhasbeendonetheerroriscalculatedfromtheuncertaintiesofmeasuredsystemphotometryanduxratio,asgiveninTableA.
1.
ForthecomparisonofcolorsandmagnitudestotheoreticalPMSmodelsadditionalerrorsourceshavetobetakenintoaccount.
4.
2.
1.
DistanceToobtainthedistancemodulusmMusedinEq.
1weadoptdistancestotheSFRsthatarethemeanofallHipparcosdistancesderivedformembersoftherespectiveassociation.
ThevaluesandreferencesaregiveninTable1.
However,distancestoindividualobjectsmaybedierentfromthesemeanvalues.
TotakethisintoaccountweassumethattheradialdiametersoftheSFRsareaslargeastheirprojecteddiametersonthesky.
Thelatterquantitycanbeestimatedtobe≈20forTaurus-Auriga(seeFig.
1inK¨ohler&Leinert1998)aswellasforScorpius-Centaurus(seeFig.
1inK¨ohleretal.
2000).
ConcerningthemeandistancesfromTable1Table1.
AdopteddistancestostarsinnearbySFRsSFRdistance[pc]referenceTaurus-Auriga142±14Wichmannetal.
(1998)UpperScorpius145±2deZeeuwetal.
(1999)ChamaeleonI160±17Wichmannetal.
(1998)Lupus190±27Wichmannetal.
(1998)Fig.
2.
Distributionofvariabilityamplitudesforcompo-nentsofyoungbinarysystemsintheNIRspectralbandsJ,HandK.
Theycontainallofthesystemsdiscussedinthispaperforwhichrepeatedspatiallyresolvedobserva-tionsinonelterexist(seeTableA.
1forourobservationsandcaptionofTableA.
2forreferencestootherpublisheddata).
thiscorrespondstoadiameterof50pc.
Weassumehere±25pcasuncertaintyforthedistanceofanindividualsystemwhichisaveryconservativeestimate:morethantwothirdsofthestarswillbewithin±15pcforanevenspatialdistribution.
4.
2.
2.
VariabilityTTauristarsarevariable.
Althoughthiseectismuchlessintheinfraredcomparedtoopticalwavelengths(Nurmanova1983),itcannotbeneglected.
Weusethosecomponentsforwhichthereareobservationsinthesamelteratdierentepochstoestimatetheinuenceofvari-abilityonthemagnitudes.
Thedistributionofvariabil-ityamplitudesisgiveninFig.
2.
ThemeanamplitudesthatweconsiderasvariabilityerrorsareσJ=0.
12mag,σH=0.
07magandσK=0.
09mag.
Thesevariations,asderivedfromourdataset,aresimilartothoseinthetab-ulationofRydgrenetal.
(1984)butsmallerthanthosefoundbySkrutskieetal.
(1996).
Thereforeourestimateofvariabilitymaybesomewhatoptimistic.
J.
Woitasetal.
:MassratiosofTTauristarcomponents54.
2.
3.
DereddeningKenyon&Hartmann(1995)havegivenfortheextinctionanerrorofσ(AV)=0.
3magforthesystemsinTaurus-Auriga.
WeadoptthiserroralsoforthesystemsinotherSFRs.
4.
2.
4.
TheoreticalAtmosphereModelsThefollowingtwoerrorsourcesdonotaectcolorsormagnitudes,butthetransformationoftheoreticalPMSmodelstoobservablequantities.
Bythiswaytheyalsoentertheerrordiscussion:–ForthebolometriccorrectionusedinEq.
1anerrorσ(BCV)=0.
04magisadoptedasgivenbyHartiganetal.
(1994).
–AsalreadymentionedinSect.
4.
1theconversionoflu-minosityandTeintoNIRmagnitudesandcolorsusespolynomialtstotabulateddata.
Thiscausesaner-rorof0.
07maginJ,HandK,exceptforthemodelsofBaraeetal(1998),whichdirectlygiveintegratedmagnitudesoverthenear-infraredbands.
4.
2.
5.
ErrorofcolorsAllmentionederrorsaddedinquadraturegivetheun-certaintyofaNIRmagnitudethathastobeconsideredwhenplacingthecomponentsintoacolor-magnitudedi-agram.
Ifacolorisderivedfromthesemagnitudessomeerrorscancel:Thedistanceisthesameforallcomponentsandvariabilityissupposedtobenegligibleifobservationsatbothwavelenghtsarecarriedoutinthesamenight.
Unfortunatelythisisnotthecaseformostofourobjects.
ToobtainacolorfromTeonedoesnotneedabolometriccorrection,soalsotherespectiveerrorcanbediscarded.
4.
3.
Placingthecomponentsintocolor-magnitudediagramsInFig.
3theplacementofthecomponentsintoaJ/(H-K)color-magnitudediagramsisshown.
ThePMSevolution-arymodelbyD'Antona&Mazzitelli(1998)isalsoindi-catedintheFigure.
ThedistributionofobjectsinaJ/(J-K)colour-magnitudediagramwouldlookquitesimilar.
Almostallcomponentsareabovethelowermainsequenceastheyareexpectedtobe.
Butmanystarslieinare-gionthatisnotcoveredbytheevolutionarytracks.
Thiscannotbecorrectedbyfurtherdereddening,butmustbeduetothepresenceofcircumstellarcolorexcessesthatwehavealreadymentionedabove.
E.
g.
,nearlyallstarsthathaveanunusuallylargeH-KareCTTS(representedbytriangles)andtheonlyWTTSinthisregionarethecom-ponentsofV773TauandUXTauwherewehavenoticedexcessemissionalreadyinSect.
3.
1.
4.
4.
RelativeagesofcomponentsSincethereisnoresolvedspectroscopyofthecomponents,wecannotcorrectforthecolorexcessesmentionedintheprevioussection.
Forthisreasonwerestrictthediscussionofthecomponentsinthecolor-magnitudediagramtoasubsampleof17systemsthatconsistofWTTSwherenosignicantcircumstellarexcessemissionisexpected.
TheplacementoftheindividualcomponentsintoaJ/(J-K)color-magnitudediagramisshowninFig.
4.
Objectbyobject,thepositonsofthecomponentsintheseplotsarecomparedtothePMSevolutionarymodelbyD'Antona&Mazzitelli(1998)tocheckforcoevalityandvalidityoftheassociation.
WehavealsousedthesetsofPMStracksandisochronesgivenbySwensonetal.
(1994)andBaraeetal.
(1998)andhaveobtainedsimilarresults.
WithrespecttotheD'Antona&Mazzitelli(1998)tracksin14outof17casesthecomponentsappeartobeco-eval.
Unfortunately,thisndinghasnotmuchweightbe-causeofthelargeerrorsincolor.
Neverthelesssomeuse-fulcheckscanbeperformed.
ThethreeproblematiccasesareV773Tau,UXTauandV819Tau.
Forthersttwosystemswehavealreadynoticedthepresenceofexcessemission(Sect.
3.
1and4.
3).
Ducheneetal.
(1999b)haveproposedtoreclassifyUXTauasaCTTS,becauseitsHαequivalentwidthis9.
5AandthusabovetheupperlimitforWTTSwithspectraltypeKthatis5AaccordingtoMartn(1998).
ThecompanionofV819Tauliesfarbelowthemainsequenceinthecolor-magnitudediagram.
ThisindicatesthatV819TauBisinfactnotabinarycompan-ion,butachanceprojectedbackgroundstar.
ForHBC352/353Fig.
B.
1yieldsanagerangeofabout2*107-2*108yrwhichisproblematicbecausethisageislargerthantheagespreadfoundfortheTaurusSFR(e.
g.
Kenyon&Hartmann1995).
Also,Martnetal.
(1994)calledintoquestionthattheseareyoungstarsbecausetheydonotshowsignicantLithiumlineabsorption.
Withthementionedexceptions,ourdataarecompati-blewiththeassumptionthatthecomponentsoftheTTauribinariesarecoeveal.
Thereareotherstudiesthatbetterprovethatthisassumptionisvalid:Brandner&Zinnecker(1997)haveobtainedspatiallyresolvedspec-troscopyforthecomponentsofeightyoungbinarysystemsandplacedthemintotheHRD.
Inallcasesthecompo-nentsarecoeval.
ParticularlywellthishasbeenshowninthecaseofthequadruplesystemGGTau(Whiteetal.
1999)fromresolvedspectroscopywiththeHSTFaintObjectSpectrograph.
Belowwewillusetheassumptionofcoevalitytoestimatemassesforthecompanionsandmassratiosforthecomponentsinbinarysystems.
5.
PlacingthecomponentsintotheHRDInthissectionwewillplacethecomponentsofyoungbi-narysystemsintotheHRDandcomparetheirpositionsinthisdiagramwiththeoreticalPMSevolutionarymodelstoderivemassesandmassratios.
