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Stellar Population Synthesis Including Planetary Nebulae

Stellar Population Synthesis Including Planetary Nebulae. Paola Marigo Astronomy Department, Padova University, Italy L èo Girardi Trieste Observatory, INAF, Italy. Why population synthesis of PNe?. Understand basic properties of PNe and their nuclei

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Stellar Population Synthesis Including Planetary Nebulae

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  1. Stellar Population SynthesisIncluding Planetary Nebulae Paola Marigo Astronomy Department, Padova University, Italy Lèo Girardi Trieste Observatory, INAF, Italy

  2. Why population synthesis of PNe? • Understand basic properties of PNe and their nuclei e.g. M-R relation, line ratios, optical thickness/thinness, transition time, nuclear regime (H-burn. or He-burn.) • Analyse PNLFs in different galaxies e.g. depedence of the bright cut-off on SFR, IMF, Z(t) • Constrain progenitors’ AGB evolution e.g. superwind phase, Mi-Mf relation, nucleosynthesis and dredge-up

  3. Basic requirements: extended grids of PN models • Simplified approach still necessary. Various degrees of approximation: AGB evolution, nebular dynamics; photoionisation • Kahn (1983,1989) • Kahn & West (1985) • Volk & Kwok (1985) • Stasińska (1989) • Ciardullo et al. (1989) • Jacoby (1989) • Kahn & Breitschwerdt (1990) • Dopita et al. (1992) • Mendez et al. (1993) • Stanghellini (1995) • Mendez & Soffner (1997) • Stasińska et al. (1998) • Stanghellini & Renzini (2000) • Marigo et al. (2001; 2004) • Recent improvements of hydrodynamical calculations: large sets now becoming available • Perinotto et al. 2004 • Schoenberner et al. 2005

  4. Synthetic PN evolution:basic ingredients • central star mass (Mi, Z) [p] • AGB wind • density and chemical comp. of the ejecta (r, t) • AGB EVOLUTION POST-AGB EVOLUTION • logL-logTeff tracks (H-burn./He burn.)[p] • fast wind DYNAMICAL EVOLUTION OF THE NEBULA • (Mneb, Vexp) parametrisation • .interacting-winds model[p] IONISATION AND NEBULAR EMISSION LINES • photoionisation code [p]or other semi-empirical recipe [p]

  5. Output of a synthetic PN model Mi=1.7 M; MCS= 0.6 M; Z=0.019 • Time evolution of: • Ionised mass • nebular radius • expansion velocity • optical configurations • emission line luminosities

  6. Synthetic Samples of PNe MONTE CARLO TECHNIQUE SCHEME A)(Jacoby, Mendez, Stasinska, Stanghellini) • Randomly generate a synthetic PN sample obeying a given central-star mass N(Mc) distribution •  Mi an age is randomly assigned in the [0, tPN] interval • Stellar and nebular parameters (L, Teff, Vexp, Mion, Rion, F) from grid-interpolations

  7. Synthetic Samples of PNe N(Mi,Z)  (Mi) (t– H) tPN MONTE CARLO TECHNIQUE SCHEME B)(Marigo et al. 2004) • Randomly generate a synthetic PN sample obeying a given initial mass N(Mi,Z) distribution •  Mi an age is randomly assigned in the [0, tPN] interval • Stellar and nebular parameters (L, Teff, Vexp, Mion, Rion, F) from grid-interpolations • H(Mi,Z)Main Sequence lifetime • tPN PN lifetime«H • (Mi) Initial mass function • (t– H) Star formation rate • Z(t) Age-metallicity relation N(Mi) Mi

  8. Different synthetic schemes Author Jacoby 89Stasinska91Mendez97 Stanghellini00 Marigo04 ———————————————————————————————————————————————— CS masses gaussian gaussian exponential+cut-off pop-synthesispop-synthesis PAGB tracks S83+WF86S83S83+B95 VW94 VW94 Dynamics (Mneb,Vneb)(Mneb,Vneb)interacting winds Line fluxes phot. modelphot. modelanalytic recipe phot. model SFR constant +cut-off constant various choices

  9. Properties of PNe and their Central Stars Mion-Rion relation Nel-Rion relation Line ratios Optical thickness/thinness Transition time Nuclear burning regime

  10. How to explain the observed invariance of the bright cut-off ? • Jacoby (1996):narrow CSPN mass distribution (0.58 ± 0.02 M) • over the age range (3-10 Gyr) , • i.e. initial mass range (1-2 M) • Ciardullo & Jacoby (1999) :circumstellar extinction • always estinguishes the overluminous • and massive-progenitor PNe • below the cut-off. • Marigo et al. (2004):still open problem, difficult to recover for • Ellipticals • IV. Ciardullo (2005): Possible contribution of PNe in binary systems • SO FAR NOT ROBUST THEORETICAL EXPLANATION

  11. WHICH PNe FORM THE CUT-OFF? 1. OIII5007 LUMINOSITIES AS A FUNCTION OF AGE Jacoby 1989 Stasińska et al. 1998 Marigo et al. 2004

  12. WHICH PNe FORM THE CUT-OFF? 2. CENTRAL MASS DISTRIBUTION AS A FUNCTION OF LIMITING MAGNITUDE MCSPN  0.70-0.75 M; Mi 2-3 M; age  0.5-1.0 Gyr Marigo et al. 2004

