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co-ti-ta三元系富co区的相平衡
phase equilibria in co-rich region of co-ti-ta sys.
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内容提示：co-ti-ta三元系富co区的相平衡
phase equilibria in co-rich region of co-ti-ta system
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co-ti-ta三元系富co区的相平衡
phase equilibria in
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tools:ignore=&MissingTranslation&&&/resources&39Absorption-Line Probes of Gas and Dust in Galactic Superwinds
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39Absorption-Line Probes of Gas and Dust in Galactic Superwinds
Absorption-LineProbesofG；TimothyM.Heckman1；DepartmentofPhysicsandAs；3400NorthCharlesStreet,B；MatthewD.Lehnert1；Max-Plank-Institutf¨urex；Germany；DavidK.Strickland；DepartmentofPhysic
.Absorption-LineProbesofGasandDustinGalacticSuperwindsTimothyM.Heckman1DepartmentofPhysicsandAstronomy,JohnsHopkinsUniversity,HomewoodCampus,3400NorthCharlesStreet,Baltimore,MD21218MatthewD.Lehnert1Max-Plank-Institutf¨urextraterrestrischePhysik,Postfach1603,D-85740Garching,GermanyDavidK.StricklandDepartmentofPhysicsandAstronomy,JohnsHopkinsUniversity,HomewoodCampus,3400NorthCharlesStreet,Baltimore,MD21218andLeeArmus1SIRTFScienceCenter,310-6,Caltech,Pasadena,CA91125arXiv:astro-ph/
29 Feb 20001.Visitingastronomers,KittPeakNationalObservatoryandCerroTololoInteramericanObservatory,NOAO,operatedbyAURA,Inc.undercooperativeagreementwiththeNationalScienceFoundation.ABSTRACTWehaveobtainedmoderateresolution(R=afewthousand)spectraoftheNaIλλ(NaD)absorption-lineinasampleof32far-IR-brightstarburstgalaxies.In18cases,theNaDlineinthenucleusisproducedprimarilybyinterstellargas,whilecoolstarscontributesigni?cantlyintheothers.In12ofthe18“interstellar-dominated”casestheNaDlineisblueshiftedbyover100kms?1relativetothegalaxysystemicvelocity(the“out?owsources”),whilenocaseshowsanetredshiftofmorethan100kms?1.Theabsorption-linepro?lesintheseout?owsourcesspantherangefromnearthegalaxysystemicvelocitytoamaximumblueshiftof～400to600kms?1.Theout?owsourcesaregalaxiessystematicallyviewedmorenearlyface-onthantheothers.Wethereforearguethattheabsorbingmaterialconsistsofambientinterstellarmaterialthathasbeenentrainedandacceleratedalongtheminoraxisofthegalaxybyahotstarburst-drivensuperwind.TheNaDlinesareoptically-thick,butindirectargumentsimplytotalHydrogencolumndensitiesofNH～few×1021cm?2.Thisimpliesthatthesuperwindisexpellingmatterataratecomparabletothestar-formationrate.Thisout?owingmaterialisevidentlyverydusty:we?ndastrongcorrelationbetweenthedepthoftheNaDpro?leandtheline-of-sightreddening.TypicalimpliedvaluesareE(B?V)=0.3to1overregionsseveral-to-tenkpcinsize.Webrie?yconsidersomeofthepotentialimplicationsoftheseobservations.TheestimatedterminalvelocitiesofsuperwindsinferredfromthepresentdataandextantX-raydataaretypically400to800kms?1,areindependentofthegalaxyrotationspeed,andarecomparableto(substantiallyexceed)theescapevelocitiesforL?(dwarf)galaxies.Theresultingselectivelossofmetalsfromshallowerpotentialwellscanestablishthemass-metallicityrelationinspheroids,producetheobservedmetallicityintheintra-clustermedium,andenrichageneralIGMtoof-order10?1solarmetallicity.Iftheout?owingdustgrainscansurvivetheirjourneyintotheIGM,theire?ectonobservationsofcosmologically-distantobjectswouldbesigni?cant.Subjectheadings:galaxies:starburstCgalaxies:nucleiCgalaxies:activeCgalaxies:ISMCgalaxies:kinematicsanddynamicsCgalaxies:halosCgalaxies:intergalacticmediumCgalaxies:evolutionCinfrared:galaxiesCISM:dust,extinction1.IntroductionBynow,itiswell-establishedthatgalactic-scaleout?owsofgas(sometimescalled‘superwinds’)areaubiquitousphenomenoninthemostactivelystar-forminggalaxiesinthelocaluniverse(Heckman,Lehnert,&Armus1993;Dahlem1997;Bland-Hawthorn1995).Theyarepoweredbytheenergydepositedintheinterstellarmediumbymassivestarsviasupernovaeandstellarwinds.Overthehistoryoftheuniverse,out?owslikethesemayhavepollutedtheintergalacticmediumwithmetals(e.g.Giroux&Shull1997)anddust(Alton,Davis,&Bianchi1999;Aguirre1999a,b),heatedandpollutedtheintraclustermedium(e.g.Gibson,Loewenstein,&Mushotzky1997;Ponman,Cannon,&Navarro1999),andmayhaveestablishedthemass-metallicityrelationandradialmetallicitygradientsingalacticspheroids(e.g.Carollo&Danziger1994).However,theastrophysicalrelevanceofsuperwindscannotbereliablyassessedwithout?rstunderstandingtheirphysical,dynamical,andchemicalproperties.Todate,mostofthepertinentinformationhascomefromobservationsoftheX-rayemissionproducedbythehotgas(e.g.Dahlem,Weaver,&Heckman1998)ortheopticalline-emissionproducedbythewarmgas(e.g.Lehnert&Heckman1996a).Inthepresentpaper,wetakeacomplementaryapproach,anddiscussanextensivebodyofnewdatathatprobestheout?owinggasviaitsinterstellarabsorption-lines.Thistechniquehassomeimportantadvantages.First,sincethegasisseeninabsorptionagainstthebackgroundstarlight,thereisnopossibleambiguityastothesign(inwardsoroutwards)ofanyradial?owthatisdetected.Second,thestrengthoftheabsorptionwillberelatedtothecolumndensityofthegas.Incontrast,theX-rayoropticalsurface-brightnessoftheemittinggasisproportionaltotheemission-measure.Thus,theabsorption-linesmorefullyprobethewholerangeofgasdensitiesintheout?ow,ratherthanbeingstronglyweightedinfavorofthedensestmaterial(whichmaycontainrelativelylittlemass).Finally,providedthatsuitably-brightbackgroundsourcescanbefound,interstellarabsorption-linescanbeusedtostudyout?owsinhigh-redshiftgalaxieswheretheassociatedX-rayoropticalemissionmaybeundetectablyfaint.Thispromisehasalreadybeenrealizedinthecaseofthe’LymanDropout’galaxies,wherethekinematicsignatureofout?owsisclearintheirrest-frameUVspectra(Franxetal1997;Pettinietal).Afewpioneeringstudieshavealreadydetectedinterstellarabsorption-linesfromsuperwindsinlocalstarburstgalaxies.Phillips(1993)discussedspatially-resolvedopticalspectroscopyoftheNaI“D”doubletinNGC1808,showingthatanout?owofgasatvelocitiesofupto700kms?1couldbetracedoveraregionseveralkpcinsize,coincidentwitharegionofextra-planardustplumes.Severalrecentpapers(Lequeuxetal.1995;Heckman&Leitherer1997;Sahu&Blades1997;Kunthetal.1998;Gonzalez-Delgadoetal1998a)havedetectedblueshiftedinterstellarabsorption-linesinHSTandHUTUVspectraofahandfulofstarburstgalaxies,implyingout?owsofmetal-bearinggasatvelocitiesof102to103kms?1.Mostofthestrongresonancelinesofcosmically-abundantionsarefoundintheUV(e.g.Morton1991;Savage&Sembach1996),andsomustbestudiedwithHSTorFUSEinlocalstarbursts.Inthepresentprogram,wehaveinsteadexploitedtherelativelygreatersensitivityandavailabilityofground-basedtelescopesatvisiblewavelengthstostudyalargesampleofstarbursts/superwindsusingtheNaIdoubletatλλ?A.Inafewcases,wehavealsoobservedtheKIλλ?Adoublet,sinceitprobesgaswithnearlythesameionizationstateasNaI,butismorelikelytobeopticallythin(theKabundanceisdownfromNabyafactorof15,whilethetwodoubletshavesimilaroscillatorstrengths).TheionizationpotentialsofNaIandKIareonly5.1eVand4.3eVrespectively,sothesespeciesshouldprimarilyprobetheHIandH2ISMphases.Observationsinvacuum-UVwillberequiredtostudythehotterandmorehighlyionizedgasinabsorption.2.2.1.TheDataSampleSelectionTable1liststhesalientpropertiesofthe32objectsinoursample.Theseobjectshavebeendrawnfromthelargersamplesofinfrared-selectedgalaxiesstudiedbyArmus,Heckman,&Miley(1989-hereafterAHM)andbyLehnert&Heckman(1995-hereafterLH95).Thespeci?cselectioncriteriausedintheseintwoprogramsaredescribedindetailinthesereferences.Brie?y,AHMselectedonthebasisoffar-IR?uxandverywarmfar-IRcolor-temperatures.LH95selectedonthebasisoffar-IR?ux,moderatelywarmfar-IRcolor-temperatures,andhighgalaxyinclination(diskgalaxiesseenwithin～30?ofedge-on).TheAHMandLH95samplesoverlapingalaxyproperties,buttheformerpreferentiallyselectsmorepowerfulandmoredistantobjects.AHMmeasuredtheequivalentwidthsoftheNaDlinesintheirsampleusinglow-resolutionspectra.ThegalaxiesfromAHMwereselectedforthepresentprogramonthebasisofthebrightnessoftheirnucleusat～5900?AandtheequivalentwidthofNaD.ThegalaxiesfromLH95hadnopriormeasuresoftheNaDline,andwereselectedbasedprimarilyontheirproximityandavailabilityatthetimeoftheobservations.Ofthe32objects,only3areclassi?edasbona?deAGNofthebasisoftheiropticalspectra:thetype2SeyfertsNGC7582andMrk273andthehighlypeculiarAGNIRAS.Nopublishedclassi?cationexistsforIRAS.Theremainingobjectsareopticallyclassi?edasHIInucleiorLINER′s,andarepresumedtobeprimarilypoweredbydustystarbursts(Lutz,Veilleux,&Genzel1999).EvenintheSeyfertgalaxiesNGC7582andMrk273,opticalspectrashowthepresenceofayoungstellarpopulationinthenucleus(Schmitt,Storchi-Bergmann,&Cid-Fernadez1999;Gonalzez-Delgado,Heckman,&Leitherer2000).Thus,withthepossibleexceptionofIRASandIRAS,theobjectsinoursampleallcontainpowerfulstarburststhatcandrivesuperwinds.2.2.ObservationsTheobservationswereundertakenduringtheperiodfrom1988through1994usingthreedi?erentfacilities:the4-meterBlancoTelescopewiththeCassegrainSpectrographatCTIO,the4-meterMayallTelescopewiththeRCSpectrographatKPNO,andthe2.5-meterDupontTelescopewiththeModularSpectrographattheLasCampanasObservatory.Variousspectrographcon?gurationswereusedateachobservatory,thedetailsofwhicharelistedinTable2.ThespectralresolutionusedtostudytheNaDlinesrangedfrom55to170kms?1.Whilelowbythestandardsofinterstellarabsorption-linestudies,theresolutionwasgoodenoughtocleanlyresolvetheNaDlinesinmostcases(deconvolvedlinewidthsof100to600kms?1-seebelow).2.3.DataReduction&AnalysisThespectrawereallprocessedusingthestandardLONGSLITpackageinIRAF.Allthedatawerebias-subtractedusingtheoverscanregionofthechipandthen?at-?eldedusingobservationsofeitheraquartz-lamp-illuminatedscreeninsidethedomeorofaquartzlampinsidethespectrograph.Thespectrawerethenrecti?edusingobservationsofbrightstarstodetermineandremovethedistortionperpendiculartothedispersiondirectionandobservationsofaHeNeArarclamptodeterminethetwo-dimensionaldispersionsolution.Thezero-pointsinthewavelengthscalewereveri?edbymeasuringthewavelengthsofstrongnight-skyemission-lines.Correctionstotheheliocentricreference-framewerecomputedforthespectra.Thespectrawerethensky-subtractedbyinteractively?ttingalow-orderpolynomialalongthespatialdirection,column-by-column.Forafewofthegalaxiesweobtainedrelativelylow-dispersionspectrathatwillbeusedtomeasurethereddening(Balmerdecrementandcontinuumcolor).Thesedatawere?ux-calibratedusingobservationsofspectrophotometricstandardstars,andotherwisewerereducedinthesamewayastheotherdata.包含各类专业文献、外语学习资料、生活休闲娱乐、各类资格考试、专业论文、幼儿教育、小学教育、中学教育、39Absorption-Line Probes of Gas and Dust in Galactic Superwinds等内容。　}