1993ApJS ... 86. .293D the IRTaccountsforabout40%oftotalchromospheric tionships havebeenobservedinotherdiagnostics(e.g.,Simon the Caiiemissionfluxtomagneticdynamobeheved be blue Canfines,theIRTliesin aregionofthespectrumwith losses whichisequivalenttotheHandKlosses.Unlike the which sharetheupperlevelsofHandKtransitions(see, relationship isnowfirmlyestablished,atleastforsinglestars. the solar11yrcycle(Bahúnas&Vaughn1985).Noyesetal. &Fekel 1987;Strassmeieretal.1990)andtherotation-activity (1984, hereafterNHBDV)demonstratedtheconnectionof stellar activitylevelsmayundergocyclicvariationssimilarto for example,Mihalas1978).Duncan(1983)estimated that called Caninfraredtriplet(IRT),XX8498,8542,and8662, operating inrapidlyrotating,convectivestars.Similarrela- ered unevenlywithplagelikeregions(Wilson1978)andthat Wilson projectwenowknowmanystarspossesssurfacescov- chromospheres. ThroughtheremarkableworkofMount H andKlineshaveprovidedawealthofinformationonstellar schild &Eberhard(1913).Subsequently,observationsofthe related toplageregionsontheSun(Hale&Ellerman1903) and connectedtoactivestellarchromospheresbySchwarz- cal AstronomyObservatories,operated bytheAssociationofUniversities Foundation. for ResearchinAstronomy,Inc.,under contractwiththeNationalScience © 1993.TheAmericanAstronomicalSociety.Allrightsreserved.PrintedinU.S.A. The AstrophysicalJournalSupplementSeries,86:293-306,1993May 1 Transitions whicharesimilartotheHandKUnesso Ca nHandKemissionreversalshavebeenshowntobe VisitingAstronomer,KittPeakNational Observatory,NationalOpti- in theinfraredtripletisabouttwicethatofHandKUnes. increased emissionwithdecreasingperiodwhiletheasynchronousbinariesshowabnormallyhighactivitylevels which areknownorsuspectedtobechromosphericaUyactive.Thesampleincludesbothsingleandbinarystarsof Subject headings:infrared:stars—stars:chromosphereslate-type for theirrotationperiods.Severalstarsexhibitrotationallymodulatedemissionwhichisanticorrelatedwiththe rotation period,luminosity,temperature,andduplicityareanalyzed.Synchronousbinariesshowaslighttrendof diagnostics weremeasuredandtheirrelativemeritsarediscussed.Dependenceofchromosphericemissionupon stellar brightness.Finally,estimatesofchromosphericenergylossesarepresentedwiththeresultthattotalloss spectral typesfromF2toM5spanningluminosityclassesIII,IV,andV.Severaldifferentofactivity Spectroscopic observationsoftheCaninfraredtriplet(XX8498,8542,8662)havebeenobtainedfor45stars © American Astronomical Society • Provided by theNASA Astrophysics Data System OBSERVATIONS OFTHECanINFRAREDTRIPLETINCHROMOSPHERICALLYACTIVE Center forExcellenceinInformationSystems,TennesseeStateUniversity,33010thAvenueNorth,Nashville,TN32703 Joint InstituteforLaboratoryAstrophysics,UniversityofColorado,CampusBox440,BoulderCO80309 1. INTRODUCTION Ritter Observatory,TheUniversityofToledo,2801WestBancroft,OH43606 Dyer Observatory,VanderbiltUniversity,Nashville,TN37235 Received 1992August5;acceptedOctober16 SINGLE ANDBINARYSTARS 1 1 Robert C.Dempsey Gregory W.Henry Bernard W.Bopp Douglas