Magellanic Cloud planetary nebulae as probes of stellar evolution - - PowerPoint PPT Presentation

Planetary nebulae beyond the Milky Way - May 19-21, 2004 1

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

Planetary nebulae beyond the Milky Way - May 19-21, 2004 5

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?

6

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 Symmetric | Asymmetric

7

HST and spatial resolution

LMC SMP 10 HST STIS

• ----3 arcsec -------
• -----------35 arcsec ----------------------

8

_4861 Hβ _4959 [O III] _5007 [O III] _6300 [O I] 6584 [N II] 6563 Hα 6548 [N II] 6732 [S II] 6716 [S II] Slitless Spectra of LMC SMP 16

G430M (4818—5104) and G750M (6295—6867)

9

Round Elliptical Bipolar Point-symmetric

Galaxy LMC SMC

Symmetric | Asymmetric

10

Morphological distribution

64 % 46 % R+E (symm.) 30 % 51 % B+BC (asymm.) 6 % 3 % Point-symmetric 24 % 17 % Bipolar core BC 6 % 34 % Bipolar B 29 % 17 % Elliptical E 35 % 29 % Round R SMC LMC

11

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

Planetary nebulae beyond the Milky Way - May 19-21, 2004 12

Chemistry

· PNe enrich the ISM

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

• f 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

13

Primordial elements, LMC

O Round

*

Elliptical

Bipolar core

Bipolar ⊗ LMC HII regions (average)

14

Primordial elements, LMC

O Round

*

Elliptical

Bipolar core

• Bipolar

⊗ LMC HII regions (average)

15

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

Decreasing excitation class --->

17

SMP16 SMP 95 SMP 34

C III ] C II] [Ne IV]

18

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] Hα [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

21

Wind momentum vs. luminosity

See poster by A. Arrieta

22

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

• τdyn =DPN/vexp represent the dynamic PN age.

If DPN is measured on main shell, τdyn tracks time from EEQ

• τdyn =ttr+ tev (tev= time after PN illumination,

corresponding to evolutionary time if tracks have zero point at illumination)

Planetary nebulae beyond the Milky Way - May 19-21, 2004 23

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 MeR now known · Only way to constraint ttr is observationally · > Magellanic PNe offer the first direct estimates of transition time

24

τdyn and tev

LMC SMC Round: symm. PNe (R,E) Square: asymm. PNe (B,BC,P) H-burning central stars

25

Distribution of ttr in MC PNe

26

Me

R=1e-3

Me

R=2e-3

Me

R=5e-3

Me

R=1e-2

Data LMC PNe SMC Pne

Models twind tnucl ttr

27

Total mass loss (IMFMR)

Data:

• ptically thin LMC and

SMC PNe Hydro models: solid line =PN shells broken line=outer halos

• -> To constrain IMFMR we

need to measure mass in PN halos (and in CSs)

Planetary nebulae beyond the Milky Way - May 19-21, 2004 28

Importance of spatially- resolved PN populations

· We sampled ~50 (+30) LMC and ~30 SMC PNe, chosen among the brightest known (based

• n on Hβ and [O III] 5007 fluxes )

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

Planetary nebulae beyond the Milky Way - May 19-21, 2004 29

MA 1796 MA 1797 MG 2

Log Fβ −13.85 ... −14.3 C 1.53 ... 1.4 Size [arcsec] 3 11 3.5 Size [pc] 0.85 3.1 0.98

30

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

LMC SMC

31

Cloudy models

AGB TP-AGB Super-wind trans. PN + CS Nuclear reactions end Cooling WD Teff L

Galaxy LMC SMC

32

Cloudy models, varying density

SMC LMC Galaxy

33

SMC Galaxy LMC

PN cooling in different galaxies

Our HST data: LMC <I(5007)/I(Hβ)>=9.4 (3.1) <I(1909)/I(Hβ)>=5 (5) SMC <I(5007)/I(Hβ)>=5.7 (2.5) UV: Cycle 13

34

PNe in the PNLF

Open circles: R Asterisks: E Triangles: BC Squares: B Filled circles: P

O round; * elliptical; bipolar core; bipolar

LMC SMC

Faint----------> bright

35

CSs in PNLF

LMC SMC

Faint-----------> bright

SMC HLCO LMC HLCO

Planetary nebulae beyond the Milky Way - May 19-21, 2004 36

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

Planetary nebulae beyond the Milky Way - May 19-21, 2004 37

Summary, cont.

• Carbon higher for symmetric PNe, STIS UV spectra
• f 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]/Hβ flux ratio of a PN population variant with

host galaxy

Planetary nebulae beyond the Milky Way - May 19-21, 2004 38

• 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.

·