Forthispurposeonehastoknowtheirluminositiesandspectraltypes.
Sincethese6J.
Woitasetal.
:MassratiosofTTauristarcomponentsFig.
3.
ComponentsofyoungbinarysystemsplacedintoaNIRcolor-magnitudediagramtogetherwiththetheoreticalPMSmodelbyD'Antona&Mazzitelli(1998).
Thesolidlinesareevolutionarytracksfordierentstellarmasses(0.
9to0.
017M⊙),thedashedlinesareisochronesforagesfrom7*104yrto108yr.
Thelatterageisassignedtothemainsequence(MS).
Thecrossesdenotetypicalerrorbarsforthestars'positions,thearrowsarereddeningvectorsforAV=5mag.
CTTSarerepresentedbytrianglesandWTTSbysquares.
TheWTTSindicatedwithnumbersareV773TauAandB(1,2)andUXTauA,Bandb(3,4,5)quantitiesarenotknownasdirectlymeasuredvalueswehavetomakesomeassumptionstoestimatethemfromourresolvedNIRphotometryandthesystempropertiesthataregivenintheliterature.
5.
1.
LuminositiesAsdescribedinSect.
4.
1forthecolour-magnitudedia-grams,wetransformthetheoreticalatmospheremodelsthatgiveTeandLasfunctionsofmassandageintoadiagraminwhichtheluminosityisrepresentedbyaNIRmagnitude.
Circumstellarexcessemissionisminimalaroundλ≈1m(e.
g.
Kenyon&Hartmann1995).
ForthisreasonweprefertheJ-bandmagnitudesofthecomponentstoHandKasluminosityindicator.
ItishowevernotclearifthisexcessemissionisnegligibleintheJ-band.
Hartiganetal.
(1995)havemeasuredtheveilinginopticalspectraofTTauristars.
AssumingthattheexcessemissionintheJ-bandisrJ=0.
1*rV,whererλ=Fλ,excess/Fλ,,theycometotheconclusionthatforasampleof19CTTSand10WTTSthemeanvalueisconsistentwith=0.
0.
Folha&Emerson(1999)determinedtheNIRexcessemissiondi-rectlyusinginfraredspectraof50TTauristars.
Theirresultisthat=0.
57fortheCTTSintheirsam-pleandthusmuchlargerthanexpected.
Totakethisintoaccountweapplyanexcesscorrectionof0.
49magcorre-spondingtothis,ifweuseJmagnitudesasanindicatorforCTTSstellarluminosities.
FortheWTTSintheirsampleFolha&Emerson(1999)ndvaluesofrJthatarecompatiblewithzero,soforthecomponentsofWTTSsystemsnoexcesscorrectionisnecessary.
5.
2.
SpectraltypesFornearlyallofthesystemsdiscussedhereweknowthecombinedopticalspectraltypefromtheliterature(seeSect.
2.
1andTableA.
2).
WeassumethatthesecombinedJ.
Woitasetal.
:MassratiosofTTauristarcomponents7Fig.
4.
Examplesofcolour-magnitudediagramsfortwoWTTSsystems.
Left:V819Tau,theputativecompanionappearstobeabackgroundobject.
Right:HBC351:anexampleforcoevalityofthecomponents.
ThedataareoverplottedwiththePMSmodelbyD'Antona&Mazzitelli(1998).
Thedashedlinesdenoteevolutionarytracksformassesfrom0.
02to0.
9M⊙,thesolidlinesareisochronesforages7·104,105,2·105,3·105,5·105,7·105,106,2·106,3·106,5·106,7·106,107,2·107,3·107,5·107and108yr(MS).
Thefullgurewithall17colour-magnitude-diagramsisavailableatCDSasFigureB.
1.
Fig.
5.
ThecomponentsoftheyoungbinarysystemIKLupplacedintotheHRDasanexampleforthemethoddescribedinSect.
5.
Thecrossgivesthepositionoftheprimary,thehorizontaldashedlinesthelocusforthesec-ondaryandtherespectiveerror.
ThetheoreticalmodelisbyBaraeetal.
(1998).
Theevolutionarytracksaregivenformassesof0.
04,0.
06,0.
08,0.
10,0.
15,0.
20,0.
25,0.
30,0.
40,0.
50,0.
60,0.
70,0.
80,0.
90,1.
00and1.
20M⊙,theisochronesdenoteagesof1,2,5,10,20,50and90Myr.
Ifthecomponentsarecoevaltheirmasseswillbe0.
9±0.
2M⊙and0.
3±0.
1M⊙.
spectrarepresenttoagoodapproximationthoseoftheopticalprimarycomponents,andweassigntheopticalspectraltypeofthesystemtothebrightestcomponentintheJ-band.
Thespectraltypeandeectivetemperatureofthecompanionisestimatedusingtheassumptionthatallcomponentswithinasystemarecoeval.
WearenowreadytoplacethecomponentsintotheHRD.
TheprocedureisshowninFig.
5usingtheTTauribinarysystemIKLupasanexample.
For48moresystemstheplacementofthecomponentsintotheHRDisshowninFig.
C.
1,availableatCDS.
ThetheoreticalPMSevolutionarymodelusedisbyBaraeetal.
(1998).
ThepositionoftheprimaryisdeterminedbyitsJ-bandmagnitudeandthesystem'sspectraltype.
ForthelatterquantityweassumeanerrorofonespectralsubclassasgivenbyKenyon&Hartmann(1995)forthesystemsinTaurus-Auriga.
Thecompanion'sJ-bandmagnitudeandtherespectiveerrordenealocusforthecompanionintheHRD.
Ifweassumethatbothcomponentsarecoevalthecompanionissituatedatthepointofintersectionbetweenthislocusandtheisochroneoftheprimary.
InthesamewaywealsodenedthelociofthecomponentsintheHRDfortheevolutionarytracksofSwensonetal.
(1994)andD'Antona&Mazzitelli(1998).
6.
MassesandmassratiosTheproceduredescribedintheprevioussectionyieldsthecomponents'masses.
Forinstance,intheIKLupsystem(Fig.
5)thecomponentshavemassesof0.
9M⊙and0.
3M⊙withrespecttotheBaraeetal.
(1998)tracks.
TheresultingmassesderivedforthecomponentsfromallthreesetsofPMStracksusedaregiveninTable2.
Forsomesystems(indicatedwithquestionmarksinTable2)theprimaryislocatedinaregionoftheHRDthatisnotcoveredbytherespectivetracks.
TheSwensonetal.
(1994)modeldoesonlycoveramassrangeabove0.
15M⊙,soforsomesecondariesonlyuppermasslimitscanbederivedfromthatmodel.
TheerrorsgiveninTable2reecttherangeoftracksthatiscoveredbythestars'locationsintheHRD.
Theseuncertaintiesare20-30%formoststarsandthusquitelarge.
However,allerrorsourcesdiscussedsofararerandomandnotsys-8J.
Woitasetal.
:MassratiosofTTauristarcomponentstematic.
ThereforeinastatisticalanalysisofthesemassesthatwewilldoinSects.
6.
2and6.
3,theseuncertaintieswillpartiallycancelandhavelessinuencetotheresults.
TherearehoweveradditionaluncertaintieswithinthePMSmodelstheirselves.
OnecanseefromTable2thattherearediscrepanciesinmassesobtainedforthesamestarsfromdierentPMSmodelsthatcanbemuchlargerthantheindicatederrorswhichtracetheuncertaintyofourmeasurements.
Thecomponents'massfunctionsderivedfromthethreemodels(seeFig.
6)aredierentata99%condencelevelwhichindicatesthatthesemassdierencesaresystematic.
ThereisnowsomeevidencethattheBaraeetal.
(1998)trackscouldbepreferrableamongthecurrentPMSmod-els:Whiteetal.
(1999)haveplacedthefourcomponentsofGGTauintotheHRDandcomparedtheirpositionswithdierentsetsofPMStracks.
TheyfoundthattheBaraeetal.
(1998)modelisbestconsistentwiththeassumptionthatallcomponentsarecoeval.
Simonetal.
(2000)andSteenetal.
(2000)presentedrstresultsofempiricalmassdeterminationsfromorbitalmotionaroundTTauristarsthatarealsocomparablewiththepredictionsoftheBaraeetal.
(1998)model.
ItwouldhoweverbeprematuretoconsidertheseresultsasanalsolutionoftheproblemofinconsistentPMSmodels,mainlybecausethementionedobservationsdonotcoverthewholerangeofmassesandagesexpectedforTTauristars.
Thereforeinthispaperwewill–aswehavealreadydoneinSect.
4.
