Birth of Stars and PlanetsBen Brown June 2006 1Ben BrownBen BrownPleiadesPleiadesStar ClusterStar ClusterBirth of StarsBirth of StarsThurs 7 February 08Thurs 7 February 08ProtoplanetaryProtoplanetaryDisks in OrionDisks in Orionand Planetsand PlanetsStar and Planet BirthStar and Planet Birth••Look atLook athow stars are formedhow stars are formedout of out of big and cold molecular cloudsbig and cold molecular clouds••ExploreExplorehow young stars interacthow young stars interactwith their with their environmentsenvironments••Consider theConsider theformation of planetsformation of planetsin new in new solar systemssolar systemsSTAR BIRTHSTAR BIRTHwithin big cold cloudswithin big cold cloudsStart with clouds of Start with clouds of cold, interstellar gascold, interstellar gas••Molecular cloudsMolecular clouds----cold enough to form cold enough to form molecules T=10molecules T=10--30K30K••Often dustyOften dusty••Collapses under its Collapses under its own gravityown gravity••1.1.Collapse due to gravityCollapse due to gravityincreases the increases the temperaturetemperature. If thermal energy can escape via . If thermal energy can escape via radiation (glowing gas) ,radiation (glowing gas) ,collapse continuescollapse continues••2.2.If If thermal energy is trappedthermal energy is trapped, or more energy is , or more energy is generated due to fusion,generated due to fusion,collapse is slowedcollapse is slowedRecurring theme in forming stars:Recurring theme in forming stars:Conservation of Conservation of energyenergyand and angular momentumangular momentumCollapse from Collapse from Cloud to Cloud to ProtostarProtostar••First collapse fromFirst collapse fromvery large, cold cloudvery large, cold cloud––cold cold enough to contain molecules (molecular clouds)enough to contain molecules (molecular clouds)••The cloud fragments intoThe cloud fragments intostarstar--sized massessized masses••Temperature increasesTemperature increasesin each fragment as it in each fragment as it continues to collapsecontinues to collapseBirth of Stars and PlanetsBen Brown June 2006 2Dusty, dark molecular cloud regionsBlack Cloud B58 ESOBlack Cloud B58 ESOStar birth in Star birth in ScorpiusScorpiusAATAATStellar nurseriesStellar nurseriesstart as cold placesstart as cold placesGiant Molecular CloudStar Forming CoreAccretion Disks + Proto-StarsGravity, Spin, Magnetic FieldsRotating CoreGravityDisksJetsCollapse from large, cold cloudConservation of Angular Momentum: material spins fasterDisks and Jets formaround protostarCollapsing cloudCollapsing cloudspins upspins up, forms, formsstar, disk and jetstar, disk and jetHST: actual edgeHST: actual edge--on disk, jeton disk, jetJets from young stellar objects (Jets from young stellar objects (YSOsYSOs))Birth of Stars and PlanetsBen Brown June 2006 33 3 ÆÆ4:4:As core temperatures reach millions of degrees, As core temperatures reach millions of degrees, fusion begins and stabilizes fusion begins and stabilizes ––star joins main sequencestar joins main sequenceOGMGalaxy colorGalaxy color••1 blue O 1 blue O ÆÆ100 red M100 red M••LumLumO = 10,000 solar O = 10,000 solar luminositiesluminosities••LumLumM = 0.001 solar M = 0.001 solar luminositiesluminosities••What color is the What color is the starlight from thestarlight from thestar forming spiral armsstar forming spiral armsin our galaxy?in our galaxy?••A. BlueA. Blue••B. OrangeB. Orange••C. RedC. RedOGMGalaxy colorGalaxy color••A. BlueA. Blue• 100 times more M stars, but each is 10,000,000 times fainterthan an O star• Massive blue stars dominate the light••Hot newHot newbluebluemain main sequence starssequence stars••PinkPinkhydrogen gashydrogen gas••BlackBlacksooty dustsooty dust••Blue nebulae are Blue nebulae are reflections of reflections of starlight from starlight from massive blue starsmassive blue starsStellar nurseries yield lovely sightsStellar nurseries yield lovely sightsThe Orion Star Forming ComplexBirth of Stars and PlanetsBen Brown June 2006 4Infrared view of winter sky (10 - 120 µm)IRIROrion NebulaOrion MolecularCloudsCarbon Monoxidemeasurementsapproaching usrecedingHST 16HST 10HST 17Irradiated proto-planetary disks in OrionEagle NebulaEagle Nebula: cold dark : cold dark clouds are eroded by clouds are eroded by intense starlightintense starlightHST iconHST iconHubble Space TelescopeSpitzer Space TelescopeESO Very Large TelescopeSimulations by:Matthew Bate, U Exeter (stellar formation)N-Body Shop, UW (planet formation)The Cosmic Perspective TextbookThe Birth of Stars and PlanetsJohn BallyTravis Rector Davide De MartinImages from:Thanks toJohn BallyFrancisco SalasKris SpindenDavid StaggGwen