Manuel Güdel ETH Zürich Switzerland

NeII

ESA

Star Formation on Stellar Scales

ManuelGüdelUniversityofVienna

Contents

Immediateenvironmentofformingstarisstronglycontrolledbyyoungstarandprocessedbythestellarradia8veoutput.

• Protoplanetarydisks:radia8onandspectrum• Protoplanetarydisks:Evolu8onanddispersal• Jets• Highenergyradia8on:ionisa8on,hea8ng,evapora8on• Summary

Circumstellar/protostellardustdisks:

Reflectedstarlight

or

silhoueEesagainstbrightbackground(OrionNebula)

(McCaughrean/O'Dell;STScI)

(Burrows/STScI/NASA)

Gas/dustmass≈100!

UsemminterferometryinCO:

Keplerrota8on!

CircumstellarGasDisks redshifted ≈ -1.2 km s-1

blueshifted ≈ 1.2 km s-1

HLTau

(Petyetal.2006)

(Simonetal.2000)

Spectralmodeling(I)–Diskstructure

ρ

M r

Gravityalongz:

Fz=GM/r2*z/rz

Forcebalance:‐∂P/∂z=Fz(forgas)

Scaleheight:H=5x10‐10T1/2r3/2[cm]<<r

(M=1Mo,moleculargas;"thin‐diskapproxima8on")

Spectralmodeling(II)–Disktemperature

op8callythick,flatdisk,equilibrium:influx=efflux∝σT4

→T(r)∝R*3/4Teff3/4r‐3/4

M Teff r

Blackbodyemission:σΤ4/π

ΔΩ

Thesamedependencyhappenstoholdforviscoushea8ng!

op8callythick,thermaldustfollowsblackbodyprescrip8onateveryposi8onwhereT=T(r):

Diskspectrum:

logSν

Rayleigh‐Jeans

Wien

logν

SEDgaps:diskholes?

Example:GMAur

hEp://www‐star.st‐and.ac.uk/~kw25/research/starform/gmaur/gmaur.html

op8callythinmmfrom100AUspectrum→diskmass

Observedspectralfall‐offisslower–diskiswarmer–diskismorestronglyirradiated–disk must be flared as suggested from scale‐height argument

Spectralmodeling(III)‐Diskstructureagain

FlareddiskH(r):T(r)∝r‐3/7closertospectralmodelingofobserva8ons:warmer disk, shallower fall‐off 

Disksdisappearrapidly:

(Hernandezetal.2008)

Simula8onofplanetforma8onbygravita8onalinstability

(Mayeretal.)

Problem:Directstellaraccre8onceasesaround0.2Mowhilediskaccre8onmustcon8nue.ButMdisk≈few%ofM*(observa8ons)

Howdoesma>erfurtheraccretefromdisktostar?

RiddleofVISCOSITY(internalfric8on):

Massflowsinwardbylosingangularmomentumwhichistransportedoutwardbyfric8on.

torquefromoutside

Magnetorota8onalInstability(MRI)specificangularm

omentum

7February2006

ALiEleAccre8onMachine:

→Ionisa8onAccre8onstream

MassAngularmomentum

Hea8ng

Wind

(Camenzind1990)

γ

→X‐rays

Diskwind:Centrifugalforcealongmagne8cfieldlines

"Slingshot"accelera8on→specificangularmomentumincreases

→Angularmomentumisdrawnfromdiskatfieldfootpoint:

J=mvr=mΩr2

→ACCRETION

Accre8onAngularmomentum

B m "rigid"

(net)

Jets

typicalouylowveloci8es≈ 300km/s

shocks,hea8ng

(NASA/A.Watson)

Evidenceforrota8ngjets:

(Dougadosetal.2000) (Baccio{etal.2000)

Wind‐upofmagne8cfieldlines(Montmerleetal.2000):

→ An8parallelmagne8cfields→ Hea8ngandReconnec8on→ Ejec8onofhotplasmaclouds→ Jets?Ouylowduetoaccre8on

(Hayashietal.1996)

Reconnec8on,Hea8ng,andJetForma8on

GlobalMagne8cFields:FromStartoInterstellarMedium

RadioPolarisa8on:

Magne:c fields  connect to ISM! 