4–relyonthethreePMSmodelsgivenbyD'Antona&Mazzitelli(1998),Swensonetal.
(1994)andBaraeetal.
(1998)andcomparetherespectiveresults.
Itcanbeseenthattheuncertaintiesinherentintheevolutionarymodelpredictionsoftensurpasstheuncertaintiesresultingfromthemeasurementerrors.
6.
1.
CandidatesforsubstellarcompanionsInsixofoursystemsthemassdeterminationfromtheD'Antona&Mazzitelli(1998)tracksleadstocompanionmassesthatarebelowthehydrogenburningmasslimitofM≈0.
08M⊙(seeOppenheimeretal.
2000andrefer-encestherein).
ThisisthecaseforCZTauB,V819TauB,HKTau/c,GGTaub,Haro6-28BandHBC604B.
WithrespecttotheSwensonetal.
(1994)modelthatdoesnotcovertheregioncloseaboveandbelowthehydrogenburn-ingmasslimitallsixmentionedobjectshavemassesbelow0.
15M⊙.
TheBaraeetal.
(1998)tracksyieldmassesofM≤0.
08M⊙forV819TauB,HKTau/c,GGTauBandHaro6-28B.
TheprimaryofHBC604couldnotbereli-ablycomparedtotheBaraeetal.
(1998)tracks,sowecannotgiveaBaraemassforthesecondary.
Weemphasizethatadenitiveclassicationofacom-panionasasubstellarobjectisnotpossibleontheba-sisofourdataandrequiresspatiallyresolvedspectraofthecomponents.
Ithasalreadybeenmentioned(Sect.
3.
2)thatbasedonNIRcolorswecannotdistinguishbetweenstarswithverylatespectraltypesanddeeplyembeddedobjects.
HKTau/cdenitelybelongstothelatterclassofobjects,becauseithasanedge-onseendiskdetectedbyStapelfeldtetal.
(1998).
Fortwooftheothermentionedobjects,namelythecompanionsofCZTauandHaro6-28,wehavedetectedunusuallylargeNIRcolorexcessesbyplacingthemintoacolor-colordiagram(seeFig.
1)whichmakesthemgoodcandidatesforheavilyextinctedobjects.
V819TauBmaybeachanceprojectedbackgroundstarashasbeenmentionedinSect.
4.
4.
Theapparentlowlumi-nositywouldinthiscasebetheresultofunderestimatingitsdistance.
Substellarcompanionstoyoungstarsprobablydoexist.
GGTaubhasbeenplacedintotheHRDbasedonspa-tiallyresolvedspectroscopybyWhiteetal.
(1999).
Theyderivedamassof0.
044±0.
006M⊙whichisinlinewithourmassestimateof0.
04M⊙forthisobjectderivedfromtheD'Antona&Mazzitelli(1998)andtheBaraeetal.
(1998)models.
Meyeretal.
(1997)haveestimatedamassof≈0.
06M⊙forthecompanionofDITauthathasbeendetectedbyGhezetal.
(1993).
Thissystemisnotwithinourobjectlistbecauseitsprojectedseparationof0.
′′12isbelowthediractionlimitofa3.
5mtelescopeintheK-band.
Therearenostrongsubstellarcompanioncandi-datesamongthecomponentscoveredbyourstudy.
6.
2.
ThemassfunctionforthecomponentsinTaurus-AurigaAmongTTauristarsintheTaurus-Aurigaassociationthereisasignicantoverabundanceofbinariescomparedtomainsequencestarsinthesolarneighbourhood(seeK¨ohler&Leinert1998andreferencestherein).
Ifthebinaryexcessdetectedwithlunaroccultationobservations,speckleinterferometryanddirectimagingisextrapolatedtowardsthewholerangeofprojectedseparationsonecomestotheconclusionthatnearlyallstarsinthisSFRbelongtomultiplesystems.
Itisthereforeinterestingtoderivethecomponents'massfunctionfortheTaurus-Aurigaassociation,becausethisshouldbeabetterrepresentationofthemassfunctioninthisSFRthanthesystems'massfunction-includingunresolvedbinaries-thathasbeengivenbyKenyon&Hartmann(1995).
ThemassfunctionsforthecomponentsofyoungmultiplesystemsinTaurus-AurigaforwhichwehavegivenmassesinTable2areplottedinFig.
6forthethreesetsofPMStracksused.
WehavenowtoasktowhatdegreethesemassfunctionscanberepresentativeofthewholebinarypopulationinthisSFR.
OursampleistakenfromLeinertetal.
(1993).
Itisrestrictedtosystemswithprojectedseparationsfrom0.
′′13to13′′andapparentmagnitudesKsys≤9.
5mag.
Fortherstrestrictiononehastoassumethatthecomponents'massesarenotafunctionoftheirseparation.
Thelatterrestrictionmeansthatwecande-tectallprimarieswithKsys≤10.
25mag(forauxratioI2/I1=1)whilethesecondariesarecompletetoamag-J.
Woitasetal.
:MassratiosofTTauristarcomponents9Table2.
Massesofthecomponentsinyoungbinarysystems.
TheyarederivedplacingthecomponentsintotheHRDasdescribedinSect.
5andcomparingtothePMSevolutionarytracksfromD'Antona&Mazzitelli(1998),Swensonetal.
(1994)andBaraeetal.
(1998).
Questionmarksindicatethatforthesesystemstheprimary'slocationintheHRDcouldnotbereliablycomparedtothePMStracks,becausethispositionfallsinaregionnotcoveredbytherespectivetracks.
SystemM1[M⊙]M2[M⊙]M1[M⊙]M2[M⊙]M1[M⊙]M2[M⊙]DM98SwensonBaraeHBC3510.
85±0.
10.
25±0.
11.
0±0.
10.
4±0.
11.
0±0.
10.
4±0.
1HBC352/3531.
0±0.
050.
9±0.
05HBC358Aa0.
35±0.
10.
35±0.
10.
7±0.
050.
7±0.
050.
4±0.
10.
4±0.
1HBC358B0.
4±0.
10.
7±0.
050.
5±0.
1HBC360/3610.
2±0.
050.
2±0.
050.
5±0.
10.
5±0.
10.
3±0.
10.
3±0.
1FOTau0.
35±0.
050.
14±0.
040.
5±0.
10.
35±0.
10.
6±0.
10.
3±0.
1DDTau0.
5±0.
10.
4±0.
10.
7±0.
10.
65±0.
10.
7±0.
10.
6±0.
1CZTau0.
4±0.
10.
04±0.
040.
7±0.
10.
514±3.
79±3.
0M2/M1≤0.
512±3.
510±3.
2Swensonetal.
(1994)M2/M1>0.
516±4.
09±3.
0M2/M1≤0.
510±3.
28±2.
8Baraeetal.
(1998)M2/M1>0.
517±4.
18±2.
8M2/M1≤0.
58±2.
86±2.
5dividualmassratios(Table3)isaboutonebinsize.
Thiseectwillcauseaatteningofanygivendistribution.
Wewillconcludethisdiscussionwiththestatementthatourdatadoesnotsupportthepreferenceofanymassratios.
Ontheotherhandweadmitthatitwouldbeprematuretosaythatthemassratiodistributionisdenetelyattakingintoaccountthelargedierencesbetweenthedis-tributionsshowninFig.
7.
Aatdistributionofmassratiosissupportedbythedistri-butionofK-banduxratios(Fig.
7,lowerrightpanel).
Forlow-massPMSstarsthereisaK-bandmass-luminosityrelationofaboutLM(e.
g.
Simonetal.
1992),sothedistributionofthisquantityshouldinagoodapproxi-mationresemblethatofthemassratios.
ThereisagainnoclusteringtowardsM2/M1=1.
IfalsothesystemswithK>2.
5,i.
e.
F2(K)/F1(K)0.
515±3.
98±2.
8M2/M1≤0.
511±3.
311±3.
3Swensonetal.
(1994)M10.
513±3.
611±3.
3M2/M1≤0.
55±2.
213±3.
6Baraeetal.
(1998)M10.
510±3.
215±3.
9M2/M1≤0.
56±2.
58±2.
8berofobjectsinbothgroupsforeachtheoreticalPMSmodelconsidered.
WithregardtotheBaraeetal.
(1998)modelthebehaviourofbothgroupsisthesame.
TheD'Antona&Mazzitelli(1998)andSwensonetal.
(1994)modelssuggestapreferenceofhighermassratiosforlowerprimarymasses.
ThelatterresulthasalsobeenmentionedbyLeinertetal.
(1993)onthebasisofKbandmagnitudesanduxratios.
Weconcludethatcorrelationsbetweenmassratioandotherbinaryparametersareweakiftheyexistatall.
7.
Discussion7.
1.