S.Hall ABSTRACT AND 293 tions ofawidervarietyobjectswereobtained. ily tobrightstars(V<5).Furthermore,theobjectsinthese tensive numberofstellarobservationstheX8542fine. tron density,andCandensitytobehigherforagivenoptical the emissionresultsfromasteepeningoftemperaturegra- tions andinterpretationsofsolarIRTplageprofileswerepre- that theIRTisformedinlowerchromosphere.Observa- tectors. Calculationofsurfacefluxesisquitestraightforward wavelength regioniseasilyobservablewithmodemCCDde- well-defined continuum,makingcalibrationsimpler.This CVn) classeswhilesomeFK Comae starsareamongthesingle BY Draconis(BYDra),and RSCanumVenaticomm(RS unevolved. Thebinarysystems includemembersoftheAlgol, role oftheIRTinactivechromospherestars,andtogain in- ity levelsasindicatedbyCanHandKfluxes.Toascertain the depth, comparedtothequietphotosphere,thusincreasing dient inthechromosphere.Thisforcestemperature,elec- and Kfines,Vemazza,Avrett,&Loeser(1976)demonstrated stars. Spectraltypesrangefrom F2toM4.5.Inmostcasesonly characteristics includingbeing singleorbinaryandevolved sight intothedynamosoperatingonthesesystems,observa- studies tendedtohavelowrotationalvelocitieswithmildactiv- Linsky etal.(1979)andFoing1989)presentedan ex- source functiontherebyproducingemissioninthefinecores. sented byShine&Linsky(1972,1974)whoconcludedthat for thesefeatures(Linskyetal.1979).AsisthecasewithH 70 starsintheinfrared.Objectsstudiedcoverawiderange of We reporttheresultsofmorethan200observationsover To dateobservationsoftheIRThavebeenrestrictedprimar- 1993ApJS ... 86. .293D 2 tronomy, Inc.,undercontractwith theNationalScienceFoundation. which isoperatedbytheAssociation ofUniversitiesforResearchinAs- from filhnginbychromospheric emission.Spectraofeight ability duetostarspotsorboth.Exceptforafewcases(e.g., HR presence ofstrongCanHandKemission,photometricvari- in Table2.SpectraforthestarsarepresentedFigures 1-4. Stars aresegregatedinto“active”and“inactive”basedon the was usedforIMPeg(Huenemoerder,Ramsey,&Buzasi revealed nosignificantdifferenceswithpreviousresults.There- data withPDM(Stellingwerf1978),asimplementedinIRAF, fore, theephemeris2,444,686.5+\9A\0E(Strassmeieretal. reported previouslyinconjunctionwithspotimaging(Demp- sey etal.1992).Performingstandardperiodanalysisonthe May. ResultsforaGemfromthe1989-1990seasonhavebeen obtained in1989January-MarchandDecember-1990 IM PegwiththeVanderbilt-TennesseeState0.4mAutomatic Photoelectric Telescope(Genetetal.1987).Thedatawere tween 30-100:1andthedatawerereducedinstandardfashion and 8662willbereferredtoasIRT-1,IRT-2,IRT-3,re- lution of1.2Á.Thesignal-to-noise(S/N)wastypicallybe- spectively. using IRAF.Henceforth,thethreetransitions,XX8498,8542, Dispersion Spectrograph(=LDS,Boppetal.1992)withareso- fainter stars.HerethestarswereobservedwithRitterLow 1908) alloftheactivestarsexhibitshallowprofilesresulting included allthreelinesofthetriplet,wereobtained which wasdemonstratedbyShine&Linsky(1974)toshow and activesolarregions.Lowerdispersionobservations,which the greatestchangeincoredepthofthreebetweenquiet ing afiber-fedechelle(seeDempseyetal.1992fordetails). 