Hydrodynamical Interpretation of Basic Nebular Structures M. Steffen & D. Schönberner Astrophysikalisches Institut Potsdam, Germany Abell 39 (WIYN)

Hydrodynamical Interpretation of Basic Nebular Structures M. Steffen & D. Schönberner Astrophysikalisches Institut Potsdam, Germany Introduction: observed structures PN physics and hydrodynamical modeling  Results from state-of-the-art simulations  typical time evolution of PN structures  dependence on mass loss of AGB progenitor Conclusions and outlook Manchado 2003: Round: 25% (22%), Elliptical 58% (66%), Bipolar 17% (12%)

Observed PN structures: An overview

Sharp ionization front, optically thick in Ly-continuum Examples of young Planetary Nebulae He 2-131 HST H Image IC 418 HST H Image Teff  30 000 K Teff  36 000 K Sharp ionization front, optically thick in Ly-continuum

Typical double-shell PNe, optically thin in Ly-continuum Examples of middle-aged Planetary Nebulae NGC 6826 HST color composite IC 3568 HST V image Rim Shell Teff  50 000 K Halo Teff  50 000 K Typical double-shell PNe, optically thin in Ly-continuum

NGC 6826, observed with PMAS A&G camera (© 2004, M. Roth) Example of an AGB halo: NGC 6826 AGB Halo OIII, long Einstein Cross V600 blue 2x1800 23/10/01 TOTAL 1 hour Einstein Cross V600 blue 4x1800 25/10/01 TOTAL 2 hours OIII, short NGC 6826, observed with PMAS A&G camera (© 2004, M. Roth)

Typical double-shell PNe, optically thin in Ly-continuum Examples of middle-aged Planetary Nebulae NGC 3242 HST V image NGC 2022 HST V image Rim Shell Xrays Teff  75 000 K Teff  100 000 K Halo Typical double-shell PNe, optically thin in Ly-continuum

NGC 2022 [OIII] images obtained with NTT/EMMI (Corradi et al. 2003) Example of an AGB halo: NGC 2022 Einstein Cross V600 blue 2x1800 23/10/01 TOTAL 1 hour Einstein Cross V600 blue 4x1800 25/10/01 TOTAL 2 hours NGC 2022 [OIII] images obtained with NTT/EMMI (Corradi et al. 2003)

Single-shell PN, fully ionized Examples of old Planetary Nebulae Abell 39 WIYN [OIII] image NGC 3587 KPNO 0.9m Rim no Shell Teff  110 000 K Teff  117 000 K Double-shell PN, but no bright rim partially ionized, complex morphology Single-shell PN, fully ionized

Example of an old Planetary Nebulae NGC 2438 NTT H+[NII] NGC 2438 NTT H+[NII] Bright halo Faint halo Bright ´core´ Bright ´core´ Teff  114 000 K L  500 L (Data from Corradi et al. 2000) Triple-shell configuration, partially recombined 2nd shell ?

X-ray detection of hot gas in PNe NGC 3242 Sharply bounded diffuse X-ray emission from central cavity Central Cavity Shell Rim central star (no X-ray source) Limb-brightening x-ray morphology Tight correlation morphology with H-alpha The wind-wind interaction works, we’ll see later some problems Point-source HST [N II] HST H XMM X-rays © M. Guerrero 2005

Origin and evolution of observed structures ? Theoretical concepts and models including the essential physics !

Hydrodynamical modeling of Planetary Nebulae Essential physical ingredients: AGB & post-AGB stellar evolution with mass loss Teff (t), L (t), M(t), Vwind (t) • Radiation hydrodynamics of stellar winds Dust-driven outflows (AGB) Wind -wind interaction (PPN, PN) Potsdam NEBEL Models Non-equilibrium physics of a low-density plasma time-dependent ionization / recombination  energy balance due to radiative heating / cooling 1D  Rotation, magnetic fields, binarity  2D, 3D

Rotation, magnetic fields, binarity ? Example of complex structures: NGC 6543 HST color composite Einstein Cross V600 blue 2x1800 23/10/01 TOTAL 1 hour Einstein Cross V600 blue 4x1800 25/10/01 TOTAL 2 hours Rotation, magnetic fields, binarity ?

