19 92Apjs. . .79. .255K the Astrophysical Journal

Home , NGC 3077, NGC 3147, NGC 3245, NGC 3310, NGC 4262, NGC 4449

19 92ApJS. . .79. .255K be avaluableresourceforotherapplications,including the X-ray surveys,andavarietyofrudimentaryspectralsynthesis agreement withtheNationalScience Foundation. Universities forResearchinAstronomy, Inc.(AURA),undercooperative scopic identificationofobjectsdetectedinradio,infrared, and spectroscopic classificationofhigh-redshiftgalaxies,spectro- quality spectra,withsufficientresolutionandsignal-to-noise cal AstronomicalObservatories,which areoperatedbytheAssociationof ratio toisolatetheprimarystellarabsorptionfeatures,would more distantgalaxies,whicharemadewithprojectedaperture the spectraofnuclearregionsnearbygalaxiesareavail- galaxies (Wells1972;Dressier&Gunn1982;Gallagher,Bus- Kennicutt (1992,hereafterPaperI). sizes ofseveralkiloparsecsormore. able, thesecannotbedirectlycomparedtotheobservationsof house, &Hunter1989;Silva1991).Whileabundantdataon tively fewcomparableobservationsareavailablefornearby grated spectraofnearbygalaxies,andthisapproachwas for 80spiral,irregular,andpeculiargalaxies,arepresented in ple withpublisheddataforhigh-redshiftsystems.Thefirst re- reviews byDressier&Gunn1990andElfis1990),butrela- ( 1959).Todayintegratedspectraprovideourprimarysource sults ofthisanalysis,includingemission-linemeasurements tra, asdiagnosticsoftheirstarformationratesandionization tematic behaviorofthenebularemissionlinesingalaxyspec- of informationonthepropertiesverydistantgalaxies(e.g., Mayall (1957),Morgan(1959),and&Osterbrock systematized inthefamousseriesofpapersbyMorgan& vided someofthefirstsystematicinformationoninte- vations byHubble(1926)andHumason(1931,1936)pro- mechanisms, andtocomparethepropertiesofthisnearbysam- galaxies. Themaingoalsofthissurveyaretomeasurethesys- of itsstellarcontentandevolutionaryproperties.Earlyobser- spectrophotometry foralargeanddiversesampleofnearby © 1992.TheAmericanAstronomicalSociety.Allrightsreserved.PrintedinU.S.A. The AstrophysicalJournalSupplementSeries,79:255-284,1992April 1 During thecourseofthisstudyitbecameapparentthathigh- The integratedspectrumofagalaxyispowerfuldiagnostic VisitingAstronomer,KittPeakNational Observatory,NationalOpti- To addressthisproblemIhaveobtainedtrulyintegrated galaxies arediscussed. to-noise ratiotomeasuretheprominentemissionandabsorptionfeatures.Thespectrahavebeenreduceda Subject headings:atlases—galaxies:photometrystellarcontenttechniques:spectroscopic spectral types.Adigitalversionofthedataisalsoavailable.Thegeneralcharacteristicsintegratedspectra common spectrophotometricscaleandarepresentedasaseriesofplots,arrangedaccordingtomorphological atlas. Mostobservationscoverthespectralrange3650-7100A,witharesolutionof5-8Â,andsufficientsignal- Integrated spectraof55nearbynormalandpeculiargalaxieshavebeencompiledintoaspectrophotometric © American Astronomical Society • Provided by theNASA Astrophysics Data System 1. INTRODUCTION A SPECTROPHOTOMETRICATLASOFGALAXIES Steward Observatory,UniversityofArizona,Tucson,AZ85721 Received 1991July29;acceptedSeptember11 Robert C.Kennicutt,Jr. ABSTRACT 255 galaxies, butthespectralresolutionofthesedatawasinsuffi- telescope. were obtainedfor44galaxiesin1989-1991,usingalong-slit types ofpeculiargalaxies.Mostthediscussioninthispaper best spectrafromthesurveyintothisspectrophotometricatlas long slitwasused,andthegalaxy imagesweretrailedacrossa drift scanningtechniqueontheStewardObservatory2.3 m sion features.Subsequentlyhigherresolution(5-7Ä)data cient foraccuratemeasurementsofweakabsorptionoremis- energy distributionsandemission-linefluxesforalargeset of tional Observatory(KPNO).Thisprovidedcontinuum con Scanner(1RS)onthe0.92mtelescopeatKittPeak Na- tained for70galaxiesin1985-1987,usingtheIntensifiedReti- tions, reductions,andspectrophotometricaccuracyofthedata to morphologicalandspectroscopictypes(§3).Eachfigureis Á range,mostatresolutionsof5-8Á,andgroupedaccording 2.3 mtelescope.Inorderto observe verylargegalaxies(D= (§3.5). and futurepapers.Otherpartsofthepaperdiscussobserva- is qualitative,withquantitativeanalysesdeferredtoPaperI erties oftheindividualgalaxies,andmaintrendswhichare accompanied byabriefdiscussionofthegeneralspectralprop- available intheliterature.ConsequentlyIhavecompiled adequately representedbythefragmentarydatawhichare applications. Thedatafromthissurveyrevealarichvarietyof & Chivens(B&C)Spectrograph ontheStewardObservatory moderate-resolution (15-25Ä)spectrophotometrywasob- (§2), andhowadigitalversionofthedatamaybeobtained observed alongtheHubblesequenceandbetweendifferent spectra of55normalandpeculiargalaxiesoverthe3650-7100 of galaxies. spectral propertiesamongnearbygalaxies,whichcannotbe 1 '-14')whilemaintaininghigh spectralresolution,anarrow Most ofthespectrainthisatlas wereobtainedwiththeBoiler The surveywascarriedoutintwostages.Large-aperture, The mainpartofthispaperisasetfigureswhichdisplay 2.1. High-ResolutionSpectra 2. OBSERVATIONS 19 92ApJS. . .79. .255K trophotometry wascalibrated usingobservationsofstandard to definetheaperturesandsky backgroundregions.Thespec- teractively, byusingtheobserved intensityprofilealongtheslit than 1%(~0.3%afteralinearfitalongtheslit)werediscarded. tated bythelowsurfacebrightnessofgalaxieswhen ob- pointings, withtheslitoriented alongthedirectionofatmo- Cosmic-ray eventswereremovedintwosteps,firstwith an exposures wereobtained,andregionswhichdeviatedbymore tra extractedwithdifferentsizeaperturesindicatesthatthe within theaperturewereweightedequallyinintegrated were selectedtocontainmostoftheintegratedluminosity stars fromMasseyetal.(1988). Starswereobservedinfixed sidual eventsbyhand. automated sigma-rejectionroutine,followedbyremovalof re- served indrift-scannedmode.Separatedomeandskyflat-field response calibrationandcosmic-rayremoval,stepsnecessi- IRAF softwarepackage.Specialcarewastakenintheflat-field data forsomeapplications. data herecloselyapproximatetheintegratedspectra,but were oftenexcludedfromtheaperture.Comparisonsofspec- the galaxies{AID=0.5-1),whileexcludingcontamination the slit)inperpendiculardirection.Theaperturelimits the slitintooneormoreone-dimensionalsky-subtractedspec- trum actuallyisafineintegraloftheluminositydistribution, slight undersamplingmayinfluencetheinterpretationof spectrum, theveryfaintouterregions(/¿g~24andfainter) drift scaninonedirection,andthesummationlimits(along rectangular aperture,withdimensionssetbythelengthof tra. Eachoftheseisequivalenttoafixedobservationwith exposure, however,eachpixelofthistwo-dimensionalspec- tion. Severallarger,inchnedgalaxiesweremeasuredbyalign- trum. A600gpmgratingblazedat3568coveredthe3650- from brightforegroundstars.Althoughallpartsofthegalaxy formation islost.Consequentlythedataweresummedalong averaged alongthescandirection,andmostdirectspatialin- readout noiseinallcases. least 4times,tominimizeerrorsduesmallvariationsindrift drift rateswereadjustedsothattheimagecrossedslitat along themajoraxis.Thescanlengthswere45"-800",and tra for41oftheseareincludedintheatlas. A totalof44galaxieswereobservedwiththissetup,andspec- ning) alongtheslit.Sincetelescopewasdriftedduring speed ortransparency.Integrationtimeswere20-60minutes. ing theslitwithminoraxis,anddriftscanningtelescope served, inordertoprovideadequatecoverageforskysubtrac- The