Massive star formation [Elektronische Ressource] : the role of disks / put forward by Cassandra Lorlene Fallscheer

DISSERTATIONSUBMITTEDTOTHECOMBINEDFACULTIESOFTHENATURALSCIENCESANDMATHEMATICSOFTHERUPERTO CAROLA UNIVERSITYOFHEIDELBERG,GERMANYFORTHEDEGREEOFDOCTOROFNATURALSCIENCESPUTFORWARDBYCASSANDRALORLENEFALLSCHEERBORNIN:CHICO,CALIFORNIA,USAthORALEXAMINATION:FEBRUARY9 ,2010MASSIVESTARFORMATIONTHEROLEOFDISKSREFEREES: PROF.DR.THOMASHENNINGPRIV.DOZ.DR.HENRIKBEUTHERDedicatedtothepeopleoftheKiwanisChicoCommunityObservatorywhotaughtmeto“keeplookin’up”.AbstractIn this thesis, I study three different evolutionary stages of the massive star formation pro cesslookingforsupportingevidenceforanaccretion basedformationscenarioofmassivestars.Thefirstsourcestudied,theInfraredDarkCloudIRDC18223 3,isatoneoftheearliestobserv ablephasesofmassivestarformation. Thissourceischaracterizedbyacone shapedmolecularoutflowcomponentwhichisusedtoestablishtheoutfloworientation. Avelocitygradienttraced+by the molecule N H but more convincingly by CH OH is indicative of a rotating object ori 2 3entedorthogonallytotheoutflowdirection. Thisobjectisontheorderof28,000AUinsizeanddoesnotexhibitKeplerianrotation,butmayhostadiskwithin. Modelingthisvelocitygradientshowsthatasinglerotatingandinfallingentityiscapableofreproducingtheobservations.Moving to a High Mass Protostellar Object, IRAS 18151 1208, a well defined outflow ori entation is observed as well as an elongation in the 1.3 millimeter dust continuum that is per-pendiculartotheoutflow.