Photoevaporation of Protoplanetary Disks

Photoevaporation of protoplanetary disks

Sabine Richling Institut d’Astrophysique de Paris

EC Research Training Network“PLANETS” http://www.usm.uni-muenchen.de/Planets/ Outline

• Photoevaporation of clouds and disks • Observational properties of the proplyds in M42 • Proplyd candidates in other star forming regions • (Semi-)Analytical models for proplyds – general structure of proplyds – photoevaporation rate • Two-dimensional numerical simulations – physics involved – formation of tails and jets – time-dependent photoevaporation rate • Photoevaporation from inside • Importance of other disk dispersal mechanisms • Consequences for the formation of the solar system The photoevaporation process

hydrogen ionizing radiation

evaporating ~ 10 000 K flow Ionisation front 10 ... 100 K

• UV photons (hν>13.6 eV) reach surface of dense material • UV photons ionize hydrogen and heat the region behind the advancing ionization front up to ∼ 104 K • hot material expands → evaporating ﬂow Photoevaporation of molecular clouds

Eagle Nebula M16

• dense molecular clouds at border of HII region

• structure of the evaporating ﬂow: n ∝ d−2 n: density of the ﬂow d: distance from ionization front

• strong free-free emission and emission in forbidden lines close to the ionization front

• ionization front traces cloud surface Photoevaporation of protoplanetary disks

Orion Nebula M42

• UV photons from Trapezium Cluster

• Emission lines: Hα → green [NII] → red [OI] → blue

• Photoevaporating disks appear as head-tail objects (proplyds)

• tails are pointing away from main ionizing star θ1 Orionis C

Bally et al. (1998) The acronym

PROPLYDS = PROtoPLanatarY DiskS

Protoplanetary disks made visible by being in or in front of an H II region.

(O’Dell, Wen & Hu 1993)

Two types of proplyds: “protoplanetary disks being in an HII region”→ proplyds (star-disk system + head-tail envelope) “protoplanetary disks being in front of an HII region”→ dark proplyds, silhouette disks

Other propositions: PIGS = Partially Ionized GlobuleS (Dopita et al. 1974, Garay 1987) EIDERS = Externally Ionized Disks in the Environs of Radiation Sources (Felli et al. 1993) Proplyds in the Orion Nebula

Bally et al. (1998) Properties of the Orion proplyds

• first detection of 6 nebulosities (Laques & Vital 1979) → LV objects • radio continuum (VLA) (Garay et al. 1987, Churchwell et al. 1987, Felli et al. 1993) 6 −3 → compact radio sources with ne ∼ 10 cm • IR images (McCaughren & Stauffer 1994) → IR sources within the proplyds • optical images (HST: O‘Dell et al. (1993), O’Dell & Wong (1996); adaptive optic: McCullough et al. (1995)) → head-tail structure, orientation towards UV source • Chen et al. (1998) (HST) → disk-like H2 emission → stand-off of ionization front • Bally et al. (1998, 2000) (HST) → dark silhouettes within the proplyds (30%) → tail length 100 - 1700 AU, limb brightened → micro-jets, [0III] arcs • Spectroscopic observations (Maebuern et al. 2002, de la Fuente et al. 2003) → velocity in the ionized flow: ∼ 20 km/s → velocity of the micro-jets: ∼ 100 km/s Proplyd HST 10

Hα, [OIII], [NII]: → ionized envelope in emission → disk in absorption

[OI], molecular hydrogen: → disk in emission

→ stand-oﬀ of ionization front Johnstone et al. (1998) Orion proplyds in Hα

Bally et al. (2000) Micro-jet in proplyd 282-458 (HH527)

→ one-sided micro-jet → rotation axis 6= direction of UV source

Bally et al. (2000) More micro-jets in Orion proplyds

Bally et al. (2000) [OIII] arcs – Wind interaction

• Interaction of stellar wind with evaporating ﬂow from proplyd head

• Position of shock front is deﬁned by pressure equilibrium between both ﬂows Bally et al. (1998) Binary proplyd LV1 – Interaction between winds from proplyds

[OIII] λ 5007 image (high and low resolution)