usableslitlengthfortheobservationswasapproximately slit yieldedaresolutionof4.5Aintheblueand7Àred. 4200 Âblockingfilter)coveredthe4950-7150region.A2''5 Two gratingsettingswereusedtocoverthefullvisiblespec- TI CCD,whichwasUV-floodedforenhancedblueresponse. the skywasdefinedbylengthsofslitanddriftscan. Shot noisefromtheskybackgrounddominatedoverCCD long slitseveraltimesduringeachintegration.Thespectral resolution wasdictatedbytheslitwidth,whileapertureon 3Í5; galaxieswithdiametersalongtheslitof<2i5wereob- 5150 Äregion,anda400gpmgratingblazedat7500Á(with 256 25 One-dimensional spectraforthegalaxieswereextractedin- Data reductionfollowedstandardtechniques,usingthe The B&Cspectrographwasusedwithathinned800X Each CCDobservationcontained130pixels(1"6afterbin- © American Astronomical Society • Provided by theNASA Astrophysics Data System KENNICUTT and quartzlamps,spectrophotometric standardsfromthe spectrum. positions (pairs)werecombined toyieldapseudo-integrated alternated withpairsofskyobservations. Observationsatthree made innebularmode,i.e.,withbothaperturesontheobject, including onepublishedhere(NGC5866),observationswere refers tothecentral45"region.Forafewverylargegalaxies, galaxies shownhere.Afewofthehavediameters con- diameters lessthan45",includingmostoftheemission-fine siderably largerthantheaperture,andspectrumshown metric ornear-photometricconditions. strengths oftheemissionfines.Thedataweretakeninphoto- tions, butinafewcases(Mrk158,Mrk201,NGC3303)the utes, dependingonthebrightnessofgalaxyandrelative computer control.Totalintegrationtimeswere4-180min- nating apertures,withthebeam-switchingperformedunder prove thesignal-to-noiseratioinblue. low- andintermediate-dispersiondatawerecombinedtoim- cally 9-13Á),andhighersensitivityshortwardof4000Â. tained forapproximatelyhalfoftheprogramgalaxies,usinga to 25Áforuniformilluminationofthe45"apertures.The Most ofthespectrashownherearelow-dispersionobserva- CuS0 filter.Thisprovidedsomewhatbetterresolution(typi- 400 gpmgratingblazedat8000Áinsecondorderbehinda Additional observationsintheblue(3600-5500Â)wereob- blazed at5500ÀwithaWG-360UV-blockingfilter,which are fixedpointedmeasurements,madewithapairof45?5 large entranceapertures.Alloftheobservationsreportedhere bination ofacompactimagescaleandfastcamera,which the 1RSspectrometeronKPNONo.20.92mtelescope actual resolutionformostofthedatais15-20ÀFWHM. FWHM forapointsource(suchasanemissionfinenucleus) luminosity distributionsofthegalaxies,rangingfrom12Â large apertures,thespectralresolutionwasmodulatedby provided photometriccoverageover3700-6900Á.Withthe west line.Thegalaxieswereobservedusinga500gpmgrating circular apertures,withcentersseparatedby61"2onaneast- make itpossibletoobtainmoderate-resolutionspectrawith in theatlas. (f/7.5 focus).Thelowerresolutionofthesedata(10-25Â) makes themlessusefulforgeneralapplications,butspectra 70 galaxiesduringthreeobservingrunsin1987-1989,using longward of5100Áarepossible.Thisleveluncertaintyis by normalizingthemeancontinuumintensitiesin4950- Errors of~5%inthefluxscalebetweenregionsshortwardand be animportantconsiderationforapplicationswhichrequire spheric dispersion.Theblueandredspectraweretiedtogether accuracy ofthespectrophotometryisdiscussedindetail the continuumshapetobeaccuratelydetermined.Theoverall §2.3. unimportant foralloftheapplicationsinthispaper,butitmay 5150 Âoverlapregion,orinthe[Om]A5007emissionline. 4 14 galaxies,mostlystrongemission-lineareincluded The spectrawerecalibrated using observationsofHeNeAr True integratedspectrawereonlyobtainedforgalaxieswith Each observationconsistedofaseriesintegrationsinalter- The 1RSisadual-beamspectrometer,withanunusualcom- Spectra coveringtherange3650-6900Âwereobtainedfor 2.2. Low-ResolutionSpectra Vol. 79 19 92ApJS. . .79. .255K wavelength-dependent atmospheric seeing,introducedbe- in E/S0galaxies(e.g.,Kormendy &Djorgovski1989),but be redder(cf.Fig.2).Again,partofthedifferencemay be a whole, includingasystematictendencyforthe1RSspectra to well, butdeviationsofupto±10%arepresent.Similarresid- 2.3 mspectraaresubjecttosmall errors(<10%level)dueto much appearstobeinstrumental inorigin.Inparticularthe real apertureeffect,causedby thewell-knowncolorgradients uals, rangingfrom±7%-15%,arefoundforthesample as a trum isshifteddownby0.2forclarity.Thetwospectramatch spectra arenormalizedtounityat5500À,andthe1RSspec- spectra oftheComaellipticalNGC4889,observedwith the intercomparison ofthesedataprovidesanotherusefulcheck wavelength range.Theinternaltestsdiscussedbelow,however, tions ofupto10%,especiallyinthered.Somedifference 2.3 m{solidline)and0.92{dottedtelescopes. The on thespectrophotometry.Figure2showsacomparison of current observations. suggest thatmostoftheresidualsareduetouncertaintiesin elliptical galaxiesoftendifferatthe10%-20%leveloverthis Oke (1971)foundthattheenergydistributionsofindividual where Cisthefluxat5500À.Theagreementforbothtele- may arisebecausedifferentgalaxieswereobserved;Schild& scopes isquitegood,thoughbothsetsofspectrashowdevia- trophotometry. Theuniformityinspectralresponseoverthe grams withintheIRAFpackageforfluxcalibration.Special techniques, usingtheon-linemountainprogramsforflat-field- the normalizedmagnitudeAB,definedas with eachinstrument,andcomparedthelarge-aperture the data. large apertureswascheckedbydividingflat-fieldexposures ing andwavelengthcalibration,thespectralreductionpro- 1RS standardstarcatalog.Datareductionsfollowed ( 1971).Figure1showsthiscomparison.Theordinate less precise.Severaltestsweremadetoassessthereliabilityof but thegalaxyspectra,derivedwithmuchlargerapertures,are dard starsfromthemeancalibrationwereafewpercentorless, uncertainties inthespectrophotometriccalibration,flatfield- in theenergydistributions,asdiscussedbelow. Carder 1986),whichmayintroduceerrorsofseveralpercent nels, causedbyscatteredfightinthe1RS(Barnes,Massey,& error isasmalllevelofcrosstalkbetweenthetworeticonchan- apertures matchedthatobtainedwithsmalleratthe These testsconfirmedthatthespectralresponseusing45" dard starplacedatvariouspositionswithinthelargeaperture. care wastakentochecktheaccuracyoflarge-aperturespec- scanner observationsbySchild&Oke(1971)andWhitford spectrum wascomputedfortheellipticalgalaxiesobserved ing, andskysubtraction.Typicalresidualsofindividualstan- obtained withdifferentaperturesizes,andbyobservingastan- V 1% level.Probablythemostimportantsourceofsystematic No. 2,1992 Several galaxieswereobservedwithbothinstruments,and As anexternalcheckonthespectrophotometry,amean The photometricerrorsinthesespectraaredominatedby © American Astronomical Society • Provided by theNASA Astrophysics Data System 2.3. SpectrophotometricAccuracy AB =—2.5logX+C,(1) V SPECTROPHOTOMETRIC ATLASOFGALAXIES -1 by theauthor.Columns(4) and(5)fisttheredshift tions), withoutacarefulconsiderationofthelimitationsdis- tion ofX-corrections,detectionlow-levelbluestellarpopula- where preciseenergydistributionsarecrucial(e.g.,computa- from thecatalogsfistedabove, andassumingaHubblecon- corrected absolutebluemagnitude, withphotometrytaken logical type,taken(inorderofprecedence)fromtheRevised to smallirregularitiesintheflatnessofCCDdetectoron tral featureinthegalaxyfallsnearabrightnightskyfine.Due producibility, withaccuraciesofafewpercent.Twospecial cussed above. least 2-3timessmaller.Thisaccuracyisadequateformost