TheoreticalmodelsformultiplestarformationItisnowwidelybelievedthatfragmentationduringpro-tostellarcollapseisthemajorprocessforformingmultiplestarsinlow-densitySFRsasdiscussedhere(e.
g.
Clarkeetal.
2000).
Ourresultsgenerallyareinlinewiththisas-sumption:–Wehavesomeadditionalsupportfromourdataforco-evalformationofthecomponents(Sect.
4.
4).
Captureprocessesofindependentlyformedsinglestars(thatwouldproduceawidespreaddistributionofrelativeages)shouldnotplayadominantroleintheforma-tionofthebinariesdiscussedhere.
–ThereareonlyafewcompanionswithmassesM≤0.
1M⊙whichisatypicalmassofaTTauristars'disk(Beckwithetal.
1990).
Furthermoretheselowmasscompanionsdonotpreferentiallyoccuratseparationsd≤100AUthatarecomparabletotypi-caldiskradii.
Thisisdiculttoreconcilewiththeideathatalargenumberofcompanionsisformedfromdiskinstabilities.
–Fragmentationduringprotostellarcollapsedoesnotleadtoapreferenceofdistinctmassratiosortoadependenceofmassratiofromotherbinaryparam-eterslikethecomponents'separation(e.
g.
Ghezetal.
2000).
Wehaveindeednotseenanysuchcorrela-tions(Sect.
6.
3).
Regardingthelastitemonehashowevertoconsiderthatthereisalargetimespanbetweentheendofnu-mericalsimulationsoffragmentationduringprotostellarcollapseandthestateofdynamicallystableTTaurimul-tiplesystemsasobservedbyus.
Particularly,attheendofthesimulationspresentede.
g.
byBurkertetal.
(1996)only≈10%oftheparentcloud'smasshascondensedintofragments.
Thereforeitisahighlyimportantquestionhowsubsequentaccretionprocessesinuencethepropertiesofyoungmultiplesystems.
Sinceitisnotpossibletodaytocovertheentireevolutionofamolecularcloudcoreintoabinarysystemwithonesimulation,theoryhastotakeadierentapproach.
ForthispurposeBate(1997,1998)andBate&Bonnell(1997)havesimulatedthebehaviourofa"binary"formedoutoftwopointmassesthataresituatedinacavitywithinasurroundinggassphere.
Themassratioofthebinaryandtheangularmomentumoftheinfallingma-terialarevariableinitialconditions.
Theresultofthesesimulationsisthatinthecourseoftheaccretionprocessthesystem'smassratioincreasesandapproachesunityifthetotalcloudmassisaccreted.
Massratiosclosetounityshouldbemoreprobableinclosesystemsthanforwidepairs.
Thisisnotinagreementwithourresult(Sect.
6.
3)thatthereisnosignicantpreferenceofmassratiosclosetounityandthatthemassratioisprobablyindependentofthecomponents'separation.
SoitseemsthattheinitialconditionsusedbyBate&Bonnellaresomehowunrealis-ticandthatthe"nal"stellarmassesaremoredependentonthefragmentmassesthanonthefollowingaccretionprocesses.
Oneexplanationforthiscouldbethatinthecourseofprotobinaryevolutionmostoftheinitialmassiscondensedintofragments,beforeaccretionbecomesim-portant.
Anotherideaisthatthereissomeprocessthathaltsaccretionbeforealargeamountoftheremainingcloudmassisaccretedontothefragments.
Inanycaseourknowledgeaboutthisissueispreliminaryandaddi-tionaltheoreticalandobservationaleortisnecessarytodecidewhatphysicalprocessesdeterminestellarmasses.
7.
2.
ImplicationsforbinarystatisticsMultiplicitysurveysbyLeinertetal.
(1993)andGhezetal.
(1993)ledtothesurprisingresultthatthereisasig-nicantoverabundanceofbinariesintheTaurus-AurigaSFRcomparedtomainsequencestarsinthesolarneigh-bourhood.
Thisresultwasfurtherprovedbythefollow-upstudiesdonebySimonetal.
(1995)andK¨ohler&Leinert(1998).
Althoughthispaperisnotdirectlyconcernedwithbinarystatistics,wecandrawsomeconclusionsthatfur-thersupporttheideathatthisbinaryexcessisrealandnotaresultofobservationalbiases.
IfonecomparesthebinaryfrequencyamongyoungandevolvedstarsonehastotakeintoaccountthatduetoevolutionaryeectscompanionscanberelativelybrightintheirPMSphase,butinvisibleonthemainsequencestage.
Thisisparticularlythecaseforsubstellarcompan-ions.
Onehasfurthertoconsiderthatthemultiplicitysur-14J.
Woitasetal.
:MassratiosofTTauristarcomponentsveysweredoneatinfraredwavelengthsinSFRs,butintheopticalrangeformainsequencestars.
Sotheremightbeabiasthatsupportsthedetectionofveryred"infraredcom-panions"(IRCs,seeSect.
3.
2)inthevicinityofPMSstars.
AnotherproblemisthatthesurveysinTaurus-Aurigaandthesolarneighbourhoodcouldbenotdirectlycomparableiftheyweresensitivetoadierentrangeofmassratiosandthusstellarmasses.
IfthepresenceofsubstellarcompanionsorIRCsinthevicinityofTTauristarsinTaurus-Aurigawereacommonphenomenonthiscouldatleastpartiallyexplaintheob-servedbinaryexcessinthisSFR.
OurresultspresentedinSect.
3.
2and6.
1showthatthisisnotthecase:K¨ohler&Leinert(1998)havefoundthatafterapplyingastatisticalcorrectionforchanceprojectedbackgroundstarsthereare48.
9±5.
3companionsper100primaries(includingsinglestars)inTaurus-Auriga.
Wehavedenotedonly5outof40companions(forwhichwehavegivenmassesinTable2)ascandidatesforsubstellarobjectsbasedonmassesde-rivedfromtheD'Antona&Mazzitelli(1998)PMSevo-lutionarytracks(Sect.
6.
1).
WithrespecttotheBaraeetal.
(1998)modelthisnumberisevenlower.
Ifwetakethementioned5outof40companionsasanestimatefortherealnumberofbrowndwarfcompanionsinTaurus-AurigaandsubtractthisfromthecompanionfrequencygivenbyK¨ohler&Leinert(1998)thisvaluediminishesto42.
8±6.
0.
Thisisstillfarabovethevalueof25.
3±3.
9thatwasgivenbyDuquennoy&Mayor(1991)forG-dwarfsinthesolarneighbourhood.
Furthermorewehavefoundthatonly3outof51companionsinTaurus-AurigaaredetectableintheH-bandandatlongerwavelengths,butweremissedat1.
25m,soIRCsareprobablynotafre-quentphenomenon.
ThebinaryfrequencydoesnothavetobecorrectedforIRCs,becausetheirsuccessorsinthemainsequencephasewillbe"normal"stellarcompanions(seeKoreskoetal.
1997forestimatesofIRCs'masses).
Duquennoy&Mayor(1991)haveclaimedthattheirsampleiscompleteformassratiosM2/M1≥0.
1.
IthasalreadybeenmentionedbyK¨ohler&Leinert(1998,Sect.
5.
2)thatthecompletenesslimitofthebinarysurveysinTaurus-Aurigaisinanycasenotlower,theactualvaluedependentonthemass-luminosityrelationused.
Wecanfurtherprovethisresult,becausethereareonly2outof51systemswithmassratioslessthan0.
1withrespecttotheD'Antona&Mazzitelli(1998)PMSmodeland1outof50consideringtheBaraeetal.
(1998)tracks(Table3).
WeconcludethattheobservedbinaryexcessinTaurus-Aurigacomparedtonearbymainsequencestarsisneithertheresultofahighersensitivityinmassrationoraconse-quenceofalargefrequencyofsubstellarorinfraredcom-panions.
ThestrangeoverabundanceofbinariesinTaurus-AurigaremainsafactalsoafterthismoredetailedanalysisofthesystemsfoundbyLeinertetal.
(1993).
8.
SummaryFromspeckleinterferometryanddirectimagingwehavederivedresolvedJHKphotometryfortheindividualcom-ponentsofTTauribinarysystemsinnearbystarform-ingregions.
Thesemeasurementsarecombinedwithotherdatatakenfromliterature(resolvedJHKphotometryfromotherauthors,systemmagnitudesandspectraltypes,ex-tinctioncoecients)tostudypropertiesofthecompo-nentsinyoungbinarysystems.
Themainresultsare:–Wehavefoundonlyveryfewunusuallyredobjectsthatmaybeyoungsubstellarobjectsorinfraredcompan-ions.
TheirnumberistoosmalltohavesignicantlyinuencedthebinarystatisticsinTaurus-Auriga.