HST Hα image and MERLIN 5 GHz contours

Graham et al. (2002) Proplyds in the Orion Nebula

Orion Nebula M42

Main ionizing source: O6 star θ1 Orionis C

5 Luminosity: Lbol ∼ 10 L 49 −1 UV photon rate: SUV = 1.5x10 s

14 12 5 arcsec = 0.01 pc 10 8 6 4 number of proplyds 2 0 0 20 40 60 80 100 projected distance [arcsec] Bally et al. (1998) Proplyd candidates in NGC 3603

Proplyd 3 N

Proplyd 1 E Giant HII Region NGC 3603

Proplyd 2 Ionizing source: compact massive cluster (>4000 M ) with ∼70 O-type stars and 3 WR stars

7 Luminosity: Lbol > 10 L 51 −1 UV photon rate: SUV = 10 s

Proplyd distance from cluster

Proplyd 1: HST + VLT/ISAAC Bow shocks? # pc 1 1.3 2 2.2 1 parsec 33" 3 2.0

Brandner et al. (2000) Proplyd candidates in the Carina Nebula

Carina Nebula NGC 3372

Ionizing source: several clusters of young massive stars ∼60 O-type stars + η Car (LBV)

7 Luminosity: Lbol ∼ 10 L 51 −1 UV photon rate: SUV ∼ 10 s

Distance from UV source: ∼ 0.1 pc

Smith et al. (2003) Comparison of proplyds in diﬀerent environments

star formation region proplyds name distance UV photon rate distance tail size mass loss rate −1 -1 kpc s pc AU M yr

Orion M42 0.43 1049 0.01–0.15 ∼ 500 ∼10−7

Carina Nebula 2.3 1051 ∼ 0.1 < 10 000 ∼10−5

NGC 3603 6 1051 1.3–2.2 ∼ 20 000 ∼10−5

Possible reasons for diﬀerence in size: • selection eﬀect • larger disks, only recently separated from clouds • FUV/EUV ratio very high External UV illumination

massive star

too simple ! UV radiation

ionization front

circumstellar disk

• Hydrogen ionization front directly envelopes the disk • Lifetime of tails is very short (∼ 104 yr) External UV illumination

massive star

EUV radiation (> 13.6 eV) HI/HII front

FUV radiation PDR (6 − 13.6 eV) circumstellar CI/CII front disk Simple PDR model

PDR = PhotoDissociation Region or Photon-Dominated Region

CI/CII front HI/HII front dissoziation fronts

HI HII H 2

FUV OII + OI OIII FUV EUV CO NII CII

HII region PDR molecules (10 000 K) (1000 K) (10−100 K)

PDR heating mechanisms: photo-electric eﬀect on dust grains, ionization of C, dissociation of molecules PDR cooling mechanisms: OI 63 µm, CII 158 µm, H2 lines Important radii

Gravitational radius Rg Truncation radius Rt thermal velocity = escape velocity pressure of advancing ionization front = GM midplane pressure in disk Rg = cs Rt ∼ 300 AU Rg ∼ 10 AU (for M = 0.5 M , Md = 0.1 M , −1.5 (for M = 1 M and cs = 3 km/s) surface density proﬁle ∝ r )

R g R t

evaporating flow

circumstellar disk Radius FUV dominated ﬂows

„ «„ « −8 −1 Nd rd M˙ FUV = 2 × 10 M yr 5 × 1021 cm−2 10 AU

Nd: gas column density of the neutral region (τFUV ∼ 1)

(Johnstone et al. 1998, St¨orzer & Hollenbach 1999) EUV dominated ﬂows

„ «0.5 „ «−1 „ «1.5 −9 −1 ΦEUV d rd M˙ EUV = 7 × 10 M yr 1049 s−1 1017 cm 10 AU

ΦEUV: EUV photon rate d: distance to the UV source

(Johnstone et al. 1998, St¨orzer & Hollenbach 1999) Photoevaporation rate and the lifetime of disks

Orion Nebula Lifetime of disks ˙ rd = 20 – 100 AU and d = 0.01 – 0.15 pc Photoevaporation time scale: τ = Md/M ˙ −7 −6 −1 → Mtheory = 10 – 10 M yr But: disk radius is not constant

Assumption: surface density Σ ∝ r−1.5

Md(current) = Mt˙ i 5 Illumination time ti < 10 yr

for Md(current) = 0.01 M Small in comparison of cluster age ∼ 106 yr (Johnstone et al. 1998)

Uncertain:

