198 7ApJ. . .312L. .11J -1 © 1987.TheAmericanAstronomicalSociety.Allrightsreserved.PrintedinU.S.A. The AstrophysicalJournal,312:L11-L15,1987January1 provided bytheInfraredProcessingandAnalysisCenter Norgaard-Nielsen, andJorgensen1985;Gallagher1986) in instrumentalsensitivity,ithasbecomepossibletoobserve brighter than=12.0magintheRevisedShapley-Ames produces opticalemissionUnes(Phillipsetal.1986).Jura essentially freeofinterstellarmatter.However,withadvances portions oftheskynotscannedbyIRAS.Thepreliminary (IPAC) toanalyzetheIRASdataforallellipticalgalaxies co-add theIRASdatatoreachagreaterlevelofsensitivity content. Currently,weareundertakinganextensiveprojectto given intheIRASPointSourceCatalogtostudytheirdust limits aregivenfornondetections. Catalog, exceptforNGC3078and3608whichare in our initialresultsaresostriking,wereportherethedatafor than availablewiththePointSourceCataloginacomprehen- (1986a) andTytler(1986)haveusedtheinfraredemission 21 cmemission(Knapp,Turner,andCunniffe1985;Wardle converted tomJy,andthe distances fromtheprescription given bySandageandTammann (1981),thefluxesatB fluxes forthese58galaxies,alongwiththeclassifications from someofthesegalaxiesaswellionizedgasthat thermal X-rayemission(Forman,Jones,andTucker1985) 1985; EbneterandBalickSparksetalHansen, and Knapp1986),opticaldustpatches(SadlerGerhard centric flowandH=100km sMpcaregiveninTable given byKnapp,Turner,and Cunniffe(1985)withVirgo- and analysiswillbepresentedinlaterpapers. Catalog (SandageandTammann1981).Detailsofthe data the brightestellipticalgalaxiesinRevisedShapley-Ames sive statisticalstudyofdustinearly-typegalaxies.Because 1. The1aerrorsarequoted foralldetections;3aupper 0 We haveusedtheone-dimensionalco-addingprocedure The traditionalviewofearly-typegalaxiesisthattheyare Most ofthepositive resultsshowninTable 1indicatereal 78 cold interstellarmatter.Thepresenceofgasinellipticalsthusappearstobetheruleratherthan Subject headings:galaxies:general—infrared:sources exception. the galaxies(withBj<\\mag)aredetectedat100/xmwithfluxlevelsindicating,typically,10orMof Shapley-Ames CatalogtoincreasethesensitivityoverthatofIRASPointSourceCatalog.Morethanhalf 0 © American Astronomical Society •Provided bythe NASAAstrophysics Data System We haveco-addedtheIRASsurveydataatpositionsofbrightestellipticalgalaxiesinRevised II. DATAANALYSIS INTERSTELLAR DUSTINSHAPLEY-AMESELLIPTICALGALAXIES I. INTRODUCTION Department ofAstronomy,UniversityCalifornia,LosAngeles Received 1986August11;acceptedSeptember30 G. R.KnappandP.Guhathakurta Princeton UniversityObservatory M. JuraandD.W.Kim ABSTRACT AND infrared emissionfromtheellipticalgalaxyinlineofsight. IRAS sourceagreetobetterthanV.(Theagreementisusually weight andmaynotbetheresultofellipticalgalaxyin much betterthanT.) Our criteriaforarealdetectionareasfollows: in thebeam,wehaveobtainedco-addedIRASdatafor18 (de Jongetal.1984;Jura1986a). randomly chosenlocationsofskywith\b\>30°.Inthis galactic cirrus(Lowetal.1984)orothercontaminatingsources observed direction.Inordertocheckforthepossibilityof IRAS band.Therefore,thegalaxiesthataredetectedonlyat sample, wefindno“detections”at12jLim;one“detection” Table 1isduetotheproximityofM31. instrumental noise.Thehighvalueofther.m.s.noisefor the in therandomlychosenpositions.Thepresenceofcirrus is consistentwitharateof-15%apparentdetectionsfound 25 /xm;no“detections”at60andtwo noise inthe100/xmdataissometimesmuchhigherthan the IRAS bandateither60/xmor100arequitepossibly emission isalsoapparentinseveralofourobservations; the 100 /xm.Noneofthese“sources”appearedinmorethanone 100 /xmobservationsofNGC185and221Usted in seven suchobjectsoutofthe58thatwehavemeasured; this spurious, andtheyarenotedassuchinTable1.There are /xm and100/xm.At12 itislikelythattheemission mainly arisesbothfromthe photospheresofstarsandfrom dust incircumstellarenvelopes aroundmass-losingredgiants (Soifer etal1986; Impey,Wynn-WilUams,and BeckUn1986). 