deviations averagedovertheentirespectrumareusuallyat regions, withoccasionalerrorsaslarge±15%.Thesevalues stant =75kmsMpc. Column(6)givesthetelescope Vaucouleurs, &Corwin1976), Huchra(1977),orasclassified ond ReferenceCatalogofBrightGalaxies(deVaucouleurs, de about theobservations.Columns(1)and(2)givegalaxy arranged inorderofpresentation,alongwithinformation is showninFigure3. fines isneverperfect,andresidualfeaturesofafewpercentare point-spread functionalongtheslit,subtractionofstrongsky this effect.Anotherproblemoccasionallyoccurswhenaspec- usually notaproblemforthe2.3mdata,whichcomprisemost resolution andsignal-to-noiseratioofthespectrum.Thisis applications, butthesedataarenotrecommendedforcases represent themaximumerrorsinanygivenspectrum;rms cal uncertaintiesof±10%peak-to-peakoverlargewavelength Shapley-Ames Catalog(Sandage&Tammann1981),the Sec- spectrum appears,respectively.Column(3)givesthemorpho- name andthenumberoffigureorfiguresinwhich the of thenightskyspectrum(withbothfullandexpandedscales) an aidinidentifyingsuchartifactsthegalaxyspectra,aplot feature, suchasNaDatlowredshift,orH7nearHgX4358.As common. Thisisaproblemonlyiftheartifactfallsnearreal served withthe1RS.SeePaperIforacompletediscussionof of thisatlas,butblendingmayaffectafewthegalaxiesob- ability oftherespectivefeaturesisaverystrongfunction such aswithHßandthehigherorderBalmerfines,detect- and emissionfeaturesofcomparablestrengtharesuperposed, situations meritabriefmention,however.Whenabsorption apply acorrection. 2.3 mspectrograph,whichintroducesslightvariationsinthe tions relativetothestandardstars,insamedirectionas with theslitorientedalongparallacticangle).Accordingto the standardstarswereobservedinfixedpointings(always cause thegalaxiesweredrift-scannedacrossa2''5slit,whereas and varieswiththeseeingitself,noattempthasbeenmadeto observed inFigures1and2.Sincethesizeofeffectissmall percent inthecalibrationofdrift-scannedgalaxyobserva- Kitt Peakthiswillintroduceanartificialgradientofafew Woolf (1982),theseeingdiskat7100Âisroughly12.5% smaller thanat3650Á,andundertypicalseeingconditions Table 1fiststhebasicpropertiesofgalaxiesinatlas, These testsindicatethattheenergydistributionshavetypi- Measurements oflocalspectralfeaturesshowexcellentre- 3. THESPECTRALATLAS 3.1. GalaxySample 257 19 92ApJS. . .79. .255K plete setofspectraltypesobserved innearbyanddistantgalax- devoted totheseobjects.Aneffort wasmadetoincludeacom- ties, andforthesereasonsaconsiderable portionoftheatlasis liar galaxiesalsopossessaverylargerangeofspectralproper- veys ofradio,infrared,orX-rayluminoussources.Thepecu- higher frequencyinsurveysofhigh-redshiftobjects,or sur- spectral classesaremissinghere, Iwasabletofindlocalanalogs ies. Althoughitisquitepossible thatsomeextremelypeculiar few percentofthelocalpopulation,theyappearwithmuch peculiar galaxies.Althoughgalaxiescompriseonly a bers forarectangularscan(east-westbynorth-south).Special notes orremarksareindicatedincolumn(8). eter, withasinglevalueforcircularaperture,andtwonum- used intheobservation,andcolumn(7)listsaperturediam- Oke (1971;opensquares)andWhitfordcircles).SeetextfordefinitionofthenormalizedfluxAB(v). 258 The atlasisdividedroughlyequallybetweennormaland Fig. 1.—Comparisonofmeanspectragiantellipticalgalaxiesobservedhere(solidlines)withspectrophotometricscannerobservations bySchild& © American Astronomical Society • Provided by theNASA Astrophysics Data System KENNICUTT groupings werecarefullyselected withthisinmind.Foreach type andtoseesubtledifferences betweenthespectra.The while conservingspace.This hastheadditionaladvantageof figure anaccompanyingdescription isgivenin§3.3,andI making itmucheasiertocompare spectraofagivengalaxy sented acompromisebetweenretainingthemaximumdetail Figures 5-22.Thespectraaregroupedfourtoapage;thisrepre- to essentiallyeverytypeofspectrumobservedinpublished found inPaperI. cerning theselectioncriteriaandsourcesforsamplemay be surveys ofhigh-redshiftoractivegalaxies.Moredetailscon- The spectraforthe55galaxiesinatlasarepresented in 3.2. PresentationoftheSpectra Vol. 79 19 92ApJS. . .79. .255K telescope (solidline),andbylarge-aperturespectrophotometryontheKPNO0.92m(dottedline).Thespectrahavebeenshifted by0.2fluxunits ies wereobservedathighGalacticlatitude,whereforeground within thegalaxiesthemselves.Thevastmajorityofgalax- for clarity. corrected forforegroundGalacticreddeningor corrected foratmosphericextinction,buthavenotbeen normalized tounityat5500Á.Thespectrahavebeen ies. Theintensitiesareplottedasfluxperunitwavelength, expanded spectraintheblue(3600-5400Á)forselectedgalax- the spectrathemselves. recommend thatthereaderconsultthistextwhileexamining same spectrumexpandedbyafactor of10inintensity. 3500-7200 Á,exceptforFigures12,14,and18,whichshow No. 2,1992 Fig. 2.—ComparisonofintegratedspectratheComaclustergiantellipticalNGC4889,obtainedbydriftscanswithStewardObservatory 2.3m All spectraareplottedonacommonwavelengthscaleof Fig. 3.—Atypicalnightskyspectrum atKittPeak.Thelowerplotshowsthefullnightskyspectrum,normalized tounityat5500Â.Thetopplotisthe © American Astronomical Society • Provided by theNASA Astrophysics Data System SPECTROPHOTOMETRIC ATLASOFGALAXIES length andsmoothedwitha46.5Asquarefilterforthe2.3 and 0.92mdata,respectively.Forclarityofpresentation,resid- of emissionUnefluxesandequivalentwidthsforthegalaxies. emission linesshouldonlybetakenasaqualitativeindication of therelativeUnestrengths.PaperIcontainscompletelistings either sideof5120Âinthe2.3mdata),heights tions, mostnotablyNGC1569(è=11°)inFiguresand19. slightly withwavelength(andchangesbyafactorof1.5on It isimportanttonotethatsincethespectralresolutionvaries reddening islikelytobenegligible,butthereareafewexcep- Prior toplotting,mostofthespectrawererebinnedinwave- 259 19 92ApJS. . .79. .255K (20). Seyfert2nucleus.(21)NGC 5283. (22)LocatedinPerseuscluster,doubleemission-linesystem. (23)Mrk430.(24)201. interacting ormerginggalaxy.(5) Spectrum shapeaffectedbyhighGalacticforegroundreddening.(6) Driftscanorientedwithmajoraxis.(7)Haro9.(8) Haro 3.(17)NGC4861;aperturecentered ongiantHnregion.(18)NGC2366;aperturecentered Hnregion(NGC2363).(19)Seyfert1nucleus. M82. (9)Mrk271.(10)297. (11) MemberofAbell1367cluster.(12)Starburstnucleus.(13)Mrk 158.(14)Mrk691.(15)538.(16)NGC3353; NGC 2775. NGC 1357. NGC 3941. NGC 3245. NGC 4889. NGC 4648. NGC 4472. NGC 3379. NGC 2276. NGC 4750. NGC 3147. NGC 1832. NGC 3623. NGC 3368. NGC 5866. NGC 4262. NGC 5195. NGC 3077. NGC 4670. NGC 4485. NGC 4449. NGC 1569. NGC 6643. NGC 6181. NGC 4631. NGC 2903. NGC 6217. NGC 5248. NGC 4775. NGC 3627. NGC 5996. NGC 3471. NGC 3690. NGC 3310. NGC 6240. NGC 3034. NGC 6764. NGC 7714. NGC 2798. UGC 6697 NGC 6052. NGC 4194. NGC 3303. NGC 1275. Mkr 3 NGC 3227. NGC 7469. NGC 5548. NGC 3516. Mrk 487... Mrk 71.... Mrk 59 Mrk 35— NGC 3921. Mkr 270... Notes.—( 1)VirgoClustermember. (2)Comaclustermember.(3)Observedinnebularmode;aperture valuesrefertomajorandminoraxes.