• disk evolution: Σ(r, t), rd(t) • orbits of low-mass stars in cluster: d(t) • contribution of the dark side of the disk 2 Estimated from: M˙ obs ∼ πr mHnec (Henney & O’Dell 1999) A model for proplyds – The whole picture

• disks at any angle, disks with jets • formation and evolution of tails → Numerical simulations • interaction with external stellar winds • spectral appearance of photoevaporating disks Numerical simulations – Physics

circumstellar disk

• Hydrodynamics • hydrodynamics • self-gravity • angular momentum transfer • continuum radiation transfer Numerical simulations – Physics

massive star

EUV radiation (> 13.6 eV) HI/HII front

circumstellar disk

• Hydrodynamics • transfer of direct EUV photons • transfer of diﬀuse EUV photons • EUV radiation • ionization/recombination of hydrogen • heating/cooling (HII region) Numerical simulations – Physics

massive star

EUV radiation (> 13.6 eV) HI/HII front

FUV radiation PDR (6 − 13.6 eV) circumstellar CI/CII front disk

• Hydrodynamics • transfer of direct FUV photons • transfer of diﬀuse FUV photons • EUV radiation • ionization/recombination of carbon • FUV radiation • heating/cooling (PDR) Hydrodynamics and continuum radiative transfer

Equation of continuity: ∂ρ ∂ + (ρvi) = 0 ∂t ∂xi Equation of motion: ∂ ∂ ∂p ∂Φ ∂Tij κFi (ρvi) + (ρvivj) = − − ρ + ρ + ρ ∂t ∂xj ∂xi ∂xi ∂xj c Energy equation: ∂e ∂ ∂vi ∂vi + (evi) = −p + ρTij − Λgas−dust+(Γ − Λ)UV ∂t ∂xi ∂xi ∂xj Equation of state: p = p(ρ, e)

Poisson equation: ∆Φ = 4πGρ

Radiative transfer (dust continuum, grey approximation, isotropic point source):  ∂Fi at position of point source = ∂xi 0 elsewhere Direct UV radiation

Transfer equation for integration along lines of sight: ext ∇ · Fstar = −χstarFstar

Extinction coeﬃcient for EUV photons: ext ext χstar = n(1 − x)σstar + κdust

Extinction coeﬃcient for FUV photons: ext FUV ext χstar = nC(1 − xC)σC + κdust

Solution for spherical symmetry: Z Sstar ext Fstar = exp(−τ) mit τ = χ ds 4πr2 star Diﬀuse UV radiation

Flux-limited diﬀusion (FLD) approximation (Levermore & Pomraning 1981):

λc F = − ∇u χext Flux-limiter:

1 „ 1 « |∇u| λ = coth S − and S = S S χextu Advantage: ( c∇u for S → ∞ (optically thick) 3χext F → ∇u cu · |∇u| for S → 0 (optically thin) Diﬀuse UV radiation

∂u „ λc « − ∇ · ∇u = − χabscu ∂t χext

EUV: Recombination of hydrogen into the ground state: 2 2 rec = α(Tgas)n x ext ext χrec = n(1 − x)σrec + κrec abs abs χrec = n(1 − x)σrec + κrec

EUV: Scattering on dust grains: scat EUV dust = κdustcustar , ext ext χdust = n(1 − x)σstar + κdust abs abs χdust = n(1 − x)σstar + κdust

FUV: Scattering on dust grains: scat FUV dust = κdustcustar ext FUV ext χdust = nC(1 − xC)σC + κdust abs FUV abs χdust = nC(1 − xC)σC + κdust Ionization/Recombination

Rate equation for the degree of ionization of hydrogen x:

photoionization (only EUV photons)

∂ρx EUV EUV EUV + ∇ · (ρxv) = ρ(1 − x)[σstaru +σrecu +σstaru ]c ∂t star rec dust 2 +ρC(T )nx(1 − x) − ραA(T )nx collisional ionization recombination

Rate equation for the degree of ionization of carbon xC:

photoionization (EUV and FUV photons)

∂xC h FUV FUV FUV EUV EUV EUV EUV i = (1 − xC) σ (u + u ) + σ (u + u + u ) c ∂t C star dust C star rec dust −αCxCne recombination Heating/Cooling

region main heating mechanism main cooling mechanism

HII region photoionization radiative cooling [OIII],[OII],[NII]