–TheplacementofthecomponentsintoNIRcolormag-nitudediagramsisaectedbylargeerrorsandthusal-lowsnoprecisedeterminationofstellaragesfromPMSevolutionarymodels.
Wecanhoweverdetectproblem-aticcasesandndthatV819TauBisprobablyanun-relatedbackgroundobject.
Thelocationsofthecom-ponentsofthe16otherWTTSsystemsintothetheCMDsareinlinewiththeassumptionthatallcompo-nentswithinasystemarecoeval.
–ThedeterminationofmassesfromtheHRDhasbeenperformedusingthefollowingprocedure:WederivestellarluminositiesfromtheJ-bandmagnitudes,assigntheopticalsystemspectraltypetotheprimaryandusetheassumptionthatallcomponentswithinonesystemarecoeval.
–TheuseofthreedierentsetsofPMStracksthenyieldsmassfunctionsthataredierentatthe99%con-dencelevel.
Forthisreasonwediscusstheresultsofallthreemodelsusedseparately.
Thesedierencestendtobelargerthantheuncertaintiesresultingfromob-servationalerrors.
Inaddition,thelattermasserrorsarerandomandthuspartiallycancelinastatisticaldiscussion.
–Withintheuncertaintiesthedistributionofmassra-tiosisatforM2/M1≥0.
2.
Therearenosignicantcorrelationsbetweenmassratioandprojectedsepara-tionormassratioandprimarymass.
Theseresultsareinlinewiththewideleyacceptedideathatbinariesareformedbyfragmentationduringprotostellarcol-lapseprocesses.
Moreover,theysuggestthatthenalmassesofthecomponentsarelargelydeterminedbyfragmentationitselfandnotbysubsequentaccretion.
Acknowledgements.
WearegratefultoAndreasEckartandKlausBickertfortheirsupportinobservingwiththeSHARPcamera.
WealsothankthestaatESOLaSillaandCalarAltofortheirsupportduringseveralobservingruns.
TheauthorsappreciatefruitfuldiscussionswithMichaelMeyer,MonikaPetr,MatthewBateandCorynBailer-Jones,andtheythankananonymousrefereeforpointedandproductivecomments.
ThisresearchhasmadeuseoftheSIMBADdatabase,operatedatCDS,France.
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,1999,AJ117,354AppendixA:Near-infraredphotometryforthecomponentsofyoungbinarysystemsThespatiallyresolvedobservationsofTTauribinarysys-temsobtainedbytheauthorsarelistedinTableA1.
Column1givesthemostcommonnameoftheob-ject,columns2and3thewavelengthbandandthedateofobservation,column4thebrightnessratio(sec-ondary/primary,usuallybutnotalways<1),columns5through7themagnitudeofsystem,primaryandsec-ondarycomponentsintherespectivewavelengthband.
TableA2containstheadoptednear-infraredmagni-tudesofthecomponentsoftheyoungbinarysystemswhichcomposeoursample.
Thevaluesgivenherearethemeanofallspatiallyresolvedphotometricobserva-tions,i.
e.
ourdatafromTableA.
1andmeasurementspublishedbyChellietal.
(1995),Duchene(1999a),Ghezetal.
(1993,1997a,1997b),Haasetal.
(1990),Hartiganetal.
(1994),K¨ohleretal.
(2000),Moneti&Zinnecker(1991),Richichietal.
(1999),Roddieretal.
(1996)andSimonetal.
(1992).
ThevaluesforvisualextinctionAVandthespectraltypegivenwiththeprimaries,belongtothesys-tems(seeSect.
2.
1forreferences).
Thenumbersinthelastcolumndenotethestarformingregion:Taurus-Auriga(1),UpperScorpius(2),ChamaeleonI(3)andLupus(4).
16J.
Woitasetal.
:MassratiosofTTauristarcomponentsTableA.
1.
SpatiallyresolvedobservationsofyoungTTauribinarysystemsobtainedbytheauthors.
SystemFilterDateI2/I1mSysmPrimmSecHBC351J30Sep19930.
165±0.
0049.
92±0.
0510.
09±0.
0512.
04±0.
07H8.
Jan19930.
190±0.
0159.
30±0.
029.
49±0.
0311.
29±0.
09K16.
Feb19920.
22±0.
029.
159.
37±0.
0211.
01±0.
08HBC358BJ5.
Oct199311.
33±0.
06H8.
Jan199310.
75±0.
06K16.
Feb199210.
44±0.
09LkCa3J5.
Oct19930.
62±0.
028.
478.
99±0.
019.
51±0.
02H27.
Sep19910.
60±0.
037.
74±0.
018.
25±0.
038.
80±0.
0429.
Sep19960.
885±0.
0118.
43±0.
028.
56±0.
02K6.
Dec19900.
57.
52±0.
057.
96±0.
058.
71±0.
0519.
Nov19970.
755±0.
0078.
13±0.
058.
44±0.
06V773TauJ5.
Oct19930.
113±0.
0057.
65±0.
057.
77±0.
0510.
13±0.
09H8.
Jan19930.
15±0.
026.
85±0.
097.
00±0.
119.
06±0.
22FOTauJ7.
Oct19930.
30±0.
019.
70±0.
079.
99±0.
0811.
28±0.
0929.
Nov19960.
55±0.
0510.
18±0.
1110.
83±0.
1416.
Nov19970.
63±0.
0210.
23±0.
0810.
73±0.
09H7.
Jan19930.
93±0.
038.
71±0.
059.
42±0.
079.
50±0.
0716.
Nov19970.
698±0.
0149.
28±0.
069.
68±0.
06K19.
Sep19910.
92±0.
048.
18±0.
038.
89±0.
058.
98±0.
0514.
Dec19940.
72±0.
028.
76±0.
049.
13±0.
059.
Oct19950.
648±0.
0188.
72±0.
049.
19±0.
0527.
Sep19960.
628±0.
0198.
71±0.
049.
21±0.
05DDTauJ5.
Dec19900.
79±0.
019.
47±0.
0410.
10±0.
0510.
36±0.
05H5.
Dec19900.
79±0.
018.
52±0.
079.
15±0.
089.
41±0.
08K5.
Dec19900.
64±0.
017.
87±0.
078.
41±0.
088.
89±0.
08CZTauJ29.
Nov19960.
120±0.
00510.
51±0.
1210.
63±0.
1212.
94±0.
16H9.
Jan19930.
23±0.
019.
74±0.
039.
96±0.
0411.
56±0.
07K19.
Mar19920.
46±0.
039.
28±0.
039.
69±0.
0510.
53±0.
0828.
Sep19960.
183±0.
0049.
46±0.
0311.
30±0.
04FQTauJ16.
Nov19971.
06±0.
0110.
61±0.
0211.
39±0.
0311.
33±0.
02H27.
Sep19911.
239.
90±0.
0710.
77±0.
0710.
55±0.
0716.
Nov19971.
109±0.
01610.
71±0.
0810.
60±0.
08K22.
Sep19910.
90±0.
019.
47±0.
3110.
17±0.
3210.
28±0.
32V819TauJ2.
Oct19939.
45±0.
0312.
96±0.
06H2.
Oct19938.
76±0.
0812.
39±0.
08LkCa7J5.
Oct19930.
414±0.
0089.
259.
63±0.
0110.
58±0.
01H27.
Sep19910.
44±0.
028.
588.
98±0.
029.
87±0.
03K19.
Sep19910.
56±0.
028.
36±0.
038.
84±0.
049.
47±0.
05FSTauJ29.
Nov19960.
188±0.
00710.
66±0.
1310.
85±0.
1412.
66±0.
16H28.
Sep19960.
183±0.
0089.
14±0.
099.
32±0.
1011.
17±0.
13K19.
Nov19970.
138±0.
0057.
74±0.
267.
88±0.
2610.
03±0.
29FWTauH27.
Sep19960.
76±0.
109.
7810.
39±0.
0610.
69±0.
08K17.
Oct19891.
00±0.
019.
3710.
12±0.
0110.
12±0.
0113.
Dec19940.
61±0.
109.
89±0.
0710.
42±0.
119.
Oct19951.
00±0.
0510.
12±0.
0310.
12±0.
03FVTauJ1.
Sep19900.
71±0.
059.
51±0.
1010.
09±0.
1310.
46±0.
1430.
Nov19960.
38±0.
049.
86±0.
1310.
91±0.
18H1.
Sep19900.
68±0.
028.
22±0.
138.
78±0.
149.
20±0.
15K1.
Sep19900.
83±0.
017.
37±0.
108.
03±0.
118.
23±0.
119.
Oct19950.
695±0.
0077.
94±0.
108.
34±0.