(4)Strongly Name (1) © American Astronomical Society • Provided by theNASA Astrophysics Data System Figure(s) 22 21 21 21 20 20 20 22 22 22 21 14, 15 11 11, 12 11, 18 10, 12 10 10 10 17, 18 16 16 16 16, 18 14, 15 14, 15 14, 15 11 19 19 19 17 17 17 19 9 6 6 6 6 9 9 9, 18 7 7 7, 12 7 5 5 8, 12 8 8 8 5 5 (2) E3 El/SO E0 Sa SO SB0 SBO/a SO E4 Sc Sb pec Sb SBb Sa Sab Sa 10 SB pec Sm/Im Sm/Im Sm/Im Sc Sc Sc Sc SBbc Sbc Sc Sb pec Sc pec Sbc pec 10 pec 10 pec 10 SO Im S pec SBd Sa Sa pec S pec Sm pec E pec Sb SBm SBm/Im Pec SO SO SBb Sa Sa Sm pec SO pec Type (3) ! Galaxies intheAtlas cz (kms) 2100 6480 2650 2900 4780 2440 4960 4110 2410 2840 2970 2140 6600 7600 6020 6300 2700 3100 2670 5120 3310 5430 1210 1860 1200 1250 1640 1600 1050 1380 1830 1740 1040 1070 1100 1090 1770 (4) 470 680 940 760 610 760 820 820 410 250 590 820 780 280 550 840 140 160 TABLE 1 M(£) -20.5 -20.1 -20.2 -20.3 -19.9 -21.2 -20.2 -19.9 -22.0 -20.6 -20.6 -20.5 -19.9 -20.2 -19.3 -18.4 -19.2 -19.3 -22.1 -19.0 -21.5 -19.7 -19.8 -20.0 -20. -22.4 -19.0 -20.8 -20. -19.9 -22.2 -21.2 -20.5 -14.8 -16.6 -17.7 -17.6 -20.2 -20.4 -19.2 -18.9 -21. -20.8 -21.4 -19.9 -21. -18.8 -17.1 -18.5 -18.1 -18.3 -17.9 -16: -20.7 -20.7 (5) Instrument (m) 0.9 0.9 2.3 2.3 2.3 2.3 2.3 2.3 2.3 2.3 2.3 2.3 2.3 2.3 2.3 2.3 2.3 2.3 2.3 2.3 2.3 2.3 2.3 2.3 2.3 2.3 0.9 0.9 0.9 0.9 2.3 2.3 2.3 2.3 (6) 0.9 0.9 0.9 0.9 2.3 2.3 2.3 0.9 0.9 2.3 2.3 2.3 0.9 2.3 2.3 2.3 0.9 2.3 2.3 2.3 2.3 800 X110 314 X120 120 X 120 X180 120X90 165 X45 120 X180 150 X360 150 X180 120 X 150 X180 120 X90 180 X120 120 X60 120 X 120 X20 120 X180 Aperture 90X600 90X90 90X90 90X90 90X90 60X60 60X60 90X90 90X90 90X45 90X90 90X60 40X45 60X45 90X90 90X65 90X90 60X90 60X45 60X45 60X45 60X60 60X45 60X45 75X60 (7) 45 45 45 45 45 45 45 45 45 45 45 45 45 Notes 20 20 22 20,21 12, 15 12, 14 11 18 17 16 12, 13 19 19 4 6 4 4 6,8 7 4,12 4, 10 4,9 5 4, 20 4, 19 4, 24 4, 23 4 (8) 19 92ApJS. . .79. .255K population arenowevident. The mostobviousistheappear- nated byevolvedgiantstars,additional signaturesofayounger were observedwiththe2.3mtelescope,whilespectrum of made withthe0.92mtelescopeand1RS. NGC 5866isthesumofthreepairsnebularobservations elliptical galaxiesdiscussedabove.NGC3245,3941,and4262 equivalent widthsofafewangstromsorless,similarto the guishable fromthoseoftheellipticalgalaxiesinFigure5, at Weak [On]and[Nemissionisfrequentlyobserved,with (Gregg 1989),itprobablywouldnotbedetectedinourdata. low-level bluecontinuumfromyoungstarswerepresent least withintheerrorsofdatapresentedhere.Even ifa terstellar gas(e.g.,Osterbrock1960). bly originatesinthenucleusmostcasesorfromdifíüsein- are almostalwaysseeninabsorption.Thefineemissionproba- Approximately halfoftheearly-typegalaxiesinsurvey show detectable[On]emissionintheintegratedspectrum. in equivalentwidthfrom0to4ÁamongtheE/S0galaxies. good illustrationofthecalibrationerrorsdiscussedin§2.3. seen emissionfine,whenpresent,is[On]X3727,whichvaries as intheSOgalaxiesillustratedFigure6.Themosteasily tinuum slopeslongwardof5500ÂbetweenNGC3379andthe tral resolutionontheobservedspectra.Thedifferenceincon- tion withthe1RSandillustrateswelleffectofreducedspec- [N n]X6583issometimesdetectedaswell.TheBalmerfines other galaxiesisprobablyinstrumental,andthisservesasa tion infinefeaturesaremainlyduetodifferencesmetalficity and finebroadening.NGC4472wasobservedatlowresolu- dominated byabsorptionfeaturesfromcoolgiants.Thevaria- be identifiedbycomparisonwithFigure19,whichshowsfour given here.Nebularemissionfeaturesinthegalaxyspectracan presents dereddenedspectrafor134starsinthesameformatas H ngalaxies. sons IreferthereadertoJacobyetal.(1984)paper,which prominent absorptionfeatures.Formoredetailedcompari- and mayprovideausefulmeansofidentifyingmanythe duces spectrafor4referencestarsfromthelibraryofJacoby, tion features(e.g.,theBbandnear6870Á)havenotbeen be consultedforidentificationofthesefines.Telluricabsorp- nant contributorstotheintegratedstarlightinmostgalaxies, Hunter, &Christian(1984).Thesestarsincludethepredomi- removed. clipped, exceptincaseswheretheUnesfallnearrealspectral features inthegalaxies.ThenightskyspectrumFigure3can ual featuresfromthebrightestnightskyUnes(mainly[Oi] X5577, 6300,6363,NaDwhensufficientlyisolated)havebeen Although thevisiblespectraof thesegalaxiesarestilldomi- As aclassthespectraofSOgalaxiesarenearlyindistin- Nebular emissionfinesareabsentorweakinthesegalaxies, The ellipticalgalaxiesshowrelativelyhomogeneousspectra, As anaidtointerpretingthegalaxyspectra,Figure4repro- 3.3. DescriptionofGalaxySpectra:NormalGalaxies 3.3.3. Sa-SabGalaxies(Figs. 7and12) © American Astronomical Society • Provided by theNASA Astrophysics Data System 3.3.2. S0-S0/aGalaxies(Fig.6) 3.3.1. EllipticalGalaxies(Fig.5) SPECTROPHOTOMETRIC ATLASOFGALAXIES galaxies inFigure9arearranged toillustratethevariationsin late-type giants,however. continuum shapeandemission-fine strength,whileFigure10 guish thespectrumofanearly-tointermediate-typespiral Balmer fines.Thevisible-redcontinuumisstilldominatedby dominated absorptionfeaturesbegintoweakeninfavorofthe readily apparent(alsoseeFig.12),andtheG-K-giant- trum ofaprototypeScgalaxy(seeFigs.9-10). able emissionfine.Abluecontinuumfromyoungstarsis from anE/S0galaxy.Thispointisaddressedfurtherin§3.3.7. emission finetohighaccuracy,itwouldbedifficultdistin- able tomeasurethebluecontinuumcolorsor[On]X3727 both thecontinuumandemissionfines,isverylarge,re- Blueward ofHa,however,[On]istheonlyconsistentlydetect- ent intheSbgalaxies.Nebularemissionfinesarenowpromi- slow progressionofspectralproperties(exclusivetheHa + morphological classification,e.g.,NGC1832,withthespec- examples ofgalaxieswhosestellarcontentdonotmatchtheir unit masswithintheclass(Kennicutt1983).Againthere are nent features,includingHa+[Nn],withequivalentwidthsof tegrated spectrashowanexcefientcongruitywiththepurely general thesequenceofstellarpopulationsrevealedbyin- flecting thenearlytenfoldvariationinstarformationrateper morphological classificationsofdeVaucouleursetal.(1976) pares spiralswithinagivensubtype(e.g.,Savs.Sab)orocca- and Sandage&Tammann(1981). sionally evenbetweenadjacenttypes(e.g.,Sbvs.Sc),butin tion woulddiffersomewhatfromatraditionalmorphological galaxies. Thisillustrateshowapurelyspectroscopicclassifica- [N n]emissionfines)betweentypesEandSb.Unlessonewere shows thatsuchinconsistenciesarecommonwhenonecom- ogy, orspiralarmproperties.Examinationoftheentiresample classification basedondiskresolution,bulge/diskmorphol- types. Forexample,thespectrumofNGC1357,anSagalaxy ~5-30 Á,andweakeremissionin[Nn],[S[On]. of NGC3368or488(notshown),bothclassifiedasSab ( Sandage&Tammann1981)isconsiderablybluerthanthose spectra arenotalwayscorrelatedwiththeirpublishedHubble ties intheemissionfinesandbluecontinuum,which mass orarea(cf.Caldwelletal.1991).Thesedifferencesin presumably reflectsarangeinstarformationratesperunit break (alsoseeFig.22).Theabsorptionspectraalsobeginto H7), butthisisnotreadilyapparentintheplotsshownhere. show subtlechanges(e.g.,CanKvs.H+HeorGband in thecontinuumblue,especiallyat4000ÁH+K absorption. Thepresenceofayoungerpopulationcanbeseen widths ofthesefinesareusuallyonlyafewangstroms,andthe Balmer fines,includingHa,arestillstronglyaffectedbystellar ance ofemissionfines(indecreasingorder)[Nn]X6583,[O X3727, Ha,andrarelyHßor[Om]X5007.Theequivalent Figures 9and10showspectra foreightSbc-Scgalaxies.The Perhaps themostsurprisingresultinFigures5-8isvery The presenceofamixedagestellarpopulationismostappar- The rangeofspectralpropertiesamongtheSbgalaxies,in The Sa-Sabgalaxiesdisplayalargerangeinspectralproper- 3.3.5. Sbc-ScGalaxies(Figs. 9, 10,12,and18) 3.3.4. SbGalaxies(Figs.8and12) 261 o o