1990). 1988a) wasadoptedforaGemwhile2,422,243.316+2439E These observationscoveronlytheregionofX8542line resolution wasabout0.2Á.AtRitterObservatorythehighest Table 1.ThehighestresolutionwasobtainedwiththeKPNO spectral resolutionwas0.39Âwiththe1mtelescopeemploy- Coudé FeedwhereaTICCDwasusedwithgratingA.Herethe in 1989.Fourdifferentresolutionswereusedasdetailed National Observatory(KPNO),overa3yrintervalbeginning vatories, RitterObservatoryinToledo,Ohio,andKittPeak Dempsey etal.(1992). photosphere. Manyoftheseobservationswereperformedin localized regionsspatiallyassociatedwithlargespotsinthe phase coveragewassufficienttoidentifytheemissionasdue conjunction withthespectralmappingprogramconductedby one observationperstarwasobtainedbutinseveralcases, 294 2 IRAFisdistributedbyNational OpticalAstronomyObservatories, A fistofobservedstarsandtheirrelevantpropertiesisfound Johnson VandBphotometrywereobtainedforaGem Spectroscopic observationswereobtainedfromtwoobser- © American Astronomical Society • Provided by theNASA Astrophysics Data System 2.1. SpectroscopicObservations 2.2. PhotometricObservations 3. ACTIVITYLEVELS 2. OBSERVATIONS DEMPSEY ETAL. -1 1 -1 -1 be expectedbasedonvsinialone. three IRTlinesareasymmetricandshallowerthanwould phases lacktheemissioncore. changes intheemissioncore (Fig.2).Observationsatother vations separatedbyfourdays, 0.14inphase,revealquick and fivemoreovera1weekinterval in1990May.Twoobser- higher vsini.Twoobservations wereobtainedin1990March comparable tothatinIMPegeventhoughthelatterhas a claims ofphotometricvariabilityforthisstar.However, all depth. AsimilarresultisobservedinHR7635,oDra, and broadening inactivestarspectraandcomparingthe core its spectraltypeandvsin/,thelatterverifiedbyartificially Although itpossessesmoderateemissionintheHandKfines low profilewithemissioncorespresentatseveralphases(Fig. This likelyresultsfromlessrotationalsmearingoftheemission eUMi. (Strassmeier etal.1988b)thedepthofIRT-2isconsistentwith files. NotethesimilarityofV711TauandUXAriinFigure4. owing toVYAri’slowerpsiniof6kms. km s')butwithslightlymorewell-definedemissionreversals. that ofV711Tau(psini=38kms)andUXAri37 broadening alone.NosignificantemissionisdetectediniVir but lookingatartificiallybroadenedspectraofinactiveearly (F6 III)aswefi. G IIIstarssuggestthefinedepthsareconsistentwithrotational in thisprogram.TheIRTfinesappearverystrongandbroad. 5 ).Low-resolutiondataalsodisplayfilled-in,asymmetricpro- An appropriatestandardisnotavailablefordirectcomparison in onaLDSspectrumobtained1990December10(Fig.4). on eightdifferentoccasionsovertheinterval1989January its lowrotationrate(psin/=8kms,P76days).High-res- olution observationsrevealanextremelyshallowIRT-2profile eral objectsfollow. in thisfineapparentADLeo.Specificcommentsaboutsev- which theemissionextendsabovelocalcontinuum.Inall eight casestheemissionwasweakestatIRT-3withnoreversal one observation.TheIRT-1fineofBYDraistheonlycasein fined emissionrisingabovetheshallowfinecore)inatleast adae) revealclearlydefinedemissionreversals(i.e.,wellde- Draconis, ADLeonis,EQVirginis,VYArietis,andXAndrom- stars (V711Tauri,IMPegasi,BMCanumVenaticorum,BY 10-23 (Fig.2).However,thetripletisonlymoderatelyfilled a a 3 Cam.