Modeling the combined evolution of star + circumstellar envelope Hydrodynamical models of Planetary Nebulae Modeling the combined evolution of star + circumstellar envelope Post-AGB tracks of Blöcker (1995) Post-AGB mass loss rate and wind velocity (Reimers 1975; Pauldrach et al. 1988; Marten & Schönberner 1991) Initial wind envelope: from hydrodynamical AGB wind model (Steffen et al. 1998) [or simple density power law  ~ r-] Dynamical evolution of wind envelope:  time-dependent boundary conditions ( Teff (t), L (t), Vi (t), i (t) )  time-dependent hydrodynamics  non-equilibrium ionization / recombination (9 elements, 76 ions)  detailed radiative heating / cooling

Evolution of a PN central star with M=0.6 M Lwind Reimers (1975) Pauldrach et al. (1988, A&A 207, 123) VCPN Vesc  R-0.5 M  L 1.9 Pauldrach et al. (1988, A&A 207, 123)

AGB wind model gas & dust gas & dust Input: Mini, i  stellar evolution M*(t), L*(t), T*(t), M*(t) Dust properties Tc, a, I, Qabs(), Qsca() d/ g • Slow AGB wind V  10 .. 15 km/s gas & dust dust-free gas & dust zone Output: Wind structure & evolution r1(t), Vg(r,t), Vd(r,t), g(r,t), d(r,t), Td(r,t) Maps I(x,t,) SEDs F(,t) 5 1014 cm ISM

The final 350 000 years on the AGB Stellar evolution + two-component hydrodynamics: Stellar evolution: Blöcker 1995 ( Mi = 3 M  Mf = 0.605 M ) Dust: astronomical silicates (r) ~ r-,   3 V(r)  10 .. 15 km/s Steffen et al. 1998 / 2005

Environment for PN formation: detached gas/dust envelope with Transition AGB  post-AGB Environment for PN formation: detached gas/dust envelope with =-2 (r) ~ r-,   3 V(r)  10 .. 15 km/s =-3 Po =100 d Po = 50 d Reimers 1975 Blöcker (1995) mass loss rate AGB  post-AGB transition Pauldrach et al. 1988 Short shut-down time t2-t1200 yrs  double-peak SED in PPN phase

The first 3 000 years of post-AGB evolution M=0.595 M

Snapshot: IC 418 M=0.595 M

Comparison of observation and model: IC 418 Surface brightness profiles: IC 418 HST H Image d [arcsec] Proto rim Proto rim Sharp outer edge of shell: D-type ionization front Future rim very faint: wind interaction still weak

Observed and synthetic line profiles: IC 418 Central line profiles indicate positive velocity gradient: 2 x 15 km/s 2 x 15 km/s [N II] [N II] [O III] [O III] Observation © 2003 R. Corradi Model nebula (Teff=36300 K, optically thick)

Physical structure of a Planetary Nebula Slow AGB wind Shell 104 K outer shock Rim 104 K PN shaped by 1: photoionization by UV radiation of hot central star  shell Contact discontinuity hot Bubble 106 .. 108 K fast wind 2: colliding winds fast central star wind  shock  hot bubble  compression of shell  rim inner wind shock Slow AGB wind

The formation of a double-shell nebula M=0.595 M

Snapshot: NGC 6826 M=0.595 M Rim Shell Shell Rim Halo Halo

Observed and modeled surface brightness profiles (Schönberner, Jacob & Steffen, 2005) NGC 6826 – [O III] IC 2448 – [O III] NGC 3242 – [O III] NGC 3242 – He II

Observed and synthetic surface brightness distributions NGC 6826 H NGC 3242 H NGC 1535 H

Comparison of observation and model: NGC 3242 Stellar evolution + radiation hydrodynamics: CCD images (Balick 1987): H [O III] H [O III] [He II] [N II] [N II] [He II]

Observed and synthetic line profiles: NGC 6826 [O III] [O III] 2 x 8 km/s Rim 2 x 24 km/s Shell Chu et al. 1984 (Data © 1999 Lehmann/Hildebrandt) Model nebula (Teff=67 800 K) Rim and shell expand independently (different driving mechanisms)  Vrim ~ strength of central star wind & ambient density ( MAGB ) Vshell ~ density gradient of ambient AGB wind & sound speed