o co10

o oco

o LO

o LOo

o o

LO cvi (OOSS)á / (\)i

262

.—Integrated spectra of four elliptical galaxies. The spectrum of NGC 4472 ( lower right) was obtained at lower resolution with the 1RS scanner. 19 92ApJS. . .79. .255K © American Astronomical Society • Provided by theNASA Astrophysics Data System 264

Fig. 6.—Integrated spectra of four SO galaxies. The spectrum of NGC 5866 (lower right) was obtained at lower resolution with the 1RS scanner. 19 92ApJS. . .79. .255K © American Astronomical Society • Provided by theNASA Astrophysics Data System 265

Fig. 7.—Integrated spectra of four Sa-Sab galaxies 19 92ApJS. . .79. .255K © American Astronomical Society • Provided by theNASA Astrophysics Data System 266

Fig. 8.—Integrated spectra of four Sb galaxies 19 92ApJS. . .79. .255K © American Astronomical Society • Provided by theNASA Astrophysics Data System (009S)á /(y)jl 267 (0099)1 /(Y)¿ IÛ to S 5 O o o O lO O O l£ II (O iß O O i- O O O tí

Fig. 9.—Integrated spectra of four Sbc-Sc galaxies, selected to illustrate the range in emission-line strengths and blue continuum properties. See Fig. 10 for other examples. 19 92ApJS. . .79. .255K © American Astronomical Society • Provided by theNASA Astrophysics Data System (OOSQ)i /(\)¿ 268 (0099)á /(Y)I o O O Iß o Iß iß Û0 (O o iß O % S 5 o o O o o o 1) a Q)

Fig. 10.—Integrated spectra of four Sbc-Sc galaxies, selected to illustrate the range in excitation in the emission-hne spectra. See Fig. 9 for other examples. 19 92ApJS. . .79. .255K © American Astronomical Society • Provided by theNASA Astrophysics Data System 269

Fig. 11.—Integrated spectra of three Magellanic irregular galaxies (NGC 4449, 4485, 1569), and one peculiar galaxy with a very similar spectrum (NGC 4670). 19 92ApJS. . .79. .255K © American Astronomical Society • Provided by theNASA Astrophysics Data System (ooss)á /(y)j 270 (00S9)J /(Y)á

3600 4000 4400 4800 5200 3600 4000 4400 4800 5200 Wavelength (A) Wavelength (A) Fig. 12.—Expanded plots of the integrated blue spectra for four spiral and irregular galaxies, illustrating the progression in continuum energy distributions and absorption-line spectra along the Hubble sequence. 19 92ApJS. . .79. .255K © American Astronomical Society • Provided by theNASA Astrophysics Data System 271

4000 4500 5000 5500 6000 6500 7000 4000 4500 5000 5500 6000 6500 7000 Wavelength (A) Wavelength (A) Fig. 13.—For each galaxy the quantity plotted is the observed spectrum (normalized to unity at 5500 À) divided by the mean spectrum of a set of elliptical and SO galaxies. The four galaxies are the same as those in Fig. 12. 19 92ApJS. . .79. .255K © American Astronomical Society • Provided by theNASA Astrophysics Data System 272

r. 14.—Integrated spectra of four M82-type 10 ( or Irr II ) galaxies. See Fig. 15 for expanded plots of the blue spectra. Compare the spectrum of NGC 3077 with the Sbc-Sc galaxies i: 19 92ApJS. . .79. .255K © American Astronomical Society • Provided by theNASA Astrophysics Data System (OOSQ)jI /(V).i 273 (009S)¿ /(Y)¿ iß CV2 o o o co O O o o (O o O -I §§ co QÛ

15.—Expanded plots of the integrated blue spectra for the four 10 galaxies illustrated in Fig. 14 19 92ApJS. . .79. .255K © American Astronomical Society • Provided by theNASA Astrophysics Data System (ooss)jI /(y)d 274 (009S)i /(Y)i

16.—Integrated spectra of four spiral and irregular galaxies with global starbursts 19 92ApJS. . .79. .255K © American Astronomical Society • Provided by theNASA Astrophysics Data System (ooss)i /(y)j LO o O o o o o LO o o o LO LO o o co o o co iß o o O O O 275 (OOQQ)jI /(Y)jí

£ 17.—Integrated spectra of four spiral galaxies with luminous starburst nuclei 19 92ApJS. . .79. .255K © American Astronomical Society • Provided by theNASA Astrophysics Data System 276

Fig. 18.—Expanded plots of the integrated blue spectra for a nuclear starburst galaxy (NGC 2798 ), and a galaxy with a global starburst (NGC 3310), compared to two “normal” blue spiral and irregular galaxies (NGC 4775, NGC 1569). The red slope of the spectrum of NGC 1569 is due to high Galactic foreground reddening. 19 92ApJS. . .79. .255K © American Astronomical Society • Provided by theNASA Astrophysics Data System ni

Fig. 19.—Spectra of four extreme emission-line galaxies. The observations of Mrk 35 and Mrk 487 approximate integrated spectra, while the observations for Mrk 59 and Mrk 71 are centered on supergiant H n regions. Along with NGC 1569 (Figs. 11 and 18) these comprise the lowest luminosity and mass galaxies in the atlas. 19 92ApJS. . .79. .255K © American Astronomical Society • Provided by theNASA Astrophysics Data System to to o o o o o o o to o o to o co o o o co o o o o o 278 (00S9)¿ /(Y)¿

4000 4500 5000 5500 6000 6500 7000 4000 4500 5000 5500 6000 6500 7000 Wavelength (A) Wavelength (A) Fig. 20.—Integrated spectra of three spiral galaxies with Seyfert 1 nuclei. Also shown is the nuclear spectrum (2" X 16" aperture) for NGC 5548. Note how many of the Seyfert features in the blue become lost in the integrated spectrum of the galaxy. 19 92ApJS. . .79. .255K © American Astronomical Society • Provided by theNASA Astrophysics Data System 279

Fig. 21.—Integrated spectra of four spiral galaxies with Seyfert 2 nuclei 19 92ApJS. . .79. .255K © American Astronomical Society • Provided by theNASA Astrophysics Data System (ooss)ji /(y)¿ (009S)á /(y)¿ O O r*- o

