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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
Sym
metric | A
sym
metric
7
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)
9
Round
Elliptical
Bipolar
Point-symmetric
Galaxy LMC SMCSym
metric | A
sym
metric
10
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 %
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
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
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
Decre
asin
g e
xcita
tion cla
ss --->
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] 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
21
Wind momentum vs. luminosity
See p
oste
r by A
. Arrie
ta
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
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)
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 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
24
dyn 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
MeR=1e-3 Me
R=2e-3
MeR=5e-3 Me
R=1e-2
Data
LMC PNe SMC Pne
Modelstwind
tnucl
ttr
27
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)
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 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
Planetary nebulae beyond the Milky Way - May 19-21, 2004 29
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
30
Observed distributions of I(5007)/I(Hb)LMC
SMC
31
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
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
Fain
t---
----
--->
bri
gh
t
35
CSs in PNLF
LMC
SMC
Fain
t-----------> b
right
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 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
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.
·