Lecture 16: Winds, Jets and Outflows

Lecture 16: Winds, Jets and OutflowsHH 212 H 2 (Mc Caughrean & Zinnecker VLT)

Losing Material from the Outer DiskThrough Photoevaporation

Formation & viscous spreading of disk

Formation & viscous spreading of disk

Formation & viscous spreading of disk

Photoevaporation of disks(Very brief)Ionization of disk surface creates surface layer of hot gas. Ifthis temperature exceeds escape velocity, then surfacelayer evaporates.v esc≈ GM 1/ 2⎛⎛ ⎞⎞⎜⎜ ⎟⎟⎝⎝ r ⎠⎠Evaporation proceeds for radii beyond:€r ≥ GM ≡ r2 grc sHII

The Edge of The Solar System:Evaporation of Disks by UV RadiationCenter of OrionNebulaHot O and B-typestars producepowerful UVradiation field.Young disk bathed inUV light.

Why is there an Edge to the Solar System:Evaporation of Disks by UV Radiation

Losing Material from the Inner Disk:through Accretion and Outflow9

Magnetospheric accretionFree-fall and accretion shockFrom r A down to star: matteris in supersonic free-fall.Accretion shockFree-fallregionNear the star the matter getsto a halt in a stand-off shock.r iShock velocity:v s=2GM 1− r *r *r iDissipated energy (=accretion luminosity from shock):⎛⎛L€accr= 1− r ⎞⎞*⎜⎜ ⎟⎟ G M ˙ M⎝⎝ ⎠⎠r ir *

Bipolar outflowsJets originatefrom innerregions ofprotoplanetarydisksHubble Space Telescope image

Magnetically threaded disksSuppose disk is treaded by magnetic field:Inward motion of gas in disk drags field inward:B-field aquiresangle with disk

€Disk windsSlingshot effect. Blandford & Payne (1982)(courtesy:C. Fendt)Use cylindricalcoordinates r,zGravitational potential:Φ = −GMr 2 + z 2Effective gravitationalpotential along field line (incl.sling-shot effect): €Φ = − GM ⎡⎡1 ⎛⎛⎢⎢ ⎜⎜r 0 ⎣⎣ ⎢⎢ 2 ⎝⎝rr 0⎞⎞⎟⎟⎠⎠2+r 0r 2 + z 2⎤⎤⎥⎥⎦⎦ ⎥⎥

Disk windsBlandford & Payne (1982)€Φ = − GM ⎡⎡1 ⎛⎛⎢⎢ ⎜⎜r 0 ⎣⎣ ⎢⎢ 2 ⎝⎝rr 0⎞⎞⎟⎟⎠⎠2+r 0r 2 + z 2Critical angle: 60 degreeswith disk plane. Beyondthat: outflow of matter.⎤⎤⎥⎥⎦⎦ ⎥⎥InfallOutflowGas will bend field lines

Disk + star: X-wind model of Frank ShuShu 1994

Different kinds of WindsFerreira, Dougados, Cabrit 2006Blandford & Payne 1982Konigl & Pudritz 2000Shu et al. 1994Matt & Pudritz 2005,…Configuration favorable for outflowsPirated from talk byMarina RomanovaBunching, α v > α d18

Magnetocentrifugal WindsRomanova et al. 2005; Ustyugova et al. 2006; Romanova et al. 2009

Jets or Winds?

Wind Blown Cavities

Bipolar Outflows driven by WindShu et al. 1991

Equations for core:Wind Blown BubbleEquations for wind:

Wind Blown Bubble

Wind Blown Bubble

Creating Jets

Creating Jets: Magnetic field winding - confinementC. Fendt

€Magnetic field winding - confinement(courtesy:C. Fendt)€j = c4π ∇ × Bf = 1 cj × BRight-hand rule:force pointsinwards

Hydrodynamic confinement in jet:Shock only reduces the velocity component perpendicularto shock front. Therefore obliquely shocked gas isdeflected toward the shock plane.

Hydrodynamic confinement in jet:

Bipolar outflows driven by JetsSwept-up material(molecular outflow)Terminal shockHydrodynamicconfinement?Hot bubble of old jet materialMagnetic confinementMagneto-centrifugallaunching (

Head of the jet:Turbulent mixing between old jetmaterial and swept-up environment(entrainment)Stand-off shock (most of jetenergy dissipated here)Contact discontinuity(boundary between jetand external medium)Back flowBow shockShocked external medium gas(molecular outflow)Jet flow much faster than propagation of bow shock.Jet material much more tenuous than external medium

Most Likely a Combination of Both

The Propeller RegimeDisk radius > Corotation Axis:Magnetic field rotating faster than diskUstyugova et al. 2006

Outflows at the Propeller Stage:Conical Winds + Axial JetA star spins-down due to axial magnetic jetPirated from talk by Marina Romanova23

Observed knot movement

Observations of Jets and Winds

Herbig-Haro ObjectsDiscovered independently by George Herbig and Guillermo Haroin 1950sSmall knots of nebulosity in dark cloudsDisplayed lines of hydrogen and forbidden lines of [OI], [NII] and[SII].Now known to be shock ionized nebulae.More than 400 Herbig Haro (HH) objects are known.Only trace a small fraction of the outflowing gas

Reipurth et al1989Forbidden Lines, Atomic HydrogenLines and Molecular Hydrogen LinesReipurth et al1989Carratti o Garatti et al. 2008

HH 111Knots are probably internal shocks, where faster knots are crashing intoslower knots[Fe II] + KHa + [SII]NICMOSWFPC2

HH 212 H 2 (Mc Caughrean & Zinnecker VLT)

HH 46/47 NTT [OΙΙ] Ηα [SΙΙ] = 0.38, 0.65, 0.67 µmBally & Reipurth (06 “Birth of Stars & Planets” CUP = BR06)

HH 46/47 Spitzer H 2 PAH 3.6, 4.5, 8 µm(Noriega-Crespo 04; BR06)

HST 1994HH 46/47(Hartigan et al. 05, AJBR06)

HST 1997HH 46/47(Hartigan et al. 05, AJBR06)

HH 2 HH 1HST 1997 - 1994

HH 2 HH 1HST 1997 - 1994

HH 1 jetHST 1997 - 1994

HH 1 jetHST 1997 - 1994

HH 1HST 1997 - 1994

HH 1HST 1997 - 1994

HH 2HST 1997 - 1994

HH 2HST 1997 - 1994

HH 34HST 1997 - 1994

HH 34HST 1997 - 1994

Molecular Outflows

MolecularOutflows:Line WingsBally & Lada1983

MolecularOutflows:BipolarityBally & Lada1983

Molecular Outflows: Basic PropertiesBally & Lada 1983

Molecular Outflows: Mechanical Luminosityand Momentum FluxBally & Lada 1983

MolecularOutflow: the“Hubble Law”NGC 2264 GFich & Lada1998

DistinguishingBow shockbetweenWind and JetModelsLee et al. 2001Wind

HH 288:Contours: CO(2-1)Greyscale: H 2

HH 211Contours: CO(2-1)

VLA 05487: example of wind (Lee et al. 2001)

DistinguishingBow shockbetweenWind and JetModelsLee et al. 2001Wind

HH 212: example of jet (Lee et al. 2001)

Detecting Jets in Molecular GasHH 211 jet

Detecting Jets in Molecular GasSiO mm-wave rotational lines are an excellent tracer of jets:abundance enhanced by a few orders of magnitude in jets

HH 211 Lee et al. 2007

SiO HH 212 Codella et al. 2008

HH212Lee etal.2007

HH 212 Lee et al. 2007