—Strassmeier&Hall(1988)rejectedprevious BM CVn.—ThedegreeoffillinginIRT-2CVn is HR 1908.—Thisisanexampleofamarginallyactivestar. 14 Ari.—WithaspectraltypeofF2IIIthisistheearheststar A HR 454.—Thisstarexhibitsinterestingvariationsdespite V711 Tau.—High-resolutiondatarevealanextremelyshal- V YAri.—TheIRTforthisactivebinarystronglyresembles LDS, grating6R021.28380-8685 Instrument DesignationResolutionWindow Echelle ROl0.398520-8565 Coudé, Camera5,gratingAKP20.238530-8610 Coudé, Camera5,gratingBKP10.908425-8780 DefinedasFWHMofcomparisonlines. Equipment TABLE 1 >H>H^¡
§ § § h) a pit p^ CL, O O Ph tí tí Pu PU tí tí tí tí tí o O O Pu O O O O O Pu PU O PU PU PU O O 0* O « W w tí tí w tí tí tí tí tí tí tí tí tí tí tí tí tí tí tí tí tí Oí tí tí tí tí tí tí tí tí tí tí lOO O)lO OCO lO1-1 m00 OlO CO CO O lO o lO es o o »o esO coO coO LOO 00LO eso LOo o o o loO b-LO coLO esLO esO O OCS r-Hlo iOT^eocoi-iint- tî< CO tîh lO Oco Oco O)^ coes Tji ñ 05 CO °î OO û7 ^ es co oï t- Íh ^ ® eo b-^ oo TÍH CO (kj b~ aÖ g“ : ^ Ti< es es tí* es - «> b- S oo es es oo ® CO ^ O Tí* ^ O I > LO £O > tí tí § p tí + hhhh+hh_ + 3 ;> > 3 S ä o>>HK 3 3 > 3 3 S>>S¿ > > p > > > es lo es co es Ü o es <30 r-i th es es oo lo CS LO 00 LO CO LO b- 1-1 Ü tí tí tí tí Ü ^ O tí tí tí tí tí tí Ü Ü tíÜ¿¿títí tí O Ü tí tí tíOtítítí Ü tí Ü lOLO O 1-1CO Olo b-05 00CO coCO ooTi* i-*T-l eso rio 05co t-05 05o Oco 05Tí* CJ5i-iCSCS05b- r—* 1-1 i—* r-H b-lo ooi—i ooes tíioo Tiioo cooo 05CO 05o loi-* coCS coOS 1 i—*o 1-1 LOlo LOco 05o b-CO lo00 lo00 co05 coTí* b- 05 rH rH CO 1-1 1-1 es es es cs co co co co co <—) Ty tj Li j COCOCOb-t- oo oo oo oo 05 1-105 05I-* OCS OCS CSi-* Q Q Q Q P Q Q Q Q Q P P P P P p p p p p p p p p p p p p p p p p p H W W M W W tí tí P P p W PQ tí tí tí tí tí tí tí tí tí tí tí tí tí tí tí tí tí tí tí tí ^ Ti* co m Ü < m a M s SI LOco loLO mjh* ¿a M M rf t-es «J ió oo ^ 00 00 M ü > S M § M -f- LO LO M U J J V) Ö ^ ftScsgt- 'S o w tí O’ oí > « > p tí tí Cfi > > PU O tí '¡^T' cs i—i i—i cs i-i es cs n CS i—t i—* i—t O O O O O O O O O O O ¡ PU O PU O O O O O O O O O PU CU Ph PU O O Pu PU Pu O tí tí tí tí tí tí tí tí tí tí tí ! tí tí tí tí tí tí tí tí tí tí tí tí tí tí tí tí tí tí tí tí tí tí O_ oLO COo oLO o cso LOo o b-o o Ti*O LO1-1 COo o o loo olo oco oco o COo Oo LOo Ti*o 00o LOo oLO oCS oLO LOo oco o o LOOO b-Tí* I-*LO 00LO COTí* Ti*Tí* LOI-* Tí*Tf LO LOo Tí*oo COi-* tí*LO coTí* ooCO b-•^* t-^ LOn nLO oTí* b-Tí* Tí*co Tí* csCO coLO t-tí* coOO Ti*tí* lo1-1 t-Ti* COO OCO COTí* tí oo i—i e'i o co ^ 2lo co<=> co coP ûT 0 b- lo eo co ¡ P¡ 03 *>■ 2 CO i-* b- b- b- co i co oo \ e^ co lo «^ MS VI /vï'“ oo loC5 esTí* oo : VI ^ ^ VI o : ^ > „ > p > Tí* H LO O LO p w Ü tí tí 1* LO ^ -|- + + TS P > P + P ^ P 5 ^ T > > >>>33 > P P LO ^ « p > P > K P + n rQ o s> CS