4. Theinfraredcolorsgenerallyresemblethoseofgalaxies 2. Thefluxisatleast3timesther.m.s.noise. 1. Theopticalpositionofthegalaxyand 3. ThesourceisdetectedinmorethanoneIRASband. Some oftheapparentdetectionslistedinTable1arelow The elHpticalgalaxiesUsted in Table1arestrongestat12 III. RESULTS 198 7ApJ. . .312L. .11J NGC 147(dE5). NGC 185(dE3p) NGC 221(E2)... NGC 4486(E0).. NGC 1399(E1) NGC 3379(EO) NGC 1549(E2) NGC 1407(E0) NGC 4125(E6) NGC 4365(E3) NGC 4621(E5) NGC 4494(E1) NGC 4374(E1) NGC 4697(E6) NGC 596(E0).. NGC 5322(E4) NGC 821(E6).. NGC 720(E5).. NGC 1275(Ep) IC 1459(E4)... © American Astronomical Society •Provided bythe NASAAstrophysics Data System NGC 1395(E2). NGC 1404(E2). NGC 1427(E5). NGC 1537(E6). NGC 2325(E4). NGC 1700(E3). NGC 2300(E3) NGC 3136(E4). NGC 2986(E2). NGC 2974(E4). NGC 3193(E2). NGC 3377(E6). NGC 3250(E3). NGC 3557(E3). NGC 3613(E6). NGC 3610(E5). NGC 3640(E2). NGC 3904(E2) NGC 3706(E4). NGC 3962(E1). NGC 4261(E3). NGC 4373(E4), NGC 4278(E1). NGC 4589(E2) NGC 4564(E6) NGC 4473(E5) IC 3370(E2p). NGC 4696(E3) NGC 4660(E5) NGC 5018(E4) NGC 5061(E0) NGC 5044(E0) NGC 5813(E1) NGC 5576(E4) NGC 6482(E2) IC 4296(E0)... NGC 7507(E0) NGC 7144(E0) Galaxy (Mpc) (mJy) 13.5 16.4 12.9 13.5 18.9 115 13.5 12.9 24.7 11.7 14.8 16.6 18.4 17.5 52.5 15.7 14.9 17.9 22.3 21.8 12.1 22.5 38.3 25.2 29.0 15.8 18.6 25.7 23.0 32.1 22.3 31.2 12.0 D F(B) 18.5 0.7 11.7 0.7 35.1 0.7 30.5 24.8 13.5 13.5 13.5 9.3 29.9 30.6 7.6 23.1 31.4 43.1 21.5 P 23.8 37.4 19.0 14.4 6.0 7.9 1350 460 630 570 214 233 256 220 327 189 224 401 240 359 192 183 154 150 167 105 120 161 107 143 139 101 157 125 166 127 119 139 105 119 79 78 76 74 71 84 94 86 82 85 82 97 75 82 76 80 79 79 84 97 79 78 88 89 2 Fluxes fromShapley-AmesEllipticals < 90 < 87 < 69 < 117 < 90 < 66 < 105 < 99 < 54 < 132 < 96 < 99 < 111 < 69 < 60 < 75 < 84 < 105 < 105 < 108 < 81 < 123 < 114 < 96 < 108 < 174 < 129 < 138 12 /Ltm25/um60¿im < 168 < 96 < 102 < 87 < 117 450(39) 290(34) 90(25) 220(42) 100(20) 200(38) 150(35) 290(24) 190(44) 170(29) 90(28) 860(34) 120(28) 190(56) 130(26) 102 87 144 96 132 126 160(31) 105 140(23) 90(28) 10.0 stars inthesegalaxies.Exceptforthenearbydwarfgalaxies,a 15 kms"(KnappandMorris1985),cisthespeedof that ismoredistantfromthecenterlikelytobetoocold to the numbersofdetectedellipticals.Welloverhalf the estimatebyFaberandGallagher(1976). typical valueisveryroughly0.1Myr,inagreementwith 19866; Knapp1986).Numerically,equation(1)givesM 0v 0 At 100jam,themoststrikingresultshowninTable1isthat Following equation(5)ofJura(1986a),ifweassumethat L13 198 7ApJ. . .312L. .11J L14 78 dust at~20Kandifthedust-to-gasratiohasavaluesimilar the 100fimemissionfromthesegalaxiesisproducedbycold to thatintheMilkyWay,then: Table 1.Althoughtherangeofinferredvaluesisquitelarge, In equation(2),Disthedistanceofgalaxyinunits lar matterexceptforthenearbydwarfgalaxies. 100 /un.Themassesderivedfromthisanalysisaregivenin Mpc, and7^(100/un)isthefluxinJydetectedbyIRASat the typicalvalueisbetween10andMqofcoldinterstel- observations, thescatterinFigure2isconsiderablylarger much ofacorrelationbetweenthesetwoquantities.Despite than thatinFigure1.F^/Fgthushasawiderange for (Knapp, Turner,andCunnifle1985).Thesedataonthe dust these galaxies,similartothesituationwithHicontent content ofellipticalswillbediscussedmorethoroughly in are bettermatchedtothegalaxysizethan12/un the largerapertureofIRAS100/unobservationswhich future work. 100 de Jong,T.,etal.1984,Ap.J.