Observed expansion velocities of double-shell PNe (Schönberner et al. 2005) Doppler velocities from Gaussian decomposition Vshell > Vrim Expansion velocities increase with evolution

Expansion velocities and kinematic ages of double-shell Planetary Nebulae (Schönberner, Jacob & Steffen 2005) Rim Shell Kinematic age [1000 yr] Kinematic age [1000 yr] True age [1000 yr] True age [1000 yr] Rim Doppler velocity: roughly constant kinematic age  useless Shell Doppler velocity: kinematic age  real age  [N II] preferred method

The phase of partial recombination M=0.605 M

Snapshot: NGC 2438 M=0.605 M Rim Shell Shell Rim

Observation and model: NGC 2438 H+[N II] H+[N II] Outer halo = Fossil AGB wind Inner halo = Recombined shell Bright core = Rim NTT image, Corradi et al. 2000 Hydrodynamical interpretation:

PN evolution of low mass CS: no recombination phase M=0.565 M

Snapshot: Abell 39 M=0.565 M

Observation and model: Abell 39 Surface brightness profiles: relic of shell Observed E-W [O III] slice (Jacoby et al. 2001) Hydrodynamical model, M=0.565 M (Perinotto et al. 2004) Shell swallowed by rim

PN evolution of massive CS: trapped ionization M=0.696 M

Snapshot: NGC 7027 M=0.696 M rim shell

Comparison of observation and model: NGC 7027 Surface brightness profiles: HST NICMOS IR image rim shell Teff  200 000 K, L  8000 L Optically thick rim/shell structure Diffuse outer edge of shell: D-type ionization front  beginning recombination Schönberner, Jacob, Steffen 2005

Does the AGB mass loss history influence the PN evolution ? Yes ! Structure and expansion properties of Planetary Nebulae provide constraints on the final phases of AGB mass loss

Influence of AGB mass loss on PN structure AGB Hydro simulation (r) ~ r-,   3 H surface brightness Rim Shell Halo Simple initial model (r) ~ r-2 H surface brightness Rim Shell Halo

Circumstellar environment and expansion properties of Planetary Nebulae (Schönberner et al. 2005) Typical double-shell PNe: 25 km/s < Vshell < 40 km/s (Vshell-VAGB) / cs  2.5 <  < 3.3 Shell expansion velocity depends only on slope of AGB wind density  (and cs) (cf. Chevalier 1997, Shu et al. 2002) Initial AGB wind density:   r-

The halo of NGC 6826 Inner halo: I ~ r –,   5 .. 7 Outer edge: last TP on AGB   ~ r –,   3 .. 4 (Corradi et al. 2003)

Structure and expansion properties of Planetary Nebulae provide constraints on the final phases of AGB mass loss AGB ~ r –, 2.5 <  < 3.5 AGB:  > 2.5 (Kwok et al. 2002) PPN: 3 <  < 4 (Hrivnak & Bieging 2005) Mass loss increases towards end of AGB

How does the central star wind influence the PN evolution ? Comparison of two different wind models: Pauldrach et al. (1988) Pauldrach et al. (2004) Pauldrach et al. (1988) Pauldrach et al. (2004)

Influence of central star wind on rim structure CSPN wind: Pauldrach et al. (1988) CSPN wind: Pauldrach et al. (2004) Rim: density gradient & velocity gradient reversed, increased width

Conclusions Time-dependent 1D modeling combining  Single star evolution with mass loss +  radiation-hydrodynamics of stellar winds +  non-equilinrium low-density plasma physics can explain the observed basic nebular structures:  X-ray emission of the central hot bubble  radial intensity profiles in various emission lines  internal kinematics and expansion properties  structure and evolution of PN haloes Models allow a classification of observed PNe in terms of evolutionary state and central star mass

Discussion & Outlook Main uncertainties of present models: Mass loss during end of AGB and beyond Transition times Improved models:  New AGB and post-AGB tracks with mass loss PN evolution for different metallicities  PN evolution for Wolf-Rayet (WC) central stars