Γ = n(1 − x)σcu[hhνiσ − 13.6 eV] Λνij = niAijhνij

PDR photo-electric eﬀect radiative cooling on dust grains [OI],[CII]

−24 −1 Γ = 10 η G0 n erg s Λ = niAijhνijβesc(τij)

η(T,G0, ne): eﬃciency βesc: escape probability Numerical methods

RHD-Program EXTERN

RHD-Package Grid architecture and lines of sight arrangement

explicit 2D hydrodynamics (method of nested grids) Z star angular momentum transfer self-gravity wind generator for stellar wind continuum radiation transfer Z (R 1 ,Z 1 ) EUV-Package

transfer of direct EUV photons along lines of sight (R 2 ,Z 2 ) transfer of diffuse EUV photons (recombination of H) transfer of diffuse EUV photons (dust scattering)

ionization/recombination of H

heating/cooling (T ¡ 10000 K) R

FUV-Package

transfer of direct FUV photons along lines of sight transfer of diffuse FUV photons (dust scattering)

ionization/recombination of C

heating/cooling (T ¡ 1000 K) Initial star-disk models

Results from collapse simulations (e.g. Yorke & Bodenheimer 1999):

−1 Time[Tff] 2.5 vnorm [km s ] 5 170

−10

85 ]

−12 −3

[g cm [g Z [AU] Z

−14 ρ log log

−85 −16

−170 −200 −100 0 100 200 R [AU] External UV illumination – Evolution

-1 -1 -1 Time [yr] 135 vnorm [km s ] 10 Time [yr] 1452 vnorm [km s ] 30 Time [yr] 26336 vnorm [km s ] 40

2000 2000 2000 -20 -20 -20

0 0 0 -18

-18 ] ] -18 ] -3 -3 -3 [g cm [g cm [g cm

-2000 ρ -2000 ρ -2000 ρ Z [AU] Z [AU] Z [AU]

log -16 log log -16 -16

-4000 -4000 -4000

-14 -14 -14

-6000 -6000 -6000 -2000 0 2000 -2000 0 2000 -2000 0 2000 R [AU] R [AU] R [AU]

-1 -1 -1 Time [yr] 59243 vnorm [km s ] 40 Time [yr] 88763 vnorm [km s ] 40 Time [yr] 130582 vnorm [km s ] 40 -22 Sequence 3302 Sequence 3302 Sequence 3302 2000 2000 -22 2000 -22 Model 100 Model 1000 Model 22000

Mstar/Msun 0.58 Mstar/Msun 0.58 Mstar/Msun 0.58 -20 Mdisk/Msun 0.42 Mdisk/Msun 0.41 -20 Mdisk/Msun 0.25 -20 0 0 0 ] ] ] -3 -3 -3 -18 -18 -18 [g cm [g cm [g cm

-2000 ρ -2000 ρ -2000 ρ Z [AU] Z [AU] Z [AU] log log log

-16 -16 -16

-4000 -4000 -4000

-14 -14 -14

-6000 -6000 -6000 -2000 0 2000 -2000 0 2000 -2000 0 2000 R [AU] R [AU] R [AU]

Sequence 3302 Sequence 3302 Sequence 3302 Model 51000 Model 74000 Model 105500

Mstar/Msun 0.58 Mstar/Msun 0.58 Mstar/Msun 0.58

Mdisk/Msun 0.15 Mdisk/Msun 0.09 Mdisk/Msun 0.05 External UV illumination – Head of object

Density Temperature

Time [yr] 59243 v [km s-1] 25 norm Time [yr] 59243

500 500

2000 -18

0 0 ] -3 4000 [g cm T [K]

-16 ρ Z [AU] Z [AU]

-500 log -500

6000

-14 -1000 -1000

8000

-500 0 500 -500 0 500 R [AU] R [AU]

Sequence 3302

Model 51000

Mstar/Msun 0.58

Mdisk/Msun 0.15 Comparison with observations – Emission lines

[OII] 3726 30o [OII] 3726 60o [OII] 3726 90o [OII] 3726 120 o [OII] 3726 150 o

-0.5 1 -0.5 1 -0.5 1 -0.5 1 -0.5 1

0 0 0 0 0 -1.0 -1.0 -1.0 -1.0 -1.0 -1 -1 -1 -1 -1 -1.5 -1.5 -1.5 -1.5 -1.5 Z [1000 AU] Z [1000 AU] Z [1000 AU] Z [1000 AU] Z [1000 AU] -2 -2 -2 -2 -2 -2.0 -2.0 -2.0 -2.0 -2.0 -3 -3 -3 -3 -3

