Stellar Population Synthesis Including Planetary Nebulae

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

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Basic requirements extended grids of PN models

• Kahn (1983,1989)
  
• Kahn West (1985)
• Volk Kwok (1985)
• Stasinska (1989)
• Ciardullo et al. (1989)
• Jacoby (1989)
• Kahn Breitschwerdt (1990)
• Dopita et al. (1992)
• Mendez et al. (1993)
• Stanghellini (1995)
• Mendez Soffner (1997)
• Stasinska et al. (1998)
• Stanghellini Renzini (2000)
• Marigo et al. (2001 2004)

• Simplified approach still necessary.
• Various degrees of approximation
• AGB evolution, nebular dynamics
• photoionisation

• Recent improvements of
• hydrodynamical calculations
• large sets now becoming available

• Perinotto et al. 2004
• Schoenberner et al. 2005

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Synthetic PN evolutionbasic 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

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Output of a synthetic PN model
Mi1.7 M? MCS 0.6 M? Z0.019

• Time evolution of
• Ionised mass
• nebular radius
• expansion velocity
• optical configurations
• emission line luminosities

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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

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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
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Different synthetic schemes
Author Jacoby 89 Stasinska91
Mendez97 Stanghellini00
Marigo04
CS masses gaussian
gaussian exponentialcut-off
pop-synthesis pop-synthesis PAGB tracks
S83WF86 S83 S83B95
VW94
VW94 Dynamics (Mneb,Vneb) (Mneb,Vneb)
?? ??
interacting winds Line fluxes phot.
model phot. model analytic recipe
?? phot. model SFR
?? ??
constant cut-off constant
various choices
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Properties of PNe and their Central Stars
Mion-Rion relation Nel-Rion relation Line
ratios Optical thickness/thinness Transition
time Nuclear burning regime
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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

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WHICH PNe FORM THE CUT-OFF?
1. ?OIII? ?5007 LUMINOSITIES AS A FUNCTION OF AGE
Jacoby 1989
Stasinska et al. 1998
Marigo et al. 2004
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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
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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
Mmax0.63 Mmax0.70 Mmax1.19
0.61
0.65
0.68
0.74
1.15
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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.

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TRANSITION TIME
MOSTLY UNKNOWN PARAMETER dependence on Menv,
pulse phase, MLR, Mcs, etc.
Stanghellini Renzini 2000
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(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
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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?)
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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
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Post-AGB evolutionary tracks
Mostly used sets Schoenberner (1983) Bloecker
(1995) CS masses 0.53 0.94 M? Metallicities
Z0.021 Vassiliadis Wood (1994) CS masses
0.59 0.94 M? Metallicities Z 0.016, 0.008,
0.004, 0.001 Recent sets (synthetic) Frankovsk
y (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
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PN DYNAMICS
Simple scheme
Combination of constant parameters (Mneb, Vexp,
?R/R)
Interacting-winds model
(Kahn 1983 Volk Kwok 1985 Breitschwerdt
Kahn 1990)
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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) Mi2.0 M?
MCSPN0.685 M? Z0.008 H-burn. Mion0.091 M?
tPN3000 yr
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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 Tgt40000 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 lt 1 Ntot
500 SFRconst. Z0.019 ttr500 yr H-burn. and
He-burn. tracks ? optically thick ? optically
thin
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Ionised mass-radius relation
Simulated PN sample M5007 lt 1 Ntot
500 SFRconst. Z0.019 ttr500 yr H-burn. and
He-burn. tracks ? optically thick ? optically
thin
Observed data from Zhang (1995), Boffi
Stanghellini (1994)
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Electron density-radius relation
Simulated PN sample M5007 lt 1 Ntot
500 SFRconst. Z0.019 ttr500 yr H-burn. and
He-burn. tracks ? optically thick ? optically
thin
Observed data from Phillips (1998)
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Line ratios
Stasinska 1989
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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
  distribution I(?5007)?I(H?) ? H?OIII? ?5007 fluxes

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I(OIII?5007)/I(H?) DISTRIBUTION of GALACTIC PNe
Observed (McKenna et al. 1996)
Predicted (He-burning tracks) Predicted
(He-burning tracks)