Fig. 22.—Integrated spectra of four peculiar galaxies. NGC 1275 is located in the core of the Perseus cluster. The other three galaxies show morphological evidence of recent mergers. 19 92ApJS. . .79. .255K the onlyfactor)isasubstantialvariationinmeanHnregion the Balmerfines.Thechiefcauseforthesedifferences(butnot grated spectraofdistantgalaxiesshouldbeabletoprovide range inmeanexcitation(e.g.,McCall,Rybski,&Shields of individualHnregionsinScgalaxiesshowacomparable abundance amongthegalaxies.Observationsoflargenumbers tation amongtheScgalaxies.Noteinparticularvariation bly dueinparttovariationsreddeningamongthegalaxies, representative sampleofirregular galaxies.ThehighHaequiv- young starsandHnregions. Thismaynotbeacompletely in chemicalabundanceswithcosmologicallookbacktime. offers thetantalizingprospectofdirectlyprobingevolution abundance whichisapparentinFigure10suggeststhatinte- diffuse interstellargas,maybeimportant.SeePaperIfor a in theratioof[Om]\5007toH0,andn]X3727relative as welldifferencesintheirrecentstarformationhistories. these differencesarenotparticularlywellcorrelatedwithmor- some quantitativelimitsontheirchemicalcomposition.This more detaileddiscussion. on thebasisofabundancevariationsalone,however,andother range in[On]/Hßissomewhatlargerthanwouldbeexpected tribute tosystematicabundancevariations,ranginginO/H spectrum donotalwayscorrelatemonotonically.Thisisproba- veals thatcontinuumshape,absorptionspectrum,andfine phological type.Carefulexaminationofthespectraalsore- type) thanontheYerkessystem. where bulgefightismuchmoreimportant.Ifoneweretode- factors, suchasreddeningvariationsandcontributionsfrom from afewtenthssolarto1-2timesabundance.The similar towhatwasseenfortheearly-typespirals.Onceagain, large rangeintherelativecontributionsofyoungandoldstars, the spectraltypeswouldbesystematicallyearlier(instellar calibrated onthebasisofspectranear-nuclearregions, fine aclassificationforspiralsbasedontheirintegratedspectra, ence canbeattributedtothefactthatMorgantypeswere cal ScgalaxyhasameanspectraltypeofFtoG-K.Thediffer- Yerkes system(Morgan1958);ontheMorgansystem,atypi- cantly fromthespectralclassificationofthesegalaxieson have becomethedominantspectralfeature.Thisdifferssignifi- in theblue,Balmerspectraofearly-typeyoungstars contributions fromboththeGandKgiantsA-Fstars,but lar continuumandabsorptionspectrumiscomposite,with which arecharacteristicofstar-formingHnregions.Thestel- are apparentintheintegratedspectrum,withrelativestrengths line spectraoftheSbc-Scgalaxiesarequahtativelydifferent nebular emissionlines(Ha,Hß,[On],m],[N[Sn]) from thoseoftheearlierHubbletypes.Allprincipal age distributionandmeandiskmetalabundance,respectively. demonstrates thelargerangeinnebularexcitation.Presum- 1985; Zaritsky,Elston,&Hill1990),whichtheseworkersat- ably thesedifferencesreflectunderlyingvariationsinstellar The spectraofthesegalaxies arecompletelydominatedby The sensitivityoftheintegratedspectrumtomeandisk Figure 10illustratestheverylargerangeinnebularexci- Figures 9-10showthatwithintheSbc-Scclass,thereisa The continuumshapes,absorptionspectra,andemission 3.3.6. MagellanicIrregularand SpiralGalaxies © American Astronomical Society • Provided by theNASA Astrophysics Data System (Figs. 1112,and18) SPECTROPHOTOMETRIC ATLASOFGALAXIES ward of4500Á,thespectral shapes areidenticaltowithinthe this youngerstarlightatvariouswavelengths.IntheSagalaxy inated population.Theratiosgivenontheverticalscales pro- the blueisduetoslightdifferencesinpositionsandprofiles lation ineachcase.Notethatmostofthechoppystructure in errors ofourspectrophotometry. Alsonoticehowclearlythe uum, atmost,iscontributedbyabluepopulation,andlong- NGC 2775,forinstance,only10%-15%ofthebluecontin- vide averyroughindicationofthefractionalcontribution of continuum shapewhichischaracteristicofanA-Fstar-dom- hence thisstructureisnotmeaningful. trum inFigures5-11istheincreasestrengthsof by Balmerfines,consistentwiththeclassificationofthesegalax- tral regionareshownforNGC4449and1569inFigures than canbesustainedoveraHubbletime,i.e.,weareobserv- clearly intheSbgalaxyNGC 4750,andthefractionofblue vided bythereferencespectrum. TheBalmerfinesappear Ha andHßemissionfinesemerge fromabsorptionwhendi- of strongfinesbetweenthegalaxyandtemplatespectra, and the relativeamountsofexcessfightoverapurelyevolvedpopu- yields similarresults.Figure13providesadirectindicationof the objectandreferencespectrum(ratherthanquotient) A referenceE-S0galaxyspectrumwascreatedbysummingthe with galaxytypeisshowninFigure13.Thesearenotobserved the nebularspectrumareaccompaniedbymoresubtlechanges ies asAorA-FontheYerkessystem(e.g.,Morgan&Mayall is referredtotheextensiveseriesofpapersbyGallagher& ing themduringanextendedstarformationburst.Foramore (Im) bythereferencespectrum.Takingdifferencebetween in thecontinuumandabsorptionspectraaswell.Thisisper- grated starformationrateinnormalgalaxies(e.g.,Kennicutt along theHubblesequence.Themostevidentchangeinspec- is usefultomakeadirectcomparisonofthechangesinspectra sorption featuresinFigure10.Expandedplotsofthebluespec- nate thespectra,makingitdifficulttodiscernstellarab- Hunter (e.g.,&Gallagher1985,1986). representative crosssectionofMagellanicirregulars,thereader alent widths(65-200Á)andverybluecolorsindicatethatall 2775 (Sa),NGC4750(Sb),6643(Sc),and4449 shows theresultofdividingnormalizedspectraNGC shift), andrenormalizingtounityat5500Á.Figure13then selected becausetheyallhaveapproximatelythesamered- normalized spectraofNGC3245,4262,and4648(thesewere spectra, butratiosofnormalizedcomputedasfollows. Magellanic irregulargalaxies. of thebluespectralregionforexamplesSa,Sb,Sc,and haps bestillustratedinFigure12,whichshowsexpandedplots makes theHafinebestquantitativeindicatorofinte- nebular emissionfines,especiallyHa+[Nn].Thissensitivity four galaxiesarecurrentlyformingstarsatamuchhigherrate 1957). 12 and19,respectively.Theabsorptionspectrumisdominated 1983, Gallagher,Hunter,&Tutukov1984).Thesechangesin All fourgalaxiesshowanexcessofyoungerstarlight,with a At highspectralresolutionthenebularemissionfinesdomi- A morequantitativedepictionofthesechangesinspectrum Before proceedingtoadiscussionofthepeculiargalaxies,it 3.3.7. SummaryofGeneralTrendswithHubbleType 281 19 92ApJS. . .79. .255K present inNGC5195.Thespectrum alsoresemblesthoseob- Gunn 1983,1990),exceptthat [Nn]and[Oemissionare which arecommonlydetected athighredshift(e.g.,Dressier& trum. Thisissimilartothe spectra ofblue“E+A”galaxies would bemistakenforanormalScgalaxy!NGC5195, the sorption Unessuperposedupon anevolvedunderlyingspec- ulation, withweakemissionUnesandverystrongBalmer ab- irregular companiontoM51,showsahighlymixedstellarpop- ( cf.Figs.9-10).IfwewereunawareoftheappearanceNGC its spectrumisindistinguishablefromthatofanormalspiral NGC 3077ismorphologicaUysimilartoM82and5195, Figs. 16-18). 