  13. DEPENDENCE ON THE AGE OF THE LAST EPISODE OF STAR FORMATION Jacoby 1989 Stanghellini 1995 0.77 0.695 0.68 Mendez & Soffner 1997 Marigo et al. 2004 Mmax=0.63 Mmax=0.70 Mmax=1.19 1.15 0.74 0.68 0.65 0.61

  14. A FEW CONCLUDING REMARKS • Population synthesis including PNe is a powerful • — still not fully exploited — tool to get insight into • several aspects of PNe and their central stars • e.g. ionised mass-radius rel.; electron density-radius rel.; • [OIII]5007/HeII4686 anticorrel., Te distribution; • [OIII]5007/H distribution; optical thickness/thinness; • H-/He-burners, transition time; Mi-Mf relation; distribution of • chemical abundances • Population-age dependence of the PNLF: • difficulty to explain the observed invariance of the bright • cut-off in galaxies from late to early types • Still to be included: full hydrodynamics, non-sphericity, • binary progenitors, etc.

  15. TRANSITION TIME MOSTLY UNKNOWN PARAMETER: dependence on Menv, pulse phase, MLR, Mcs, etc. Stanghellini & Renzini 2000

  16. (continued) DEPENDENCE OF THE PNLF ON TRANSITION TIME Stanghellini 1995 Marigo et al. 2004 Solid line: constat ttr; dashed line: mass -dependent ttr Differences in the bright cut-off due to different ttr show up for larger Mmax, or equivalently for younger ages

  17. DEPENDENCE OF THE PNLF ON H-/He-BURNING TRACKS Jacoby 1989 Marigo et al. 2004 H-burn. He-burn. Differences in the bright cut-off due to different tracks show up for older ages The bright cut-off is reproduced by more massive H-burning CS (0.65 M) compared to He-burning CS (0.61 M)

  18. Synthetic AGB evolution: observational constraints C-star LF Mi-Mf relation WD mass distr. Renzini & Voli 1981 Marigo 1999 Van der Hoek & Groenewegen 1997 Marigo 2001

  19. Post-AGB evolutionary tracks Mostly used sets: Schoenberner (1983) + Bloecker (1995) CS masses: 0.53 – 0.94 M Metallicities: Z=0.021 Vassiliadis & Wood (1994) CS masses: 0.59 – 0.94 M Metallicities: Z= 0.016, 0.008, 0.004, 0.001 Recent sets (synthetic): Frankovsky (2003) CS masses : 0.56 – 0.94 M Metallicities: Z= 0.016, 0.004 H-burning central stars He-burning central stars  loops  less luminous  longer evolutionary timescales

  20. PN DYNAMICS Simple scheme Combination of constant parameters (Mneb, Vexp, R/R) Interacting-winds model (Kahn 1983; Volk & Kwok 1985; Breitschwerdt & Kahn 1990)

  21. NEBULAR FLUXES: photoionisation codes Jacoby, Ciardullo et al. Stasinska et al. Marigo et al. INPUT •Nebular geometry • Rin, Rout • density N(H) •Elemental abundances (H,He,C,N,O,etc.) • L and Teff of the CSPN OUTPUT •Te (volume average) • ionisation fractions • line fluxes Example: CLOUDY (Ferland 2001) Mi=2.0 M; MCSPN=0.685 M; Z=0.008; H-burn.; Mion=0.091 M; tPN=3000 yr

  22. OPTICAL PROPERTIES OF THE NEBULA  ABSORBED IONISING PHOTONS ABSORBING FACTOR   (MKCJ93)  EMITTED IONISING PHOTONS • Mendez et al. :  randomly assigned as a function of Teff, following • results of model atmospheres applied to Galactic CSPN. • In particular, on heating tracks with T>40000 K a • random uniform distribution 0.05    max • Jacoby et al. Stasinska et al.derives from the coupling between nebular dynamics and photoionisation Marigo et al. Simulated PN sample: M5007<1; Ntot = 500 SFR=const.; Z=0.019; ttr=500 yr H-burn. and He-burn. tracks  optically thick ;  optically thin

  23. Ionised mass-radius relation Simulated PN sample: M5007<1; Ntot = 500 SFR=const.; Z=0.019; ttr=500 yr H-burn. and He-burn. tracks  optically thick ;  optically thin Observed data from Zhang (1995), Boffi & Stanghellini (1994)

  24. Electron density-radius relation Simulated PN sample: M5007<1; Ntot = 500 SFR=const.; Z=0.019; ttr=500 yr H-burn. and He-burn. tracks  optically thick ;  optically thin Observed data from Phillips (1998)

  25. Line ratios Stasinska 1989

  26. NEBULAR FLUXES: a semi-empirical recipe • Mendez et al. : Once specified(L,Teff) of the CSPN Recombination theory for optically thick case  H fluxes Random -factor correction  true H fluxes Empirical distributionI(5007)I(H)  HOIII5007 fluxes

  27. I([OIII]5007)/I(H) DISTRIBUTION of GALACTIC PNe Observed (McKenna et al. 1996) Predicted (He-burning tracks) Predicted (He-burning tracks)

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