CSL “r CO LO LO LO QO LO I—* LO CO rH O ¿ Scs rl OS iCS nLO o o es fe tí ^ a bbtí fe b. tí Ü o O fe Ü tí tí tí tí tí ^ <¡ Td tí Ü tí Ü S tí •p 3 COLO Ti* § 3 1-1 O CO o cs 00 Ti* b- 1-1 05 b- b- 05 05 rH OO Ti* 05 „cs lo Q0 „ t- o es n es O co05 esO b-cs Oco coTf* 05es b-n ooTí* coTí* COco CStí* coTí* Tí*oo coCO 05LO cori eo1—lLOCSb-b- co o o 11 ooo otí* oLO °2 ^co ^50 oS 05co eslo b-co b-Tí* LOlo COcs 5 d g « 1-H LO CO 05 b- cs co co b- o ri CS CS CO OO 05 05 cs tí* cob- LO CS cs i L° es T 05 o ¡ CO Ti* b- CO 05 1-1 1-1 1-1 1-1 cs cs cs cs cs cs cs os co co co co tí* co co + 05 *7 + 05 rH ü co ^ p p p p p p p p p p p p p p p p p p p p p P P P P P P P P P p p p p w w P P P P p p p p p p p p p p p p p p p p p p m P ü P P P p p p p ¡ £<2.2 05 a o ^ ^ CO o Ö \-p-xM h 1 P P 8 OJ ^ E 2 -r* p p ^ ^ fe •s a M o 1 H » _i Data are taken from Dempsey et al. 1992, Gray 1989, Hoffleit 1982, Noyes 1984, Speisman & Hawley 1985, Strassmeier 1988b, and 1990. Refers to the cooler component unless hotter is known be source of activity. Q tí ü M ^ C , <í CÏ5 <í ¡^1 o ¡ ^* P P Tí* P Where only one quantity listed for SB2s values refer to the active component while SB Is primary are listed. „ >h tí tí ^ ¡ tí tí b-P H— fe STí* ¿^ ü E <í fe tí p Ü Ü Q ^ H fe tí O’ ° -1 ” VJ. P P Ö , > p p í> i-* fe !> ö eo P Ö CClP O b CCL<Í Ü H Q P Q fe b P American Astronomical Society • Provided by the NASA Astrophysics Data System 1993ApJS ... 86. .293D the otherFKComtypeobject inthissurvey,HD199178. ences observableinthethreeIRT lines.BothIRT-1andIRT-2 by dark,coolspots(Vogt&Penrod1983).However,in the tions. Asymmetriesarepresentinthelinecores,particular units ofintensity.Datahavebeennormalizedtounityandshiftedbothverticallyhorizontallyforclarity. may bepresent.Spectraofthis starareverysimilartothoseof view. Emissioninthewings of thelines,inparticularIRT-1, sphere, thesearelikelytheresultofplagesmovinginandout of case oftheIRT,sincecoresareformedinchromo- changes aresimilartothoseseeninabsorptionlinesproduced IRT-2 andIRT-3,whicharemirroredinbothlines.These sented inFigure6coverslightlylessthanthreecompleterota- of itsclasswhereitisbelievedtobeacoalescedbinary(Bopp & Stencel 1981).Withaperiodof2.4daystheobservations pre- 296 Fig. 1.—High-resolutionspectraofIRT-2forinactivestars.Aprominenttelluriclineisindicatedinthespectrum^Her.They-scale isinarbitrary HD 129333.—Dataforthisstar (Fig.4)indicatethediffer- FK Com.—Thisrapidlyrotatingsinglestaristheprototype © American Astronomical Society • Provided by theNASA Astrophysics Data System Fig. leId Fig. lalb DEMPSEY ETAL. tially filledinbyemissionas seeninFigure8.Theprofiles low-resolution. Thedataonthis starrevealtheIRTtobepar- strongly resemblethesolarplage profilesofIRT-1presentedby tion data. served oneightoccasionsat high-resolutionandtwicewith was observedbyHuenemoerderetal.