3077 andweretoclassifyitsolelyonthebasisofitsspectrum, it flux byafactorofbiflions)thannormalstarburst (cf. more characteristicofasupernovaremnant(multipUed in Unes of[On]A3727,in]XX4959,5007,i]XX6300,6363, pecuhar, iscompletelydifferent,withstrongbroadforbidden very highreddening.ThespectrumofNGC6240,whilealso shocked gas(notethestrong[Nn]/Haand[Sn]/Ha),with istic ofacombinationnormalstar-formingregionsand pletely different.ThenebularUneratiosinM82arecharacter- Ha +[Nii]emission,buttheirforbiddenfinespectraarecom- in Figure14,theirspectralpropertiesareremarkablyheteroge- [N n]XX6548,6583,and[SXX6717,6731.Thisspectrum is neous. BothM82andNGC6240aredominatedbystrong this classarealsostrongfar-infraredsources.Someappearto mergers (e.g.,NGC5195,6240). have beenformedastheresultofgalaxyinteractionsor sorption patchesfrominterstellardustclouds.Mostgalaxiesof amorphous mainbody,faintfilamentarystructure,andab- prototype forthisclassisM82,andallfourofthegalaxies selected herehaveverysimilaropticalmorphologies,withan content andevolutionaryhistories. properties, whichmayofferimportantcluestotheirstellar these galaxiesalsoexhibitunusualandoftenuniquespectral burst oremissionUnegalaxies.AsillustratedinFigures14-22, type 10(IrrII)galaxies,aswellstronglyinteractingsystems, to encompassmorphologicallypeculiarobjects,suchasM82- mergers, galaxieswithactivenuclei,andunusuallystrongstar- axies ofvarioustypes.HereIusetheterm“pecuhar”loosely, spectral propertiesofthoseobjects,andtheirdependenceon Hubble type,couldbequitedifferent. Mahn 1(Impey&Bothun1989)arenotrepresented.The practical reasons,verylowsurfacebrightnessgalaxiessuchas dominated bybright,highsurfacebrightnessgalaxies.For region. trum, contributingoverhalfofthetotalluminosityinthat type Sc,theexcessbluecomponentdominatesspec- starlight risestooforder20%-50%shortward4300Á.By 282 NGC 3077and5195representotherextremes.Eventhough Despite themorphologicalsimilaritiesbetweengalaxies Figure 14showsspectraforfournearby10galaxies.The The remainderoftheatlasillustratesspectrapeculiargal- One shouldbearinmindthatthesamplepresentedhereis 3.4. DescriptionofSpectra:PeculiarGalaxies 3.4.1. 10(IrrII)Galaxies(Figs.14and15) © American Astronomical Society • Provided by theNASA Astrophysics Data System KENNICUTT young stellarpopulationdominates theentirespectrum.The with globalstarbursts(e.g.,NGC 3310inFig.18),wherethe spectrum oftheSagalaxy.This isuncharacteristicofgalaxies absorption spectrumshows a highlycompositenature,with these galaxies,showninFigure18,revealssomedifferences. In Balmer finesfromthestarburst superposedonared,evolved starburst nucleuswithinarelativelyquiescentSagalaxy, the NGC 2798,forexample,whichconsistsofaveryluminous tra wereavailable.Aclosercomparisonofthebluecontinua of ble thoseinFigure16;itwouldbedifficulttodistinguish between globalandnuclearstarburstsifonlytheintegratedspec- galaxies areoftenofearlierHubbletype.Theemission fine spectra ofNGC7714,2798,andMrk691closelyresem- concentrated inanHnregion-likenucleus,andtheparent Figures 16and19,inthatmostofthestarburstactivity is as definedbyBalzano(1983).Thesedifferfromthegalaxies in tation, whichisconsistentwiththefactthatthesetendtobe between theseluminousstarburstgalaxiesandtheMagellanic more massive(andprobablymetal-rich)galaxies. irregulars showninFigure11isasomewhatlowermeanexci- late-type, activestar-forminggalaxies.Theprincipaldifference average SborScgalaxy.Thestellarcontinuaalsoresemble from 77to234Â(PaperI),3-10timeshigherthaninan in thesurvey,withequivalentwidthsofHa+[Nn]ranging intergalactic medium(Gavazzi&Jaffe1987). appears tobeundergoingastronginteractionwiththelocal center ofthegalaxyandtidaldebrisatlargeradiihaveled the presenceofanucleuswhichisoffsetfromdynamical is entirelyinstrumental.NGC3310asingleSbcgalaxy,but merger. UGC6697islocatedintheAbell1367clusterand Balick &Heckman(1981)toclassifythesystemasanevolved going globalburstsofstarformation.NGC3690and and theapparentUnebroadeningrelativetoothergalaxies interactions ormergers.Thespectraweretakenwiththe1RS, 6052 aredoublesystemswhichcurrentlyundergoingclose galaxies asaclass.Moreextensiveobservations,covering understand thenatureofthesegalaxies. larger sampleandproperlytakingintoaccounttheeffectsof galaxies observedhere(notwoofthespectraareaüke),how- reddening andnonthermalemission,arebeingmadetobetter ever, itisimpossibletodrawfirmconclusionsaboutthe10 phous” galaxies.Giventhediversityofspectrafour them atdifferentevolutionarystages.Thisisconsistentwith terpretation oftheseresultsisthataUfourgalaxiesareexperi- conclusions drawnbyGaUagher&Hunter(1987),basedon encing large-scalestarformationbursts,butweareobserving ies showevidenceforacompositesteUarpopulation,including strong BalmerabsorptionUnes.Themoststraightforwardin- surprisingly similar,asülustratedinFigure15.AUofthegalax- spectra amongthese10galaxies,theabsorptionUneare al. 1988). served forthenucleiofmanysheUelhpticalgalaxies(Carteret UBV andHaobservationsofalargesamplesimilar“amor- Figure 17showsspectraforfournuclearstarburstgalaxies, These galaxiespossesssomeofthestrongestemissionfines Figure 16showsfourexamplesofgalaxieswhichareunder- 3.4.2. StarburstandEmission-LineGalaxies(Figs.16-19) In contrasttothiscompletedissimilarityinemissionUne Vol. 79 19 92ApJS. . .79. .255K biguous signatureofanactive nucleus,butasinthecaseof this casetherearenobroadBalmer finestoprovideanunam- tive meansofseparatingthe two typesofobjects. parent galaxy,isquitedistinctfromthatinastarburstgalaxy (compare withFigs.16-18), and thisoftenprovidesaneffec- ies closelyresemblethoseseeninstarburstgalaxies,theunder- though thestrong,narrowforbiddenlinesinSeyfertgalax- lying stellarcontinuum,oftendominatedbytheearly-type blend intothecontinuumofparentgalaxy(e.g.,NGC means ofidentifyingtheSeyfertgalaxiesinthissituation. Al- distant galaxies.Unlessthenucleusismuchbrighterthan the surrounding galaxy,thehigh-velocitywingsofBalmerfines The separationislessstraightforward,however,ifonlytheblue easily identifiedbythepresenceofverybroadHaemission: with thenuclearspectrumofonegalaxies(NGC5548). bursting emissionfinegalaxies. spectral regionisavailable,asoftenthecaseinsurveys of When thefullopticalspectrumisavailable,thesegalaxiesare grated spectraaredifficulttodistinguishfromthoseofstar- preferentially detectedinsuchsurveys,andoftentheirinte- 3516 andNGC5548inFig.20).PaperIdiscussesquantitative cially Seyfertgalaxies,areofparticularrelevancetospectro- galaxy mightappear. provide anindicationofhowthespectrumatrulyprimeval tion. TheO/HabundancesinMrk59and71areapproxi- scopic surveysofdistantgalaxies,becausesuchgalaxiesmaybe mately 0.1solar(Garnett1989).Consequentlythoseobjects dances, andthisisseenasaverylargerangeinnebularexcita- be dominatedbythegiantHnregions.ThegalaxiesinFigure a largedistance,itislikelythattheirintegratedspectrawould spective galaxies.However,ifeithergalaxywereobservedfrom axies NGC4861and2363,respectively,hencetheir tially integratedmeasurements.Mrk59and71arelarge the spectrawereobtainedwith1RSusing45"apertures. spectra arenotstrictlyintegratedmeasurementsoftheirre- H