Planetary nebulae beyond the Milky Way - May 19-21, 2004

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Magellanic Cloud planetary nebulae as probes of stellar evolution and populations

Letizia Stanghellini

Planetary nebulae beyond the Milky Way - May 19-21, 2004 2

Magellanic Cloud PNe

The known distances, low field reddening, relative proximity, and metallicity range make them

Absolute probes of post-AGB evolution

Benchmarks for extragalactic PN populations

Planetary nebulae beyond the Milky Way - May 19-21, 2004 3

Probes of post-AGB evolution

• Nebular analysis• Morphology• chemistry

• Links to central stars (CSs)• Transition time• Winds

Planetary nebulae beyond the Milky Way - May 19-21, 2004 4

Benchmarks for extragalactic PN populations

• PNe and UCHII regions

• Luminosity distribution and metallicity

• PNe types in the PNLF

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PN morphology

· Depends on the formation and dynamic evolution of the PN, on the evolution of the central star and of the stellar progenitor, and on the environment.

· From Galactic PNe:· Round, Elliptical, Bipolar [includes bipolar core

and multipolar], and Point-symmetric· Bipolar PNe are located in the Galactic plane, have

high N, He, indication of massive CSs: remnant of 3-8 M stars?

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Round PNe (R) are a minority (22 % of all Galactic PNe with studied morphology)

49% elliptical (E)

17% bipolar (or multi-polar) (B)9% have an equatorial enhancement, or ring (lobe-less bipolar, or bipolar cores) (BC)

3% point-symmetric

Sym

metric | A

sym

metric

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HST and spatial resolution

LMC SMP 10HST STIS

-----3 arcsec -------

------------35 arcsec ----------------------

8

_48

61

H

_49

59

[O III]

_50

07

[O

III]

_63

00

[O

I] 658

4 [N

II]6

56

3 H

6

54

8 [N

II] 6

73

2 [S

II]6

71

6 [S

II]

Slitless Spectra of LMC SMP 16 G430M (4818—5104) and G750M (6295—6867)

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Round

Elliptical

Bipolar

Point-symmetric

Galaxy LMC SMCSym

metric | A

sym

metric

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Morphological distribution

LMC SMC

Round R 29 % 35 %

Elliptical E 17 % 29 %

R+E (symm.) 46 % 64 %

Bipolar B 34 % 6 %

Bipolar core BC

17 % 24 %

B+BC (asymm.)

51 % 30 %

Point-symmetric

3 % 6 %

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What is the physical origin of the equatorial disks?

• stellar rotation? Maybe associated with• a strong magnetic field? Garcia-Segura 97 (single magnetic WD are more massive than non-magnetic WDs! Wickramasinge & Ferrario 2000)• Binary evolution of the progenitor (CE)? Morris 81; Soker 98

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Chemistry

· PNe enrich the ISM · He, C, N, O abundances are linked to the evolution

of the progenitors· C-rich for massive progenitors (MZAMS < 3 Msun)· He- and N-rich (and C-poor) if MZAMS > 3 Msun

· Ar, S, Ne are invariant during the evolution of stars in this mass range they are signature of the protostellar ambient, thus test previous evolutionary history

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Primordial elements, LMC

O Round

* Elliptical

Bipolar core

Bipolar

LMC HII regions (average)

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Primordial elements, LMC

O Round

* Elliptical

Bipolar core

Bipolar

LMC HII regions (average)

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LMC PN morphology and the products of stellar evolution

O Round

* Elliptical

Bipolar core

Bipolar

LMC HII regions (average)

16

SMP16

SMP 95

SMP 34

Si IV N IV C IV] He II

Decre

asin

g e

xcita

tion cla

ss --->

17

SMP16

SMP 95

SMP 34

C III ] C II]

[Ne IV]

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Optical AND UV morphology

C III]1908 C II] 2327 [Ne IV] 2426 nebular

continuum LMC SMP 95

Broad band [O III] 5007 [N II] H [N

II]