(1990)withlowerresolu- tions. Asimilarresult,butwithoutthedetectionofreversals, the Flightcurvedisplayedbelow.Thespectracoverthreerota- which roughlycorrespondtophotometricminimaasseen in emission reversalisobservedintwospectra(0=0.35,0.86) ure 7.Atthetopoffigurearespectra,orderedinphase. An This isconsistentwiththeresultsofShine&Linsky(1974). reveal emissionreversalswhileonlyashallowIRT-3isvisible. X And.—Thislong-periodasynchronous systemwasob- IM Peg.—PhasedependentvariationsareillustratedinFig- 1993ApJS ... 86. .293D for BMCVn.Thesetwoobservations wereobtainedfourdaysapart(0.14inphase). Fig. 2.—Sameas1fortheactive stars.Singlearrowsdenotetelluriccontaminationwhiledouble highlightthequickchangeinemission © American Astronomical Society • Provided by theNASA Astrophysics Data System Fig. 2e Fig. 2/ Fig. 2c2d 1993ApJS ... 86. .293D R alsodependsonluminosity.However,remainsanexcel- tometry displayedbelow.Emission isgreatest,i.e.,Rlargest, is plottedinthetopofFigure 10withcontemporaneouspho- residual coreintensityforoGem duringthe1988-1989season that canbedetectedinmoderately activestarslikeoGem.The lent parametertostudysmalltemporalvariations. the finebecomesbroaderandmoreshallow.Toalesserextent, pendent inthatRincreasesastherotationratesince no apparentvariationsatthislevel.NotethatRisvsin/-de- Lambert 1987;butseeAyers,Fleming,&Schmitt1991),show and aBoo,whichsomehaveclaimedtobemildlyactive,(e.g., ent thattheinternalerrorsareabout2%.Evenstarslikee Peg better results.Hereerrorsprimarilyresultfromcontinuum stars, whereanumberofobservationsareavailable,itisappar- placement ifS/Nissufficientinthefinecore.Forstandard tion. onstrated howtheresidualcoredepth(R)couldbeusedwith must beusedwithcautionduetoluminosity,metalficityand to difficultiesindefiningthecontinuumandfinewings, v sinieffects.Bothmethodssufferfromtelluriccontamina- making smallvariationsundetectable,whileintegratedindices c c c c in Linskyetal.(1979),anindexobtainedbyintegratingthe the star?Frequently,investigatorsuseequivalentwidth area underthefinecontainedinalimitedbandpass.However, W measurementsaretypicallyonlyaccurateto5%-10%due ( ofaspectralfeaturetoquantifythelevelactivityor,as ered withsuchregions.AsimilarresultwasfoundbyBaliunas c sess strongemissionreversalsinallthreeIRTfines. degree offillingsuggeststhatthephotosphereisheavilycov- & Dupree(1982)studyingUVemissioninXAnd. of discreteplagescrossingtheobserver’slinesightwhile Shine &Linsky(1972).Theobservedvariationsaresuggestive 298 x Figure 9isanillustrationofthe smallchangesincoredepth Herbig (1985)andBopp,Dempsey,&Maniak(1988)dem- The firstquestionis,howdoweevaluatetheactivitylevelof BY Dra.—AlongwithADLeoandDFUMa,Drapos- © American Astronomical Society • Provided by theNASA Astrophysics Data System 3.1. CoreDepth wavelength (angstroms) Fig. 2g DEMPSEY ETAL. Fig. 2—Continued rotation, itisusuallynotwell-known owingtouncertaintiesin the strongcorrelationofstellar radiusonperiod(Rengarajan tions ofsurfacefluxwithrotational periodareobserveddueto the fluxtobolometric(Rutten&Schrijver1987; the temperature(T)dependenceintroducedbynormalizing velocity mayrepresentamore fundamentalmeasureofthe liland 1985;Simon&Fekel1987).Forbinaries,falsecorrela- vective