Magellanic Cloud planetary nebulae as probes of stellar
Magellanic Cloud planetary nebulae as probes of stellar evolution and populations Letizia Stanghellini Planetary nebulae beyond the Milky Way - May 1921, 2004 1
Magellanic Cloud PNe The known distances, low field reddening, relative proximity, and metallicity range make them v. Absolute probes of post-AGB evolution v. Benchmarks for extragalactic PN populations Planetary nebulae beyond the Milky Way - May 19 -21, 2004 2
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 3
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 4
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? Planetary nebulae beyond the Milky Way - May 19 -21, 2004 5
Round PNe (R) are a minority (22 % of all Galactic PNe with studied morphology) Symmetric 49% elliptical (E) | Asymmetric 17% bipolar (or multi-polar) (B) 9% have an equatorial enhancement, or ring (lobe -less bipolar, or bipolar cores) (BC) 3% point-symmetric 6
HST and spatial resolution LMC SMP 10 HST STIS -----3 arcsec ------- ------35 arcsec ----------- 7
Slitless Spectra of LMC SMP 16 G 430 M (4818— 5104) and G 750 M (6295— 6867) _5007 [O III] _4959 [O III] _4861 Hb _6300 [O I] 6584 [N II] 6563 Ha 6548 [N II] 6732 [S II] 6716 [S II] 8
Galaxy LMC Symmetric Round Elliptical | Asymmetric Bipolar Point-symmetric 9
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% 10
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 nonmagnetic WDs! Wickramasinge & Ferrario 2000) • Binary evolution of the progenitor (CE)? Morris 81; Soker 98 11
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 Planetary nebulae beyond the Milky Way - May 19 -21, 2004 12
Primordial elements, LMC O Round * Elliptical Bipolar core Bipolar LMC HII regions (average) 13
Primordial elements, LMC O Round * Elliptical Bipolar core Bipolar LMC HII regions (average) 14
LMC PN morphology and the products of stellar evolution O Round * Elliptical Bipolar core Bipolar LMC HII regions (average) 15
Decreasing excitation class ---> SMP 16 SMP 95 SMP 34 Si IV N IV C IV] He II 16
[Ne IV] SMP 16 SMP 95 SMP 34 C III ] C II] 17
Optical AND UV morphology Broad band C III]1908 LMC SMP 95 [O III] 5007 [N II] Ha [N II] C II] 2327 [Ne IV] 2426 nebular continuum 18
UV spectra fitting Planetary nebulae beyond the Milky Way - May 19 -21, 2004 19
P-Cygni profiles Planetary nebulae beyond the Milky Way - May 19 -21, 2004 20
See poster by A. Arrieta Wind momentum vs. luminosity 21
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 · Me. R (residual envelope mass at EEQ) determines ttr · tdyn =DPN/vexp represent the dynamic PN age. If DPN is measured on main shell, tdyn tracks time from EEQ · tdyn =ttr+ tev (tev= time after PN illumination, corresponding to evolutionary time if tracks have zero point at illumination) 22
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 Planetary nebulae beyond the Milky Way - May 19 -21, 2004 23
tdyn and tev LMC SMC Round: symm. PNe (R, E) Square: asymm. PNe (B, BC, P) H-burning central stars 24
Distribution of ttr in MC PNe 25
Me. R=1 e-3 Me. R=2 e-3 Data LMC PNe SMC Pne Me. R=5 e-3 Me. R=1 e-2 Models twind tnucl ttr 26
Total mass loss (IMFMR) Data: optically 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) 27
Importance of spatiallyresolved PN populations · We sampled ~50 (+30) LMC and ~30 SMC PNe, chosen among the brightest known (based on on Hb 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 28
MA 1796 Log Fb C Size [arcsec] Size [pc] -13. 85 1. 53 3 0. 85 MA 1797 MG 2 . . . 11 3. 1 -14. 3 1. 4 3. 5 0. 98 Planetary nebulae beyond the Milky Way - May 19 -21, 2004 29
Observed distributions of I(5007)/I(Hb) LMC SMC 30
Cloudy models Galaxy LMC SMC 31
PN cooling in different galaxies Our HST data: LMC <I(5007)/I(Hb)>=9. 4 (3. 1) <I(1909)/I(Hb)>=5 (5) SMC <I(5007)/I(Hb)>=5. 7 (2. 5) UV: Cycle 13 SMC LMC Galaxy 33
PNe in the PNLF O round; * elliptical; bipolar core; bipolar SMC Open circles: R Asterisks: E Triangles: BC Squares: B Filled circles: P Faint-----> bright LMC 34
CSs in PNLF SMC Faint------> bright LMC SMC HLCO LMC HLCO 35
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 36
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]/Hb flux ratio of a PN population variant with host galaxy Planetary nebulae beyond the Milky Way - May 19 -21, 2004 37
Summary, cont. • Symmetric PNe populate the high luminosity parts of · the PNLF • High mass CSs populate the faint end of the LF, sample to be extended Planetary nebulae beyond the Milky Way - May 19 -21, 2004 38
- Slides: 37