-4 -2.5 -4 -2.5 -4 -2.5 -4 -2.5 -4 -2.5

-2 -1 0 1 o 2 -2 -1 0 1 o 2 -2 -1 0 1 o 2 -2 -1 0 1 o 2 -2 -1 0 1 o 2 [OIII]R 5007[1000 AU] 30 [OIII]R 5007[1000 AU] 60 [OIII]R 5007[1000 AU] 90 [OIII]R 5007[1000 AU] 120 [OIII]R 5007[1000 AU] 150 0.0 0.0 1 1 0.0 1 0.0 1 0.0 1

0 -0.5 0 0 0 0 -0.5 -0.5 -0.5 -0.5 -1 -1 -1 -1 -1 -1.0 -1.0 -1.0 -1.0 -1.0 Z [1000 AU] Z [1000 AU] Z [1000 AU] Z [1000 AU] Z [1000 AU] -2 -2 -2 -2 -2 -1.5 -1.5 -3 -3 -1.5 -3 -1.5 -3 -1.5 -3 -4 -4 -4 -4 -4 -2.0 -2 α-1 0 1 o 2 -2 α-1 0 1 o 2 -2 α-1 0 1 o 2 -2 α-1 0 1 o 2 -2 α-1 0 1 o 2 H R [1000 AU] 30 H R [1000 AU] 60 H R [1000 AU] 90 H R [1000 AU] 120 H R [1000 AU] 150 -0.5 -0.5 -0.5 1 1 1 1 1 -1.0 -1.0 -1.0 -1.0 -1.0 0 0 0 0 0 -1.5 -1.5 -1.5 -1.5 -1 -1 -1.5 -1 -1 -1 -2.0 -2.0 Z [1000 AU] Z [1000 AU] Z [1000 AU] Z [1000 AU] Z [1000 AU] -2 -2 -2.0 -2 -2.0 -2 -2.0 -2

-3 -2.5 -3 -3 -3 -3 -2.5 -2.5 -2.5 -2.5 -4 -4 -4 -4 -4

-2 -1 0 1 o 2 -2 -1 0 1 o 2 -2 -1 0 1 o 2 -2 -1 0 1 o 2 -2 -1 0 1 o 2 [NII]R 6584 [1000 AU] 30 [NII]R 6584 [1000 AU] 60 [NII]R 6584 [1000 AU] 90 [NII]R 6584 [1000 AU] 120 [NII]R 6584 [1000 AU] 150

-1.0 -1.0 -1.0 1 1 -1.0 1 1 -1.0 1 -1.5 -1.5 0 0 Richling-1.5 0 & Yorke (2000)-1.5 0 -1.5 0

-1 -2.0 -1 -1 -1 -1 -2.0 -2.0 -2.0 -2.0 Z [1000 AU] Z [1000 AU] Z [1000 AU] Z [1000 AU] Z [1000 AU] -2 -2.5 -2 -2 -2 -2 -2.5 -2.5 -2.5 -2.5 -3 -3 -3 -3 -3 -3.0 -3.0 -3.0 -3.0 -3.0 -4 -4 -4 -4 -4

-2 -1 0 1 o 2 -2 -1 0 1 o 2 -2 -1 0 1 o 2 -2 -1 0 1 o 2 -2 -1 0 1 o 2 [OI] R63 [1000 AU] 30 [OI] R63 [1000 AU] 60 [OI] R63 [1000 AU] 90 [OI] R63 [1000 AU] 120 [OI] R63 [1000 AU] 150 -0.2 0.0 -0.2 -0.2 -0.2 1 1 1 1 1 -0.4 -0.4 -0.2 -0.4 0 -0.4 0 0 0 0 -0.6 -0.4 -1 -0.6 -1 -0.6 -1 -1 -0.6 -1 -0.8 -0.6 Z [1000 AU] Z [1000 AU] Z [1000 AU] Z [1000 AU] Z [1000 AU] -2 -0.8 -2 -0.8 -2 -2 -0.8 -2 -1.0 -3 -3 -3 -0.8 -3 -3 -1.0 -1.0 -1.0 -4 -4 -4 -4 -4 -1.2

