天体物理讲座 恒星形成从太阳系附近到遥远的星系.pptVIP

Pontoppidanetal.2005,ApJ,inpressObservableSpectralEnergyDistributions(SEDs)大质量的恒星形成-Whyimportant?-Althoughfewinnumbers,LμM3theyinjectsignificantamountsofenergyintoISMduringtheirlifetime(outflows,radiation,supernovae).-Theyproducealltheheavyelements.-Low-massstarformationisstronglyinfluencedbymassivestars.-Massivestarsexclusivelyforminclusters.-ShortKelvin-Helmholtzcontractiontime:tKH=3x107yr(M*/1Ms)2(R*/1Rs)-1(L*/1Ls)-1For60Ms,12Rsand105.9Lswefind:tKH~11000yr--noobservablepre-mainsequenceevolution.-Radiationpressureimportantconstraint.二类形成模型Modifiedlow-massstarformation:Increaseaccretionratesafewordersofmag.2Ddiskgeometryhelpsaccretionprocesses.-Radiationpressurecanescapethroughoutflowcavities--flashlighteffectWolfireCassinelli1987,JijinaAdams1996,YorkeSonnhalter2002,NorbergMaeder2002,Keto2002,2003,Krumholzetal.2005,BanerjeePudritz2005Coalescenceandcompetetiveaccretion:-Massivestarsformonlyinclusters.Theclusterpotentialfavoursaccretiontowardobjectsintheclustercenters.-Allkindsofprotostellarentitiesmaymerge.Bonnelletal.1998,2004,2004,2007,Stahleretal.2000,BallyZinnecker2005PudritzBanerjee2005BallyZinnecker2005Bonnelletal.2007如果区分二者图像?分子外流和吸积盘.碎裂和整体塌缩.星系中的恒星极端形成不同的恒星形成率tracersHaX-rayUVRadiocontinuumInfrared,SpitzerTheytracesdifferentphysicalprocesses,andagreereasonablyObservedfar-IR/submmSEDsNon-thermalradioThermaldustDominatesluminosityHotterinAGN?SeeSpitzerMolecularandatomiclinesMmCO/HCNIR:C/N/O/H2IR:C=CPAH致密的冷气体tracersSubmmgalaxiesinCO(3-2),(4-3)Nerietal.ApJ(2003);IRAMinterferometer;sourceofdetectionsgivenonindividualframes8morenowhaveCOmeasurementsFrayeretal.N4Smailetal.N2.4Chapmanetal.Molecular