turnovertimesarenotwellknownformanystars(Gil- Young etal.1989).Afurthercomplicationresultsinthatcon- gued thatthisisfortuitousandusingRonlypartiallyremoves the scatterintheirflux-periodplots.However,othershave ar- & Yerma1983;Dempseyet al.1993).Whiletheequatorial many dynamotheories.NHBDVadoptedRsinceitreduced convective turnovertimeandisafundamentalparameter in The Rossbynumberistheratioofrotationalperiodto the Thurman 1989;Simon&Fekel1987;Strassmeieretal.1990). Walter 1987;Glebocki&Stawikoski1988;Young,Ajir, & fluxes orluminositiesversustherotationperiodRossby number, R(Barden1985;Basri1987;Basri,Laurent,& reported fortwoseasonsofobservationsbyBoppetal.(1988). changes mirrorthoseofthespots.AsimilarchangeatHawas regions moreuniformlydistributedonthesurface.These emission, whichalsohasthesamemeanlevel,isproducedby decreased from0.10to0.06mag19891990whilethe mean brightnessremainedunchanged.Thisindicatesthatthe anticorrelation foroGem.Duringthisinterval,Rremained eff nearly constantat0.49.Thephotometricamplitude,AF,also 0 gions, assumedtobeplages,arecospatialwiththedarkspots straight forwardinthe1989-1990data(compareFigs.9and producing thebrightnessvariations.Similarresultshavebeen at photometricminimum.Thisindicatesthattheemittingre- Huenemoerder etal.1990).However,thecorrelationisless observed inothersystems(e.g.,Baliunas&Dupree1982; 0 0 15 inDempseyetal.1992). c Since theworkofNHBDVithasbeencustomarytoplot However, duringthe1989-1990seasonthereisnoobvious wavelength (angstroms) 3.2. Fluxes Fig. 2h 1993ApJS ... 86. .293D © American Astronomical Society • Provided by theNASA Astrophysics Data System Fig. 3c Fig. 3a Fig. 3.—Sameas1butforstars withthelow-dispersionspectra Fig. 3e wavelength (angstroms) Fig. 3d Fig. 3b 1993ApJS ... 86. .293D © American Astronomical Society • Provided by theNASA Astrophysics Data System Fig. 4.—Sameas3butforthe activestars.TheIRT-1profileforHD199178islikelycontaminated withnoise. Fig. 4e Fig. 4a wavelength (angstroms) Fig. 4/ Fig. 4b 1993ApJS ... 86. .293D © American Astronomical Society • Provided by theNASA Astrophysics Data System Fig. 4—Continued wavelength (angstroms) wavelength (angstroms) Fig. 4h Fig. 4/ Fig. 4g Ca nINFRAREDTRIPLET tions. Notethechangesinline cores observableinallthreelines,espe- ( 1976)ephemeris. cially atphases0.30and0.71.Phases werecalculatedfromChugainov’s the stellarinclination.Therefore,toinvestigateperiod-activity tively. Linskyetal.(1979)concludedthatemissionwithin width underihtlinecorein2.0and1.0Ábandpasses,respec- broadened tothesamevsiniasactivestar.Photospheric third quantity,Z>,istheequivalentwidthofresidualemis- measured. Thefirsttwo,andW,aretheequivalent believed duetothechangingaspectofspotsorplagesasstar relations wechosetouseonlytheperiod,PPeriods,taken cover 400days. sion outsideofthisrangemayarisefromthephotosphere.The rotates. from theliteratureandlistedinTable2,arederivedviaphoto- sion afterthesubtractionofasuitablestandardwhichhasbeen metric orCanHandKmodulationwherethevariationis ± 1.0Âofthefinecoreischromosphericinoriginwhileemis- x xx Fig. 6.