-2 -1 0 1 o 2 -2 -1 0 1 o 2 -2 -1 0 1 o 2 -2 -1 0 1 o 2 -2 -1 0 1 o 2 [CII]R 158 [1000 AU] 30 [CII]R 158 [1000 AU] 60 [CII]R 158 [1000 AU] 90 [CII]R 158 [1000 AU] 120 [CII]R 158 [1000 AU] 150 -1.2 -1.2 -1.2 1 1 1 1 1 -1.4 -1.8 -1.4 -1.4 0 -1.4 0 0 0 0 -1.6 -2.0 -1.6 -1.6 -1 -1.6 -1 -1 -1 -1 -1.8 -2.2 -1.8 -1.8 Z [1000 AU] Z [1000 AU] Z [1000 AU] Z [1000 AU] Z [1000 AU] -2 -1.8 -2 -2 -2 -2 -2.4 -2.0 -2.0 -3 -3 -3 -3 -3 -2.0 -2.0 -2.6 -4 -4 -2.2 -4 -4 -2.2 -4 -2.2 -2 -1 0 1 2 -2 -1 0 1 2 -2 -1 0 1 2 -2 -1 0 1 2 -2 -1 0 1 2 R [1000 AU] R [1000 AU] R [1000 AU] R [1000 AU] R [1000 AU]

3302 51000 3302 51000 3302 51000 3302 51000 3302 51000 [OII] 3726 30o [OII] 3726 60o [OII] 3726 90o [OII] 3726 120 o [OII] 3726 150 o

-0.5 1 -0.5 1 -0.5 1 -0.5 1 -0.5 1

0 0 0 0 0 -1.0 -1.0 -1.0 -1.0 -1.0 -1 -1 -1 -1 -1 -1.5 -1.5 -1.5 -1.5 -1.5 Z [1000 AU] Z [1000 AU] Z [1000 AU] Z [1000 AU] Z [1000 AU] -2 -2 -2 -2 -2 -2.0 -2.0 -2.0 -2.0 -2.0 -3 -3 -3 -3 -3

-4 -2.5 -4 -2.5 -4 -2.5 -4 -2.5 -4 -2.5

0 -0.5 0 0 0 0 -0.5 -0.5 -0.5 -0.5 -1 -1 -1 -1 -1 -1.0 -1.0 -1.0 -1.0 -1.0 Z [1000 AU] Z [1000 AU] Z [1000 AU] Z [1000 AU] Z [1000 AU] -2 -2 -2 -2 -2 -1.5 -1.5 -3 -3 -1.5 -3 -1.5 -3 -1.5 -3 -4 -4 -4 -4 -4 -2.0 -2 α-1 0 1 o 2 -2 α-1 0 1 o 2 -2 α-1 0 1 o 2 -2 α-1 0 1 o 2 -2 α-1 0 1 o 2 H R [1000 AU] 30 H R [1000 AU] 60 H R [1000 AU] 90 H R [1000 AU] 120 H R [1000 AU] 150 -0.5 -0.5 -0.5 1 1 1 1 1 -1.0 -1.0 -1.0 -1.0 -1.0 0 0 0 0 0 Comparison-1.5 with observations – Emission lines -1.5 -1.5 -1.5 -1 -1 -1.5 -1 -1 -1 -2.0 -2.0 Z [1000 AU] Z [1000 AU] Z [1000 AU] Z [1000 AU] Z [1000 AU] -2 -2 -2.0 -2 -2.0 -2 -2.0 -2

-3 -2.5 -3 -3 -3 -3 -2.5 -2.5 -2.5 -2.5 -4 -4 -4 -4 -4

-2 -1 0 1 o 2 -2 -1 0 1 o 2 -2 -1 0 1 o 2 -2 -1 0 1 o 2 -2 -1 0 1 o 2 [NII]R 6584 [1000 AU] 30 [NII]R 6584 [1000 AU] 60 [NII]R 6584 [1000 AU] 90 [NII]R 6584 [1000 AU] 120 [NII]R 6584 [1000 AU] 150