(Letters), 278,L67. Cowie, L.L.,andBinney,J.1977, Ap.J.,215,723. Ebneter, K.,andBalick,B.1985, A.J., 90,183. of thebright(B°<11.0mag)“normal”ellipticalsin the Faber, S.M.,and Gallagher,J.S.1976,Ap.J.,204, 365. Shapley-Ames Catalogemit detectable 100/memission,and In Figure2weplot7;(100/im)versusF(B).Thereisnot y The firstresultofourinvestigationisthatmorethanhalf © American Astronomical Society •Provided bythe NASAAstrophysics Data System 52 M =1.6X10Z>F,,(100nm).(2) 0 IV. DISCUSSION JURA, KIM,KNAPP,ANDGUHATHAKURTA 78 _18 interstellar matterinellipticals.Thedoes interstellar gas. therefore containsignificantamounts,often10orM,of winds (MathewsandLoewenstein1986).Therefore,thepres- not appeartobecurrentlyflowingoutofthesegalaxiesas ence ofsomeinterstellarmaterialisnotsurprisingbecause Mq yr,wewouldexpecttodetectmuchmorethan10 galaxies. However,sincetheinjectionrateistypically~0.1 stars areejectingmassintotheinterstellarmediaofthese possibihty isthatthegaslostfromstarsresidesinaveryhot, of materialifthegalaxieshaveexistedforaHubbletime.One 0 extended halo(Forman,Jones,andTucker1985).Another is thattheonlynewstarsformareoflowmass(Jura plausible butnotcertainsinkforthegasejectedbyoldstars hot gas(CowieandBinney1977)mergerswithgas-rich mass lossfromstars(Ford1982),thevariousrolesofinfall 1977; SarazinandO’Connell1983).Finally,inadditionto be fullyelucidatedinunderstandingtheoriginof ob- companions (Knapp,Turner,andCunnifle1985)haveyet to served interstellarmatterinellipticalgalaxies. Rice, andtotheIPACstaff,fortheirconsiderablehelp with NSF. under theIRASextendedmissionprogramandpartlyby the Richstone andJ.Wrobel.Thisresearchwassupportedin part this work.Wehavereceivedusefulcommentsfrom D. Ford, H.C.1982,inIAUSymposium 103,PlanetaryNebulae,ed.D.R. Forman, W.,Jones,C,andTucker, W.H.1985,Ap.J.,293,102. Gallagher, J.S.1986, Pub.A.S.P.,98,81. We donotfullyunderstandtheoriginandevolutionofthis Flower (Dordrecht:Reidel),p.443. We aremostgratefultoDrs.T.Soifer,G.Helou,andW. Vol. 312 198 7ApJ. . .312L. .11J .1986a,Ap./.,306,483. .1986¿>,IrishAsir./.,inpress. Johnson, H.M.1966,Ann.Rev.Asir.Ap.,4,193. Jura, M.1977,Ap./.,212,634. Impey, C.D.,Wynn-Williams,G.,andBecklin,E.1986,Ap.J., Hansen, L.,Norgaard-Nielsen,H.U.,andJorgensen,E.1985,Astr. Mathews, W.G.,andLoewenstein,M.1986,Ap.J.{Letters),306,L7. Low, F.J.,etal.1984,Ap.J.{Utters),278,L19. Knapp, G.R.,Turner,E.L.,andCunniffe,P.1985,A.J.,90,454. Knapp, G.R.,andMorris,M.1985,Ap./.,292,640. Knapp, G.R.1986,Ap./.,inpress. Olofsson, H.1985,inWorkshoponSubmillimeterAstronomy,ed.P.A. No. 1,1987 M. JuraandD.W.Kim:DepartmentofAstronomy,UniversityCalifornia,LosAngeles,CA90024 08544 P. GuhathakurtaandG.R.Knapp:DepartmentofAstrophysicalSciences,PeytonHall,PrincetonUniversity,Princeton,NJ Ap., 149,442. 309, 572. Shaver andK.Kjar(Garching:EuropeanSouthernObservatory),p. © American Astronomical Society •Provided bythe NASAAstrophysics Data System INTERSTELLAR DUSTINSHAPLEY-AMESELLIPTICALS Wardle, M.,andKnapp,G.R.1986,A.J.,91,23. Wrobel, J.M.,Neugebauer,G.,andMiley,G.K.1986,Ap.{Letters), Tytler, D.1986,Ap.J.,mpress. Phillips, M.M.,Jenkins,C.R.,Dopita,A.,Sadler,E.andBinette, Sandage, A.,andTammann,G.A.1981,ARevisedShapley-AmesCata- Sadler, E.M.,andGerhard,O.1985,M.N.R.A.S.,214,177. Sadler, E.M.1984,A.J.,89,34. Sparks, W.B.,Wall,J.V.,Thome,D.J.,Jorden,P.R.,vanBreda,E.G., Soifer, B.T.,Rice,W.L.,Mould,J.R.,Gillett,F.C,Rowan-Robinson, Sarazin, C,andO’Connell,R.W.1983,Ap.J.,268,552. 309, Lll. logue ofBrightGalaxies(Washington:CarnegieInstituteWashing- L. 1986,A.J.,91,1062. Rudd, P.J.,andJorgensen,H.E.1985,M.N.R.A.S.,217,87. M. ,andHabing,H.J.1986,Ap.J.,304,651. ton). L15