11FVTau/cH9.
Jan19910.
039.
42±0.
029.
45±0.
0213.
26±0.
03K9.
Oct19950.
076±0.
0048.
80±0.
028.
88±0.
0211.
68±0.
03UXTauACJ16.
Nov19978.
97±0.
0911.
85±0.
09FXTauJ20.
Mar19910.
93±0.
039.
16±0.
069.
87±0.
089.
95±0.
0830.
Nov19960.
934±0.
0049.
88±0.
069.
95±0.
06H20.
Mar19910.
78±0.
018.
75±0.
149.
37±0.
159.
65±0.
1516.
11.
19970.
775±0.
0129.
37±0.
159.
65±0.
15J.
Woitasetal.
:MassratiosofTTauristarcomponents17TableA.
1.
continuedSystemFilterDateI2/I1mSysmPrimmSecFXTauK4.
Dec19900.
54±0.
058.
14±0.
148.
61±0.
189.
28±0.
2120.
Mar19910.
56±0.
018.
63±0.
159.
25±0.
1518.
Oct19910.
509±0.
0018.
59±0.
149.
32±0.
14DKTauJ16.
Nov19979.
15±0.
0910.
52±0.
10LkHα331J26.
Jan19940.
706±0.
0239.
8510.
43±0.
0110.
81±0.
02H6.
Jan19930.
91±0.
028.
999.
69±0.
019.
79±0.
0129.
Sep19960.
70±0.
019.
57±0.
019.
95±0.
01K29,Oct19910.
73±0.
048.
689.
28±0.
039.
62±0.
039.
Oct19950.
66±0.
039.
23±0.
029.
68±0.
03XZTauJ27.
Jan19941.
51±0.
039.
91±0.
3210.
91±0.
3310.
46±0.
3330.
Nov19963.
54±0.
3111.
55±0.
3910.
18±0.
34K28.
Jan19940.
41±0.
018.
05±0.
568.
42±0.
579.
39±0.
5822.
Nov19970.
316±0.
0078.
35±0.
579.
60±0.
58HKTauG2J26.
Jan19940.
764±0.
0239.
41±0.
0910.
03±0.
1010.
32±0.
11H6.
Jan19930.
69±0.
078.
44±0.
069.
01±0.
109.
41±0.
1327.
Jan19940.
85±0.
129.
11±0.
139.
28±0.
1427.
Sep19960.
76±0.
059.
05±0.
099.
35±0.
10K28.
Sep19910.
88±0.
038.
05±0.
028.
74±0.
048.
87±0.
049.
Oct19950.
85±0.
068.
72±0.
038.
89±0.
0419.
Nov19970.
587±0.
0178.
55±0.
039.
13±0.
04GGTauAaJ27.
Jan19940.
543±0.
0049.
01±0.
079.
48±0.
0110.
14±0.
01H2.
Nov19910.
549±0.
0097.
83±0.
058.
31±0.
068.
96±0.
0624.
Sep19940.
417±0.
0178.
31±0.
058.
95±0.
06K2.
Nov19900.
64±0.
017.
30±0.
037.
84±0.
048.
32±0.
0421.
Oct19910.
32±0.
057.
77±0.
048.
44±0.
0616.
Nov19970.
564±0.
0047.
79±0.
038.
41±0.
0310.
Oct19980.
476±0.
0057.
72±0.
038.
53±0.
04GGTauBbJ27.
Jan199411.
44±0.
0613.
12±0.
09H10.
Jan199310.
26±0.
0612.
58±0.
06K2.
Nov19909.
99±0.
1011.
79±0.
10UZTauwJ26.
Jan19940.
76±0.
079.
6410.
25±0.
0410.
55±0.
06H9.
Jan19930.
69±0.
028.
679.
24±0.
019.
64±0.
0229.
Sep19960.
66±0.
029.
22±0.
019.
67±0.
02GHTauJ26.
Jan19940.
89±0.
019.
22±0.
089.
91±0.
0910.
04±0.
09H6.
Jan19931.
30±0.
108.
34±0.
079.
24±0.
128.
96±0.
1129.
Sep19961.
03±0.
109.
11±0.
129.
08±0.
1227.
Oct19910.
91±0.
048.
48±0.
158.
58±0.
15Elias12J27.
Jan19940.
579±0.
0228.
22±0.
048.
72±0.
069.
31±0.
07H5.
Jan19930.
54±0.
017.
41±0.
027.
88±0.
038.
55±0.
0329.
Sep19960.
58±0.
047.
91±0.
058.
50±0.
07K25.
Sep19910.
460±0.
0086.
95±0.
027.
36±0.
038.
20±0.
0326.
Oct19910.
45±0.
027.
35±0.
038.
22±0.
05ISTauJ26.
Jan19940.
32±0.
0110.
2610.
56±0.
0111.
80±0.
0329.
Nov19960.
21±0.
0110.
47±0.
0112.
16±0.
04H9.
Jan19930.
36±0.
039.
259.
58±0.
0210.
69±0.
0729.
Sep19960.
20±0.
019.
45±0.
0111.
20±0.
05K9.
Jan19930.
21±0.
028.
688.
87±0.
0210.
58±0.
099.
Oct19950.
165±0.
0048.
85±0.
0110.
80±0.
01CoKuTau3J16.
Nov199711.
19±0.
0912.
30±0.
09H27.
Sep19919.
3410.
89HBC412J27.
Jan19940.
82±0.
1110.
0610.
71±0.
0710.
93±0.
08H6.
Jan19930.
90±0.
029.
3310.
03±0.
0110.
14±0.
01K19.
Mar19921.
00±0.
029.
109.
85±0.
019.
85±0.
01Haro6-28J27.
Jan19940.
20±0.
0111.
0811.
28±0.
0113.
03±0.
05H6.
Jan19930.
44±0.
0110.
01±0.
0610.
41±0.
0711.
30±0.
08K16.
Feb19920.
63±0.
039.
27±0.
029.
80±0.
0410.
30±0.
05VYTauJ29.
Nov19960.
306±0.
0069.
86±0.
2910.
15±0.
2911.
44±0.
3118J.
Woitasetal.
:MassratiosofTTauristarcomponentsTableA.
1.
continuedSystemFilterDateI2/I1mSysmPrimmSecH22.
Sep19910.
24±0.
019.
26±0.
179.
49±0.
1811.
04±0.
1828.
Sep19960.
26±0.
019.
51±0.
1810.
97±0.
20K5.
Dec19900.
26±0.
028.
97±0.
169.
22±0.
1810.
68±0.
23IWTauJ27.
Jan19941.
24±0.
049.
3310.
21±0.
029.
97±0.
02H8.
Jan19930.
93±0.
028.
619.
32±0.
019.
40±0.
0128.
Sep19961.
30±0.
159.
51±0.
079.
23±0.
05K28.
Oct19910.
91±0.
048.
35±0.
029.
05±0.
049.
15±0.
04LkHα332G1J29,Nov19960.
511±0.
0269.
64±0.
0110.
09±0.
0310.
82±0.
05H10.
Nov19920.
62±0.
018.
68±0.
039.
20±0.
049.
72±0.
0428.
Sep19960.
560±0.
0099.
16±0.
049.
79±0.
04K27.
Oct19910.
58±0.
038.
18±0.
058.
68±0.
079.
27±0.
0912.
Dec19940.
555±0.
0068.
66±0.
059.
30±0.
0622.
Nov19970.
51±0.
028.
63±0.
069.
36±0.
08LkHα332G2J27.
Jan19940.
458±0.
0039.
44±0.
029.
85±0.
0210.
70±0.
02H10.
Nov19920.
509±0.
0238.
35±0.
048.
80±0.
069.
53±0.
0728.
Sep19960.
411±0.
0128.
72±0.
059.
69±0.
06K27.
Oct19910.
60±0.
057.
88±0.
078.
39±0.
108.
94±0.
1315.
Dec19940.
530±0.
0178.
34±0.
089.
03±0.
0917.
Nov19970.
465±0.
0228.
29±0.
099.
13±0.
11LkHα332J27.
Jan19940.
80±0.
049.
81±0.
0210.
45±0.
0510.
69±0.
05H10.
Nov19920.
56±0.
068.
61±0.
069.
09±0.
109.
72±0.
1327.
Jan19940.
65±0.
049.
15±0.
099.
62±0.
1028.
Sep19960.
485±0.
0159.
04±0.
079.
82±0.
08K27.
Oct19910.
23±0.
037.
83±0.
088.
05±0.
119.
65±0.
2022.
Nov19970.
46±0.
018.
24±0.
099.
08±0.
10Haro6-37/cH8.
Jan19989.
51±0.
06K8.
Jan19988.
97±0.
08RWAurJ30Sep19930.