-1.0 -1.0 -1.0 1 1 -1.0 1 1 -1.0 1 -1.5 -1.5 0 0 -1.5 0 -1.5 0 -1.5 0

-1 -2.0 -1 -1 -1 -1 -2.0 -2.0 -2.0 -2.0 Z [1000 AU] Z [1000 AU] Z [1000 AU] Z [1000 AU] Z [1000 AU] -2 -2.5 -2 -2 -2 -2 -2.5 -2.5 -2.5 -2.5 -3 -3 -3 -3 -3 -3.0 -3.0 -3.0 -3.0 -3.0 -4 -4 -4 -4 -4

Richling & Yorke (2000)

3302 51000 3302 51000 3302 51000 3302 51000 3302 51000

Inﬂuence of stellar winds

Time [yr] 65595 v [km s-1 ] 100 Time [yr] 62013 v [km s-1 ] 200 norm norm 1000 1000 -22

-20 500 500 -20

-18 ] ] 0 -3 0 -3 -18 [g cm [g cm ρ ρ Z [AU] Z [AU]

-500 -16 log -500 log -16

-1000 -1000 -14 -14

-1500 -1500 -1000 -500 0 500 1000 -1000 -500 0 500 1000 R [AU] R [AU] Hα 60o Hα 60o

Sequence 3306 0.0 Sequence 3307 0.0 1 Model 83500 1 Model 68500 M /M 0.58 M /M 0.58 star sun -0.5 star sun -0.5 0 Mdisk/Msun 0.08 0 Mdisk/Msun 0.09

-1 -1.0 -1 -1.0

Z [1000 AU] -2 -1.5 Z [1000 AU] -2 -1.5

-3 -3 -2.0 -2.0 -4 -4 -2 -1 0 1 2 -2 -1 0 1 2 R [1000 AU] R [1000 AU] [OI] 63 60o [OI] 63 60o 0.0 1 -0.2 1 -0.2 0 0 -0.4 -0.4 -1 -1 -0.6 -0.6

Z [1000 AU] -2 Z [1000 AU] -2 -0.8 -3 -3 -0.8 -1.0 -4 -4 -2 -1 0 1 2 -2 -1 0 1 2 R [1000 AU] R [1000 AU]

33073306 6850083500 Inﬂuence of stellar winds – Micro-jets

[OIII] 5007 A˚ H [OI] 6300A˚ [OIII] 5007 60o Hα 60o [OI] 63 60o

1 1 0.5 1 -0.5 -0.4

-0.6 0 0 0.0 0 -1.0 -0.8 -0.5 -1.5 -1 -1 -1 Z [1000 AU] Z [1000 AU] Z [1000 AU] -1.0 -1.0 -2.0

[OIII] 5007 A˚ H [OI] 63 m -2 -2 -2 ¡ -1.2 -2.5 -1.5 -1 0 1 -1 0 1 -1 0 1 R [1000 AU] R [1000 AU] R [1000 AU]

3306 83500 Distance from ionizing source

Orion Nebula 49 −1 UV photon rate: ΦUV = 1.5x10 s

0.015 pc

14 12 5 arcsec = 0.01 pc 10 0.065 pc 8 6 4 number of proplyds 2 0 0 20 40 60 80 100 projected distance [arcsec] Distance from ionizing source

EUV-dominated ﬂow FUV-dominated ﬂow

-1 -1 Time [yr] 18506 vnorm [km s ] 50 Time [yr] 28336 vnorm [km s ] 50 -20 -20 400 400

200 -18 200 -18 ] ] 0 -3 0 -3

-16 [g cm -16 [g cm ρ ρ Z [AU] Z [AU] log log -200 -200

-14 -14

-400 -400

-12 -12 -400 -200 0 200 400 -400 -200 0 200 400 R [AU] R [AU]

./ps_grid3/3823.20000.ps ./ps_grid3/3821.26000.ps Photoevaporation rate

10-5 high UV ﬂux ¤ 1.5 ] 1 £ ˙

-1 EUV dominated: M ∝ r yr

yr ¢ sun

M ¡

ph -6 low UV ﬂux 1.25 10 ˙

M → Simulations: M ∝ r Mdot [M

FUV dominated: M˙ ∝ r1.0

10-7 100 1000 RC [AU]

„ «−0.75 „ «1.25 −6 −1 d rd M˙ = 1.6 × 10 M yr 1017 cm 100 AU

for log ΦEUV = 48.89 and log ΦFUV = 49.25 −7 −6 −1 → M˙ = 10 – 10 M yr for Orion proplyds Time-dependent photoevaporation

