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Hydrodynamical Interpretation of Basic Nebular Structures
M. Steffen & D. Schönberner Astrophysikalisches Institut Potsdam, Germany Abell 39 (WIYN)
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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%)
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Observed PN structures: An overview
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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 K Teff K Sharp ionization front, optically thick in Ly-continuum
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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 K Halo Teff K Typical double-shell PNe, optically thin in Ly-continuum
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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 2x /10/ TOTAL 1 hour Einstein Cross V600 blue 4x /10/ TOTAL 2 hours OIII, short NGC 6826, observed with PMAS A&G camera (© 2004, M. Roth)
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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 K Teff K Halo Typical double-shell PNe, optically thin in Ly-continuum
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NGC 2022 [OIII] images obtained with NTT/EMMI (Corradi et al. 2003)
Example of an AGB halo: NGC 2022 Einstein Cross V600 blue 2x /10/ TOTAL 1 hour Einstein Cross V600 blue 4x /10/ TOTAL 2 hours NGC 2022 [OIII] images obtained with NTT/EMMI (Corradi et al. 2003)
![NGC 2022 [OIII] images obtained with NTT/EMMI (Corradi et al. 2003)](http://slideplayer.com./slide/9205555/27/images/8/NGC+2022+%5BOIII%5D+images+obtained+with+NTT%2FEMMI+%28Corradi+et+al.+2003%29.jpg "Example of an AGB halo: NGC Einstein Cross V600 blue 2x /10/01 TOTAL 1 hour Einstein Cross V600 blue 4x /10/01 TOTAL 2 hours. NGC 2022 [OIII] images obtained with NTT/EMMI (Corradi et al. 2003)")
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Single-shell PN, fully ionized
Examples of old Planetary Nebulae Abell 39 WIYN [OIII] image NGC 3587 KPNO 0.9m Rim no Shell Teff K Teff K Double-shell PN, but no bright rim partially ionized, complex morphology Single-shell PN, fully ionized
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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 K L 500 L (Data from Corradi et al. 2000) Triple-shell configuration, partially recombined 2nd shell ?
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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
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Origin and evolution of
observed structures ? Theoretical concepts and models including the essential physics !
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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
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Rotation, magnetic fields, binarity ?
Example of complex structures: NGC 6543 HST color composite Einstein Cross V600 blue 2x /10/ TOTAL 1 hour Einstein Cross V600 blue 4x /10/ TOTAL 2 hours Rotation, magnetic fields, binarity ?
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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
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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)
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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 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) cm ISM
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The final 350 000 years on the AGB
Stellar evolution + two-component hydrodynamics: Stellar evolution: Blöcker 1995 ( Mi = 3 M Mf = M ) Dust: astronomical silicates (r) ~ r-, 3 V(r) km/s Steffen et al / 2005
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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) 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-t1200 yrs double-peak SED in PPN phase
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The first 3 000 years of post-AGB evolution
M=0.595 M
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Snapshot: IC 418 M=0.595 M
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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
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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)
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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 K fast wind 2: colliding winds fast central star wind shock hot bubble compression of shell rim inner wind shock Slow AGB wind
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The formation of a double-shell nebula
M=0.595 M
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Snapshot: NGC 6826 M=0.595 M Rim Shell Shell Rim Halo Halo
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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
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Observed and synthetic surface brightness distributions
NGC 6826 H NGC 3242 H NGC 1535 H
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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]
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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 (Data © 1999 Lehmann/Hildebrandt) Model nebula (Teff= 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
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Observed expansion velocities of double-shell PNe
(Schönberner et al. 2005) Doppler velocities from Gaussian decomposition Vshell > Vrim Expansion velocities increase with evolution
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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
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The phase of partial recombination
M=0.605 M
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Snapshot: NGC 2438 M=0.605 M Rim Shell Shell Rim
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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:
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PN evolution of low mass CS: no recombination phase
M=0.565 M
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Snapshot: Abell 39 M=0.565 M
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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
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PN evolution of massive CS: trapped ionization
M=0.696 M
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Snapshot: NGC 7027 M=0.696 M rim shell
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Comparison of observation and model: NGC 7027
Surface brightness profiles: HST NICMOS IR image rim shell Teff K, L 8000 L Optically thick rim/shell structure Diffuse outer edge of shell: D-type ionization front beginning recombination Schönberner, Jacob, Steffen 2005
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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
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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
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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-
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The halo of NGC 6826 Inner halo: I ~ r –, 5 .. 7
Outer edge: last TP on AGB ~ r –, (Corradi et al. 2003)
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Structure and expansion properties of
Planetary Nebulae provide constraints on the final phases of AGB mass loss AGB ~ r –, 2.5 < < 3.5 AGB: > (Kwok et al. 2002) PPN: 3 < < 4 (Hrivnak & Bieging 2005) Mass loss increases towards end of AGB
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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)
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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
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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
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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
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