30±0.
028.
38±0.
218.
66±0.
239.
97±0.
27H9Jan19930.
37±0.
027.
53±0.
067.
87±0.
088.
95±0.
10K28Nov19910.
23±0.
016.
83±0.
157.
05±0.
208.
65±0.
23NTTS155203-2338J5.
May19980.
102±0.
0067.
56±0.
027.
67±0.
0310.
14±0.
08H5.
May19980.
121±0.
0077.
15±0.
027.
27±0.
039.
57±0.
08NTTS155808-2219J7.
May19980.
585±0.
0199.
73±0.
0210.
23±0.
0310.
81±0.
04H7.
May19980.
575±0.
0089.
02±0.
029.
51±0.
0310.
11±0.
03NTTS155808-2219J7.
May19980.
585±0.
0199.
73±0.
0210.
23±0.
0310.
81±0.
04H7.
May19980.
575±0.
0089.
02±0.
029.
51±0.
0310.
11±0.
03NTTS155913-2233J7.
May19980.
548±0.
0148.
84±0.
029.
31±0.
039.
97±0.
04H7.
May19980.
577±0.
0168.
23±0.
028.
72±0.
039.
32±0.
04NTTS160735-1857J8.
May19980.
656±0.
0199.
72±0.
0210.
27±0.
0310.
73±0.
04H8.
May19980.
584±0.
0218.
98±0.
029.
48±0.
0310.
06±0.
05NTTS160946-1851J8.
May19980.
210±0.
0078.
27±0.
028.
48±0.
0310.
17±0.
05H8.
May19980.
194±0.
0097.
65±0.
027.
84±0.
039.
62±0.
06RXJ1546.
1-2804H7.
May19980.
537±0.
0167.
517.
98±0.
018.
65±0.
02RXJ1549.
3-2600H7.
May19980.
443±0.
0038.
158.
55±0.
019.
43±0.
01RXJ1601.
7-2049H13.
May19980.
504±0.
0128.
829.
26±0.
0110.
01±0.
02RXJ1600.
5-2027H7.
May19980.
735±0.
0219.
139.
73±0.
0110.
06±0.
02RXJ1601.
8-2445H7.
May19980.
595±0.
0308.
719.
22±0.
029.
78±0.
03RXJ1603.
9-2031BH7.
May19980.
666±0.
0228.
949.
49±0.
019.
94±0.
02RXJ1604.
3-2130BH7.
May19980.
471±0.
0049.
8210.
24±0.
0111.
06±0.
01WXChaJ7.
May19980.
226±0.
01710.
0010.
22±0.
0211.
84±0.
07H7.
May19980.
188±0.
0079.
019.
20±0.
0111.
01±0.
03VWChaABJ5.
May19980.
573±0.
0228.
739.
22±0.
029.
83±0.
03H5.
May19980.
432±0.
0197.
668.
05±0.
018.
96±0.
03HMAnonJ5.
May19980.
205±0.
0028.
798.
99±0.
0110.
71±0.
01H5.
May19980.
240±0.
0068.
158.
38±0.
019.
93±0.
02HNLupJ7.
May19980.
831±0.
0449.
24±0.
109.
90±0.
1310.
10±0.
13H7.
May19980.
628±0.
0138.
04±0.
108.
57±0.
119.
07±0.
11J.
Woitasetal.
:MassratiosofTTauristarcomponents19TableA.
2.
NIRphotometryforcomponentsofyoungbinarysystems.
Thevaluesgivenherearethemeanofallspatiallyresolvedphotometricobservations,i.
e.
ourdatafromTableA.
1andmeasurementspublishedbyChellietal.
(1995),Duchene(1999a),Ghezetal.
(1993,1997a,1997b),Haasetal.
(1990),Hartiganetal.
(1994),K¨ohleretal.
(2000),Moneti&Zinnecker(1991),Richichietal.
(1999),Roddieretal.
(1996)andSimonetal.
(1992).
ThevaluesforAVandthespectraltypegivenfortheprimaries,belongtothesystems(seeSect.
2.
1forreferences).
ThenumbersinthelastcolumndenoteTaurus-Auriga(1),UpperScorpius(2),ChamaeleonI(3)andLupus(4).
SystemComponentJHKAVSpectraltypeSFRHBC351A10.
09±0.
059.
49±0.
039.
37±0.
020.
00K51B12.
04±0.
0711.
29±0.
0911.
01±0.
08HBC352/10.
12±0.
049.
76±0.
039.
62±0.
020.
87G01HBC35310.
47±0.
0210.
04±0.
039.
91±0.
03HBC358A11.
51±0.
0610.
87±0.
0510.
60±0.
060.
21M21a11.
56±0.
0610.
94±0.
0510.
69±0.
06B11.
33±0.
0610.
75±0.
0610.
44±0.
09HBC360/10.
83±0.
0810.
24±0.
089.
98±0.
080.
28M31HBC36110.
9610.
3710.
11LkCa3A8.
99±0.
018.
34±0.
098.
11±0.
080.
42M11B9.
51±0.
028.
68±0.
128.
48±0.
12V773TauA7.
77±0.
057.
03±0.
036.
77±0.
091.
32K31B10.
13±0.
098.
91±0.
158.
09±0.
31FOTauA10.
13±0.
079.
35±0.
078.
76±0.
031.
87M21B10.
95±0.
179.
59±0.
099.
14±0.
04DDTauA10.
10±0.
059.
15±0.
088.
37±0.
040.
76M11B10.
36±0.
059.
41±0.
088.
96±0.
07CZTauA10.
63±0.
129.
96±0.
049.
58±0.
121.
32M1.
51B12.
94±0.
1611.
56±0.
0710.
92±0.
39FQTauA11.
39±0.
0310.
74±0.
0310.
17±0.
321.
87M21B11.
33±0.
0210.
58±0.
0310.
28±0.
32V819TauA9.
45±0.
038.
76±0.
088.
501.
35K71B12.
96±0.
0612.
39±0.
0812.
14LkCa7A9.
63±0.
018.
98±0.
028.
84±0.
040.
59K71B10.
58±0.
019.
87±0.
039.
47±0.
05FSTauA10.
85±0.
149.
32±0.
107.
88±0.
261.
84M11B12.
66±0.
1611.
17±0.
1310.
03±0.
29TTauA7.
26±0.
226.
36±0.
145.
56±0.
181.
39K01B8.
81±0.
116.
52±0.
11FVTauA9.
98±0.
128.
78±0.
147.
96±0.
044.
72K51B10.
69±0.
239.
20±0.
158.
32±0.
05FVTau/cA9.
45±0.
028.
93±0.
053.
40M3.
51B13.
26±0.
0211.
29±0.
40Haro6-10A9.
88±0.
039.
13±0.
317.
89±0.
044.
78K31B12.
02±0.
4410.
71±0.
56FWTauA10.
39±0.
0610.
04±0.
080.
35M41B10.
69±0.
0810.
22±0.
10UXTauA9.
00±0.
108.
06±0.
107.
54±0.
100.
21K21B11.
14±0.
1010.
10±0.
039.
42±0.
04b11.
42±0.
1010.
27±0.
039.
55±0.
04C11.
85±0.
0910.
8410.
43FXTauA9.
88±0.
019.
37±0.
018.
61±0.
021.
08M11B9.
95±0.
019.
65±0.
019.
28±0.
02DKTauA9.
15±0.
098.
10±0.
027.
32±0.
110.
76K71B10.
52±0.
109.
43±0.
038.
73±0.
04LkHα331A10.
43±0.
019.
63±0.
069.
26±0.
030.
38M5.
51B10.
81±0.
029.
87±0.
089.
65±0.
03XZTauA11.
04±0.
279.
44±0.
178.
41±0.
032.
91M31B10.
43±0.
1410.
07±0.
209.
44±0.
0820J.
Woitasetal.
:MassratiosofTTauristarcomponentsTableA.
2.
continuedSystemComponentJHKAVSpectraltypeSFRHKTau10.
41±0.
239.
13±0.
228.
42±0.
202.
32M0.
51HKTau/c13.
66±0.
2012.
18±0.
2011.
77±0.
20V710TauA9.
82±0.
169.
06±0.
168.
69±0.
160.
87M11B10.
20±0.
279.
21±0.
278.
82±0.
27HKTauG2A10.
03±0.
109.
05±0.
038.
64±0.
051.
87M0.
51B10.
32±0.
119.
35±0.
049.
00±0.
07GGTauA9.
39±0.
098.
29±0.
097.
79±0.
050.
76M01a10.
16±0.
029.
05±0.
088.
58±0.
08B11.
41±0.
1610.
55±0.
1510.
11±0.
120.
76M4.
5b13.
24±0.
1212.