10000

Zhead-Ztail 1.00

1000

¢ ¡ ]

size/radius [AU] sun

disk low UV ﬂux R [M 0.10

H M disk low UV ﬂux M high UV ﬂux

100 high UV ﬂux RC

0.01 0 2 4 6 8 10 12 0 2 4 6 8 10 12 4 t [10 yr] t [104 yr]

→ Radius decreases with time M(t) = M0(t) × exp(−t/τ) 5 → Photoevaporation from“outside in” τ1/10 ∼ 10 yr → Photoevaporation time scale increases in agreement with semi-analytical calculations Photoevaporation and viscous accretion

Angular momentum transfer “α–prescription”(Shakura & Sunyaev 1973) Redistribution of angular momentum: viscosity coeﬃcient: ν ∝ αHcs • Inner material moves closer to the star (H: scale height, c: sound speed) " ! # • Outer material spreads out 1 ∂vj ∂vi 1 ∂vi Tij = ν + − δij 2 ∂xi ∂xj 3 ∂xi circumstellar disk 1.0 decrease of

photoevaporation time scale ¢ Photoevaporation and accretion ¡ ]

• Disk radius decreases more slowly sun −6

disk α = 10 [M M disk M 10000 α = 10−2

Zhead-Ztail

1000 0.1 0 1 2 3 4 RH t [104 yr]

Size/Radius [AU] 100 RC 1D study (Matsuyama et al. 2003) Photoevaporation and accretion destroy entire disk 10 6 7 0 1 2 3 external FUV radiation: 10 − 10 yr t [104 yr] external EUV radiation: 105 − 106 yr Photoevaporation from the central star

EUV radiation (> 13.6 eV) circumstellar disk massive star

FUV radiation (6 − 13.6 eV) Photoevaporation from the central star

EUV radiation: FUV radiation:

Time [yr] 83751 v [km s-1] 10 norm 3000 -20 2000 -19

1000

-18 ] -3

0 -17 [g cm ρ Z [AU] log -1000 -16

-15 -2000

-14 (Richling & Yorke 1997) -3000 -3000 -2000 -1000 0 1000 2000 3000 R [AU] Important for massive stars (> 8 M ) Sequence 2407 → formation of UCHII regions Model 36000 New Simulation:Mstar/Msun 1.14 Mdisk/Msun 0.74 „ «0.5 „ «0.5 −10 −1 ΦEUV M? 2.5 M , log ΦEUV=44.68, log ΦFUV=45.17 M˙ = 4×10 M yr 1041 s−1 M −6 −1 → M˙ = 5.4 × 10 M yr (Hollenbach et al. 1994) Important for low-mass stars? Other disk dispersal mechanisms

• viscous accretion onto the central source „ «−1 „ « 5 α r τacc = 10 yr 0.01 10 AU

• internal photoevaporation

„ Φ «−1/2 „ Σ « τ = 107 yr EUV 0 ph 41 −1 10 s Σmin

• close stellar encounters (dense clusters)

„ «−1 „ «−1 „ «−2 7 n? v r τse = 2 × 10 yr 104 pc−3 1 km s−1 100 AU

• stellar winds (early evolutionary phases)

1/4 2 !−1 −1 !−1 „ r « (sin θ) „ M «„ v « M˙ w τ = 107 yr d sw −4 −1 −8 −1 1 AU 10 Mmin 100 km s 10 M yr

(Hollenbach et al. 2000) Comparison of disk dispersal time scales

Trapezium conditions, Md = 0.01 M , radial orbits

109

108 viscous accretion intern 107 photoevaporation 106

Time [yr] stellar wind

105 stellar encounters 10-3 10-2 extern 104 10-2 10-1 100 101 102 103 104 105 Radius [AU] Implications for the formation of the solar system

R < ∼ 10 AU: viscous accretion R > ∼10 AU: photoevaporation

? Jupiter, Saturn Uranus, Neptune GM Rock-ice cores: 15 ME Rg = Rock-ice cores: 15 ME cs H/He envelope: ∼300, 75 ME H/He envelope: ∼ 2 ME

? ?

Planet formation via core accretion? Rapid planet formation?

Boss (2003): timescale τ = 104 yr gravitaionally bound clumps evolve in a marginally graviationally unstable disk