Planetary nebulae beyond the Milky Way - May 19-21, 2004 19

UV spectra fitting

Planetary nebulae beyond the Milky Way - May 19-21, 2004 20

P-Cygni profiles

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Wind momentum vs. luminosity

See p

oste

r by A

. Arrie

ta

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Transition time

· Transition time (ttr) is measured from the envelope ejection quenching (EEQ) and the PN illumination; it is regulated by wind and/or nuclear evolution

· MeR (residual envelope mass at EEQ) determines ttr

dyn =DPN/vexp represent the dynamic PN age. If DPN is measured on main shell, dyn tracks time from EEQ

dyn =ttr+ tev (tev= time after PN illumination, corresponding to evolutionary time if tracks have zero point at illumination)

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Dealing with unsynchronized clocks

· ttr is an essential parameter in post-AGB population synthesis (e.g., PNLF high luminosity cutoff, and UV contribution from post-AGB stars in galaxies)

· Mass-loss at TP-AGB and beyond not completely understood, and Me

R now known· Only way to constraint ttr is observationally

· > Magellanic PNe offer the first direct estimates of transition time

· Assumptions: no acceleration of shells; He-tracks scaled to H-burning tracks

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dyn and tev

LMC

SMC

Round: symm. PNe (R,E)

Square: asymm. PNe (B,BC,P)

H-burning central stars

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Distribution of ttr in MC PNe

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MeR=1e-3 Me

R=2e-3

MeR=5e-3 Me

R=1e-2

Data

LMC PNe SMC Pne

Modelstwind

tnucl

ttr

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Total mass loss (IMFMR)Data: optically thin LMC and

SMC PNeHydro models:

solid line =PN shells broken line=outer halos

--> To constrain IMFMR we need to measure mass in PN halos (and in CSs)

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Importance of spatially-resolved PN populations

· We sampled ~50 (+30) LMC and ~30 SMC PNe, chosen among the brightest known (based on on H and [O III] 5007 fluxes )

· All LMC PN candidates are indeed PNe · ~10% of the SMC PN candidates are H II

regions

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MA 1796 MA 1797 MG 2

Log F C 1.53 ... 1.4

Size [arcsec] 3 11 3.5

Size [pc] 0.85 3.1 0.98

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Observed distributions of I(5007)/I(Hb)LMC

SMC

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Cloudy models

AGB

TP-AGB

Super-windtrans.PN + CS Nuclear reactions end

Cooling

WD

Teff

L

Galaxy

LMC

SMC

33SMC GalaxyLMC

PN cooling in different galaxies

Our HST data:

LMC

<I(5007)/I(H)>=9.4 (3.1)

<I(1909)/I(H)>=5 (5)

SMC

<I(5007)/I(H)>=5.7 (2.5)

UV: Cycle 13

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PNe in the PNLF

Open circles: R

Asterisks: E

Triangles: BC

Squares: B

Filled circles: P

O round; * elliptical; bipolar core; bipolar

LMC SMC

Fain

t---

----

--->

bri

gh

t

35

CSs in PNLF

LMC

SMC

Fain

t-----------> b

right

SMC HLCO

LMC HLCO

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Summary, and the future

• HST fundamental for shapes/ radii, but also for identification (misclassified H II regions in SMC but not in LMC metallicity effect?)

• Same morphology types in Galaxy, LMC, SMC, but more asymmetric PNe in LMC than SMC different stellar generations?

• Asymmetric LMC PNe have high Ne, S, Ar--> signature of younger progenitors

• Similar UV and optical morphology

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Summary, cont.

• Carbon higher for symmetric PNe, STIS UV spectra of LMC PNe to be analyzed; SMC PNe in Cycle 13

• P-Cygni profiles as signature of CS winds, distance indicator for galactic PNe

• Transition time constrained from observation enlarge sample, hydro+stellar modeling

• IMFM relation constraints• [O III]/Hflux ratio of a PN population variant

with host galaxy

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•Symmetric PNe populate the high luminosity parts of the PNLF•High mass CSs populate the faint end of the LF, sample to be extended

Summary, cont.

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