—Low-resolutionspectraof FKCom.Datacoverthreerota- To parameterizetheemissionlevelsthreequantitieswere Fig. 5.—ObservationsofV711Tauatthreephases.Theseobservations 301 1993ApJS ... 86. .293D due toincompletescatteredlightsubtraction. TheCanlineisnotaffected. have improvedconsiderablyinthelast23years,thoseofCar- Linsky etal.(1979).Althoughmodelatmospherecalculations widths wereconvertedtofluxesandusingtheatmo- D couldnotbemeasuredforallprogramstars.Equivalent sphere modelsofCarbon&Gingerich(1969)asdetailedin ment. Duetolimitedavailabilityofappropriatestandardstars, mated tobe10%,duemainlythechoiceofcontinuumplace- mospheric emission.Errorsintheequivalentwidthsareesti- (Schrijver 1987)butassumesthatthestandardhasnochro- pheric fluxwhileimplicitlyremovingthebasalcomponent This quantityhastheadvantageofmeasuringallchromos- ( seeFig.4,Linskyetal.1979)andisignoredincalculatingD. as broadwingsinadditiontothechromosphericemissioncore emission, ifpresent,willbevisibleinthedifferentialspectrum x 302 x Fig. 8.—ObservationsofXandshowing thechangesinplagelikecore.Inbottomspectrum, continuumredwardoftheIRT-2appearsnoisier © American Astronomical Society • Provided by theNASA Astrophysics Data System Fig. lalb Fig. 7.—(a)IRT-2spectraofIMPegorderedinphase,(b)LightcurveforPeg. DEMPSEY ETAL. r lated asarethefluxesintwobandpasses.Therefore,further IRT-2 revealsthatthefluxesinallthreeUnesarehighlycorre- IRT-1 versusIRT-2,IRT-2IRT-3,and7mversus^f° spectra consistofallthreelinesthetriplet.Plotting^for the cooleststars.Totalerrorsinderivedfluxesareesti- gerich (1969)forr<4000K,fluxeswerenotcalculated temperature willchangethefluxbyapproximately8%.Since mated tobe20%-30%. appropriate atmosphereswerenotpresentedinCarbon&Gin- taken eitherfromStrassmeieretal.(1990)orestimated temperatures inoursampletheinfrared.Temperatureswere bon &Gingericharetheonlyonesavailableforrangeof spectral typesusingthesamemethod.Anerrorof100Kin eff Except fortheRitterechelledata,whichcoveronlyIRT-2, Vol. 86 1993ApJS ... 86. .293D 1988-1989 observingseason. and dwereplottedversusperiod(Figs.1113).Thereisa between IRT-1-IRT-2,especiallywhenthechromospheric line becomesalmostcompletelyfilledinforthemostactive tors. Amongthefluxes,thereishighestdegreeofscatter the conclusionsaresimilarforothertwolines.Similarre- is toosmalltoincludethemajorityofchromosphericemis- The largerscatterresultsfromthefactthat1.0Abandpass discussion willberestrictedtoIRT-2butitnotedthat emission fluxislarge.ThisresultsbecausetheshallowIRT-1 Foing etal.(1989)becausemostoftheirstarswereslowrota- sion formostofthestarsstudiedhere.Itwassufficient sults, butwithahigherdegreeofscatter,areobservedin^. stars, makingidentificationofthelinedifficult. (1992) forthecorrespondinglightcurve. while thesolidlinerepresentsphase0.41.SeeFig.15inDempseyetal. ing the1989-1990observingseason.Plusescorrespondtophase0.11, No. 1,1993 x Fig. 10.—(a)RofIRT-2fora Gem. AlargerRindicatesincreasedemission.(6)Contemporaneous lightcurvefor