n/OBcomplexeswithinthenearbyMagellanicirregulargal- Two oftheobservations,forMrk35and487,areessen- fine galaxies.InthesecasestheequivalentwidthsofHa+ can betoclassifyadistantgalaxybasedonitsbluespectrum which wasidentifiedasastarburstgalaxyonthebasisofits alone. available. Thisprovidesanotherillustrationofhowdifficultit identified asastarburstatallifonlyitsbluespectrumwere Unes intheblue,andarelativelyredcontinuum.Thisobject, optical morphologyandstrongHaemission,wouldnotbe very strongHaand[Nn]emission,butonlyweakemission (NGC 3471)showsaverydifferentintegratedspectrum,with the innerregionsofmostspirals,butthisisnotalwayscase. which probablyreflectsthehighermeanmetalabundancesin starburst nucleialsotendtoshowlowernebularexcitation, [N ii]emissionfinesrangefrom160toover1000À!Allfourof 19 possessalargerangeintotalluminositiesandmetalabun- No. 2,1992 Figure 21showsspectraforfour nearbySeyfert2galaxies.In Figure 20showsspectraofthreeSeyfert1galaxies,along The integratedspectraofgalaxieswithactivenuclei,espe- Finally, Figure19showsfourexamplesofextremeemission- One ofthenuclearstarburstgalaxiesinFigure17,Mrk158 3.4.3. SeyfertGalaxies(Figs.20and21) © American Astronomical Society • Provided by theNASA Astrophysics Data System SPECTROPHOTOMETRIC ATLASOFGALAXIES cal DataCenterBulletin,or transmit theinformationon submit theformpublishedin thelatestissueof\Y±zAstronomi- over anelectronicnetwork.Individuals shouldcompleteand form, eitheronmagnetictape orpossiblyviatransmission (ADC). Thedatamaybe obtained inmachine-readable available uponrequestfromtheAstronomicalDataCenter paper willbedifficulttouse.Adigitalversionofthedata is the class.Observationsofamuchlargersampleareinprogress, trum, butwithextremelystrong[On]emission.Aswasthe (C. T.Liu&R.C.Kennicutt,inpreparation). and theyshowanevenlargerdiversityinspectralproperties draw anygeneralconclusionsaboutthespectralproperties of tion (butmuchweaker)superposedonanolderstellarspec- case withthe10galaxiesdiscussedearlier,mergersshow dence ofsomethesamefeatures,includingBalmerabsorp- between thosegalaxiesandthenearbyexamplesofmergers such awiderangeinspectralpropertiesthatitisimpossible to spectrum ofNGC3303ispoorerquality,butitshowsevi- to betherelicsofmergersatearliercosmologicalepochs(e.g., offers somecircumstantialsupporttothishypothesis.The Dressier &Gunn1983),andthespectroscopicresemblence served athighredshift.TheE+Agalaxieshavebeenpostulated in Figures16-18.NGC3921showsamixedpopulation,with nearby analogtothe“E+A”galaxieswhicharefrequentlyob- extraordinarily strongBalmerabsorptionfines.Thisisanother ples ofhowgalacticmergerscanalterthestellarpopulations. starburst andcloselyresemblestheotheremissionfinegalaxies The spectrumofNGC4194(Mrk201)isdominatedbya cluster (Heckmanetal.1989),andthisspectrumprovides galaxies isproducedbyacoolingflowinthecoreofPerseus ized gasareclearlyresolvedhere.Muchoftheemissioninthis in thesurvey.Thetwowell-knownvelocitysystemsion- some indicationofhowadistantcoolingflowmightappear. with anothergalaxy(NGC3303,3921,4194),oralarge falls inthiscategory. 6240, withthebizarrespectrumshowninFigures14-15,also amount ofintergalacticgas(NGC1275).The10galaxyNGC among theseobjectsisevidenceofarecentmergerevent,either tends totheirintegratedspectraaswell.Acommontrait most peculiarobjectsinthesurvey,andthispeculiarityex- tion spectrumwillbevirtuallyindistinguishablefromthatofa cially atlowspectralevolution,andtheresultinghighexcita- many Sc-IrrandstarburstgalaxiesstrongstellarBalmerab- cient evidencetoclassifythespectrumasaSeyfertgalaxy.In Seyfert 2galaxy. sorption willvirtuallyobliteratetheH0emissionfine,espe- high-excitation emission-finespectrumisnotbyitselfsuffi- active nucleus,ratherthanastarburst.Notethepresenceof tinuum isthebestindicationthatemissionarisesfroman tion emission-finespectrumandarelativelyred,evolvedcon- Seyfert 1galaxies,themismatchbetweenastrong,high-excita- For manyapplications,thereducedplotsshowninthis The otherthreegalaxiesinFigure22showdifferentexam- The integratedspectrumofNGC1275isthemostpeculiar The fourfinalgalaxies,showninFigure22,areamongthe 3.5. AvailabilityoftheAtlasinDigitalForm 3.4.4. PeculiarGalaxies,Mergers(Fig.22) 283 19 92ApJS. . .79. .255K de Vaucouleurs,G.,&Corwin,H.G.1976,Second Carter, D.,Prieur,J.L.,Wilkinson,A.,Sparks,W.B.,&Malin,D.F.1988, Caldwell, N.,Kennicutt,R.,Phillips,A.C,&Schommer,R.1991,ApJ, Barnes, J.V.,Massey,P.,&Carder,E.1986,1RSInstrumentManual,Kitt baum, andVicHansen,forcapablepatientassistancewith .1990,inEvolutionoftheUniverseGalaxies,ed.R.G.Kron .1983,ApJ,270,7 Balzano, V.A.1983,ApJ,268,602 Balick, B.,&Heckman,T.1981,A&A,96,271 Jacoby etal.(1984)isalsoavailablefromtheADC. tronic mailtoTEADC@SCFVM(BITnet),TEADC@ Gregg, M.D.1989,ApJ,337,45 Gavazzi, G.,&Jaffe,W.1987,A&A,186,LI Garnett, D.R.1989,ApJ,345,282 Gallagher, J.S.,Hunter,D.A.,&Tutukov,A.V.1984,ApJ,284,544 Gallagher, J.S.,&Hunter,D.A.1987,AJ,94,43 CREQUEST (NSI-DECnet).Notethatthestellarlibraryof form totheADCbytelephone(301)286-8310,orelec- Huchra, J.P.1977,ApJS,35,171 Hubble, E.1926,ApJ,64,326 Heckman, T.M.,Baum,S.A.,vanBreugel,W.J.&McCarthy,P. Gallagher, J.S.,Bushouse,H.,&Hunter,D.A.1989,AJ,97,700 Elhs, R.S.1990,inEvolutionoftheUniverseGalaxies,ed.G.Kron Dressier, A.,&Gunn,J.E.1982,ApJ,263,533 SCFVM.GSFC.NASA.GOV (Internet),orNSSDCA::AD- 284 Reference CatalogofBrightGalaxies(Austin:Univ.TexasPress) MNRAS, 235,813 Peak NationalObservatory 370, 526 (ASP Conf.Ser.,10),248 (ASP Conf.Ser.,10),200 1989, ApJ,338,48 I wishtoexpressmythanksDennisMeans,GaryRosen- © American Astronomical Society • Provided by theNASA Astrophysics Data System KENNICUTT REFERENCES .1992,ApJ,inpress .1986,PASP,98,5 .1936,ApJ,83,18 .1959,PASP,71,92 Jacoby, G.H.,Hunter,D.A.,&Christian,C.A.1984,ApJS,56,257 Kennicutt, R.C.1983,ApJ,272,54 Humason, M.L.1931,ApJ,74,35 NSF grantsAST-8613257totheUniversityofMinnesota,and data whichappearinFigure4.Thisresearchwassupportedby tions. IamalsogratefultoRichardElston,HansRix,Tim the unorthodoxdrift-scanningobservations,andtoJoniJohn- Kormendy, J.,&Djorgovski,S.1989,ARA&A,27,235 Impey, C,&Bothun,G.1989,ApJ,341,89 Hunter, D.A.,&Gallagher,J.S.1985,ApJS,58,533 AST-8996123 andAST-9090150totheUniversityofArizona. ments andsuggestions.GeorgeJacobygenerouslysuppliedthe Heckman, NelsonCaldwell,andtherefereeforusefulcom- Osterbrock, D.E.1960,ApJ,132,325 Morgan, W.W.,&Osterbrock,D.E.1969,AJ,74,515 Morgan, W.W.,&MayaU,N.U.1957,PASP,69,291 Morgan, W.1958,PASP,70,364 McCaU, M.L.,Rybski,P.M.,&Shields,G.A.1985,ApJS,57,1 Massey, P.,Strobel,K.,Barnes,J.V.,&Anderson,E.1988,ApJ,328,315 son andDimitriKlebeforassistancewiththeKPNOobserva- Zaritsky, D.,Elston,R.,&Hill,J.M.1990,AJ,99,1108 Woolf, N.J.1982,ARA&A,20,367 Wells, D.G.1972,Ph.D.thesis,Univ.Texas Schild, R.,&Oke,J.B.1971,ApJ,169,209 Sandage, A.,&Tammann,G.A.1981,ARevisedShapley-AmesCatalog Whitford, A.E.1971,ApJ,169,215 Silva, D.R.1991,Ph.D.thesis,Univ.Michigan ton) of BrightGalaxies(Washington,DC:CarnegieInstitutionWashing-