(Rayetal.1997)

(~17’x17’)

NearInfrared(2MASS)X‐Rays(Chandra ACIS‐I):Garmireetal.1999

Trapezium+embeddedmassiveprotostars

(BN/KLRegion)

OrionNebulaCluster

(CourtesyofT.Montmerle/N.Grosso)

16.Mai2007

X‐rayobservatories

XMM‐Newton(ESA;1999):emphasisoneffec8veareasimultaneousimaging+spectroscopy

Chandra(NASA;1999):emphasisonangularandspectralresolu8on

3 Telescopes 58 concentric mirrors each

5 Cameras: 3 imaging 2 spectroscopic Optical Telescope

Röntgen

11m

16.Mai2007

Spectra:linesandcon8nuum

• temperatures::

• 30MK

• 10‐20MK

• 7MK

• 2MK

(XMM‐NewtonRGS)

30‘

Ionisa8onrateupto103‐1058meshigherthanbycosmicrayirradia8on.

Ionisa8ondegreefromstellarthermalX‐rays:

dominant out to >100 AU! 

(Igea & Glassgold 1999)  xcrit

for Magnetorotational Instability

Disk surface mid plane

Planet formation?

Accretion

LX =1029 erg s-1

(Ercolanoetal.2008)

ImpactonProtoplanetaryDisks:Hea8ngandIoniza8on

At1AUforstellarLX=2x1030ergs‐1,logT=7.2:

DisksurfacesareheatedtohightemperaturesbystellarX‐rays!

TemperatureIonisa8ondegree

(Ercolanoetal.2009)

Definewind(n,cs)atheightwherethermalenergy=poten8alenergy=escapespeed

GM/rg=kT/μmp=100AU(1000K/T)(M*/M)butevapora8ondownto0.15rgForT=10000K:rg≈1AU

EUV‐irradia:on:  en:re disk disappearson8mescalesof105yr

(Alexanderetal.2006)

ChandraACIS‐Simage,so�band(0.3‐1.5keV)

0.3”

T=1.8‐3.3MKvshock=350‐470kms‐1

DGTau

1pixel=0.0615”

Deconvolu8onofSER‐treatedACISdata(Güdel+2011)

2‐8keV

0.15”(33AUalongjet)

T=3.8MKvshock=500kms‐1

0.3‐1.5keVJET!

STAR

“lamp‐post" 

Shocks

X‐Rays

Disk

(HH111: B. Reipurth/HST/NASA)

HeaWng→photoevapora8on?

IonizaWon→Magnetorota8onalInstability?

(→Accre8on→Jets?...)

Relevant for disk dispersal and planet forma:on! 

MasslossratefromDGTaudiskdominatedbyjetirradia8onat

r>22AU

(Owenetal.inprep.)

jet absorbed star

…althoughthiswinddoesnotcompetewithaccre8on:

star:dM/dt≈3x10‐10Myr‐1

jet:dM/dt≈7x10‐10Myr‐1

12km/sperpendiculartodisk

(Pascucci & Sterzik 2009)

[NeII]

X‐RayViewoftheOrionNebula

IAUSpS7,Rio,12August2009

Photoevapora8onofProtostellarEnvironments?

far UV

103 K

Wind

EUV + X

Ionisation

NASA/J. Bally, H. Throop, C.R. O'Dell

T gradients → evaporation?

Summary

Stellarradia8onisfundamentallyimportantforevolu8onofcircumstellarmaEer–short‐wavelengthradia8oninpar8cular:

‐ diskprofile–irradia8ongeometry

‐ ionisa8on→magnetorota8onalinstability→accre8on→diskdispersal

‐ hea8ng→photoevapora8on→diskdispersal

‐ ionisa8on/hea8ng→drivingchemicalnetworks

Complexinterplaybetweencoolstuffandhotstuff!

End