64±0.
0612.
01±0.
22UZTauwA10.
25±0.
049.
23±0.
018.
80±0.
020.
83M31B10.
55±0.
069.
66±0.
029.
41±0.
03UZTaue9.
83±0.
028.
46±0.
027.
59±0.
021.
49M1GHTauA9.
91±0.
099.
18±0.
078.
69±0.
210.
52M21B10.
04±0.
099.
02±0.
068.
42±0.
16Elias12A8.
72±0.
067.
90±0.
027.
33±0.
022.
87K71B9.
31±0.
078.
53±0.
038.
26±0.
05ISTauA10.
52±0.
059.
52±0.
078.
85±0.
014.
17K21B11.
98±0.
1810.
95±0.
0310.
74±0.
08GKTau/9.
02±0.
168.
02±0.
077.
31±0.
230.
87K71GITau9.
42±0.
088.
46±0.
077.
79±0.
18HNTauA10.
82±0.
359.
49±0.
348.
44±0.
330.
89K51B12.
6212.
0511.
62CoKuTau3A11.
19±0.
099.
348.
533.
26M11B12.
30±0.
0910.
899.
87HBC412A10.
71±0.
0710.
03±0.
019.
85±0.
010.
69M21B10.
93±0.
0810.
14±0.
019.
85±0.
01HPTauG2/8.
19±0.
097.
49±0.
087.
28±0.
070.
67G01HPTauG310.
13±0.
109.
18±0.
068.
85±0.
06Haro6-28A11.
28±0.
0110.
41±0.
079.
80±0.
041.
77M51B13.
03±0.
0511.
30±0.
0810.
30±0.
05VYTauA10.
15±0.
299.
50±0.
019.
22±0.
180.
38M01B11.
44±0.
3111.
01±0.
0410.
68±0.
23IWTauA10.
21±0.
029.
42±0.
109.
05±0.
040.
83K71B9.
97±0.
029.
32±0.
099.
15±0.
04LkHα332G1A10.
09±0.
039.
18±0.
028.
66±0.
012.
98M11B10.
82±0.
059.
76±0.
049.
31±0.
02LkHα332G2A9.
85±0.
028.
76±0.
048.
34±0.
033.
16K71B10.
70±0.
029.
61±0.
089.
03±0.
05LkHα332A10.
45±0.
059.
09±0.
038.
15±0.
102.
67K71B10.
69±0.
059.
72±0.
069.
37±0.
29Haro6-37A9.
998.
70±0.
068.
15±0.
082.
12K61a11.
7910.
39±0.
069.
70±0.
08B10.
659.
51±0.
068.
97±0.
08UYAurA9.
01±0.
068.
26±0.
077.
42±0.
051.
35K71B11.
20±0.
079.
85±0.
068.
53±0.
05J.
Woitasetal.
:MassratiosofTTauristarcomponents21TableA.
2.
continuedSystemComponentJHKAVSpectraltypeSFRRWAurA8.
66±0.
237.
87±0.
086.
97±0.
190.
53K31B9.
97±0.
278.
95±0.
108.
90±0.
23NTTS155203-2338A7.
67±0.
037.
27±0.
037.
21±0.
010.
2G22B10.
14±0.
089.
57±0.
089.
24±0.
04NTTS155219-2314A10.
66±0.
049.
94±0.
049.
69±0.
040.
2M42B11.
58±0.
0611.
02±0.
0810.
78±0.
08NTTS155808-2219A10.
23±0.
039.
51±0.
039.
29±0.
030.
3M32B10.
81±0.
0410.
11±0.
039.
90±0.
03NTTS155913-2233A9.
31±0.
038.
72±0.
038.
54±0.
020.
2K52B9.
97±0.
049.
32±0.
049.
24±0.
05NTTS160735-1857A10.
27±0.
039.
48±0.
039.
29±0.
041.
1M32B10.
73±0.
0410.
06±0.
059.
71±0.
05NTTS160946-1851A8.
48±0.
037.
84±0.
037.
72±0.
011.
3K02B10.
17±0.
059.
62±0.
069.
28±0.
05RXJ1546.
1-2804A7.
98±0.
018.
01±0.
012B8.
65±0.
028.
39±0.
01RXJ1549.
3-2600A8.
55±0.
018.
43±0.
022B9.
43±0.
019.
19±0.
03RXJ1600.
5-2027A9.
73±0.
019.
46±0.
022B10.
06±0.
029.
89±0.
04RXJ1601.
7-2049A9.
26±0.
019.
08±0.
022B10.
01±0.
029.
65±0.
03RXJ1601.
8-2445A9.
22±0.
028.
87±0.
052B9.
78±0.
039.
89±0.
13RXJ1603.
9-2031BA9.
49±0.
019.
20±0.
022B9.
94±0.
029.
73±0.
04RXJ1604.
3-2130BA10.
24±0.
0110.
08±0.
082B11.
06±0.
0110.
46±0.
11WXChaA10.
22±0.
029.
20±0.
018.
43±0.
032.
14K7-M03B11.
84±0.
0711.
01±0.
0310.
94±0.
30VWChaA9.
22±0.
028.
05±0.
017.
25±0.
032.
39K53B9.
83±0.
038.
96±0.
038.
89±0.
14C≥11.
65≥11.
359.
75±0.
49HMAnonA8.
99±0.
018.
38±0.
018.
11±0.
021.
21G83B10.
71±0.
019.
93±0.
0210.
25±0.
14LkHα332-17A7.
887.
016.
282.
35G23B11.
5810.
8210.
35IKLupA9.
46±0.
098.
71±0.
058.
33±0.
020.
20M04B10.
82±0.
099.
86±0.
059.
43±0.
02HTLupA7.
66±0.
046.
95±0.
026.
55±0.
031.
45K24B10.
399.
728.
96HNLupA9.
90±0.
138.
57±0.
117.
76±0.
062.
30M1.
54B10.
10±0.
139.
07±0.
118.
71±0.
08HBC603A9.
548.
728.
69±0.
100.
79M04B≥12.
43≥11.
619.
77±0.
25HBC604A10.
23±0.
089.
55±0.
059.
18±0.
060.
12M5.
54B11.
5811.
0711.
14HOLupA10.
04±0.
069.
14±0.
068.
60±0.
031.
25M14B11.
1110.
389.
8222J.
Woitasetal.
:MassratiosofTTauristarcomponentsAppendixB:Color-magnitudediagramsJ.
Woitasetal.
:MassratiosofTTauristarcomponents23Fig.
B.
1.
.
ComponentsofWTTSsystemsplacedintoNIRcolor-magnitudediagramstogetherwiththePMSmodelbyD'Antona&Mazzitelli(1998).
Thedashedlinesdenoteevolutionarytracksformassesfrom0.
02to0.
9M⊙,thesolidlinesareisochronesforages7·104,105,2·105,3·105,5·105,7·105,106,2·106,3·106,5·106,7·106,107,2·107,3·107,5·107and108yr(MS).
24J.
Woitasetal.
:MassratiosofTTauristarcomponentsFig.
B.
1.
continuedJ.
Woitasetal.
:MassratiosofTTauristarcomponents25Fig.
B.
1.
continued26J.
Woitasetal.
:MassratiosofTTauristarcomponentsAppendixC:Hertzsprung-RusselldiagramsJ.
Woitasetal.
:MassratiosofTTauristarcomponents27Fig.
C.
1.
ComponentsofTTauribinarysystemsplacedintotheHRDasdescribedinSect.
5.
Thecrossgivesthepositionoftheprimary,thehorizontaldashedlinesgivethelocusforthecompanionandtherespectiveerror.
ThePMSmodelfromBaraeetal.
(1998)isalsoindicated.
Evolutionarytracksareplottedformassesof0.
04,0.
06,0.
08(bold),0.
10,0.
15,0.
20,0.
30,0.
40,0.
50,0.
60,0.
70,0.
80,1.
0and1.
2M⊙,theisochronesdenoteagesof1,2,5,10,20,50and90Myr.
28J.
Woitasetal.
:MassratiosofTTauristarcomponentsFig.
C.
1.
continuedJ.
Woitasetal.
:MassratiosofTTauristarcomponents29Fig.
C.
1.
continued30J.
Woitasetal.
:MassratiosofTTauristarcomponentsFig.
C.
1.
continuedJ.
Woitasetal.
:MassratiosofTTauristarcomponents31Fig.
C.
1.
continued32J.
Woitasetal.
:MassratiosofTTauristarcomponentsFig.
C.
1.
continuedJ.
Woitasetal.
:MassratiosofTTauristarcomponents33Fig.
C.
1.
continued34J.
Woitasetal.
:MassratiosofTTauristarcomponentsFig.
C.
1.
continued