Abundances and relation to PN morphological features

Antonio MampasoIAC, Tenerife. Spain

• Abundances and main shell morphology– Recent, accurate data and modeling

• Abundances in PNe halos

• Microstructures:– Cometary globules– Knots in H-deficient objects– Low-ionization microstructures: the case of NGC7009

• Conclusions

Round Elliptical Bipolar

• He/H = 0.102 ± 0.010 0.121 ± 0.015 0.136 ± 0.010

0.107 ± 0.010 0.115 ± 0.014 0.132 ± 0.015

-- -- 0.150 ± 0.040

• N/O = 0.27 ± 0.08 0.31 ± 0.15 1.30 ± 0.50

0.22 ± 0.06 0.33 ± 0.16 0.90 ± 0.21

-- -- 1.39 ± 1.02References: Manchado, 2003 (80 PNe)

Phillips, 2003 (75 PNe) Perinotto & Corradi, 1998

(15 BPNe)• Round PNe come from long living low-mass stars• Bipolar PNe come from more massive progenitors.

Abundances and main shell morphology

(from Phillips 2003)

Elliptical and Bipolar PNe peak at the same (high) N/H

He/H separates better the BPNe from the R & EPNe.

There are six BPNe with He/H above 0.16.

“… we conclude that the study of the statistical correlations between central stars and PN morphology has probably reached, in this form, its exploitation… The future is… better nebular analysis on the individual objects… to improve the elemental abundances… extending the analysis to UV [and IR] spectroscopy.”

(Stanghellini et al. 2002)

Bipolar PNe with very high He/H cannot be explained with current models (Perinotto & Corradi, 1998)

Accurate PNe abundances: Survey of recent results

Round PNe: A39 (Jacoby et al. 01), IC2165 and NGC5882 (Pottasch et al. 03a).

Low mass progenitors; less processing (He, N, C) than more structured PNe. Progenitors had different metallicities from solar to 2-3 times solar.

Elliptical PNe: NGC7662, NGC6741 (Pottasch et. al. 01a), NGC40, NGC6153 (Pottasch et. al. 03b), and NGC6543 (Hyung et al. 00; Bernard-Salas et. al. 03).

Low-mass progenitors; some show little processing (NGC7662) while other much more (NGC6543). Progenitors had different metallicities, from half solar to 2-3 solar.

Bipolar PNe: NGC6302, NGC6445, NGC6537, He2-111 (Pottasch et al. 00), NGC7027 (Bernard-Salas et al. 01) and Hb-5 (Pottasch et al. 03c)

Intermediate-mass progenitors, 3-4 M (NGC7027, NGC6445, and

possibly Hb-5) to larger than 4 M (NGC6302, NGC6537 and He2-111 ).

UV, optical and IR (ISO) data now allow 30% accuracy in abundances for C, N, O, Ne, S, and Ar; their ICFs are around unity. Helium abundance accuracy is around 5%. But targets are biased towards bright and nearby (0.5 to 2.5 kpc) PNe.

Accurate PNe abundances: Recent modeling.

Abundances for 10 PNe compared with surface stellar abundances from synthetic evolutionary models for the TP-AGB phase (Marigo et al. 03)

He and N are larger than Solar nucleosynthesis.Ar is around solar, as is C+N+O progenitors of roughly solar compositionS is lower than solar (!) Solar S abundance is suspicious.

Recent modeling

PNe with He/H lower than 0.15 come from AGB low and intermediate mass (0.9-4 Mo) stars of initial solar metallicity. Abundances of He, N and C are well explained with 1-st, possibly 2-nd, and 3-rd dredge-up processes.

PNe with He/H higher than 0.15 come from AGB intermediate mass (4-5 Mo) stars of initial subsolar (LMC) metallicity (!). Abundances (including the low O values) are explained with both the 3-rd dredge-up and HBB.

Two classes of PNe:PNe with He/H higher than 0.15have much less Carbon and Oxygen

Abundances for 10 PNe compared with surface stellar abundances from synthetic evolutionary models for the TP-AGB phase (Marigo et al. 03)

Abundances in PNe Halos

Helium and N/O abundances in 7 PNe (NGC6543, M1-46, NGC6720NGC6751, NCG6826, NGC5882 and NGC2438). N/O is half in the halosof NGC5882 and NGC6720 than in their main shells small enrichment and little effect from the 3-rd dredge-up (Guerrero & Manchado 1999).

Hydrodynamical simulations by Villaver et al. (02, 03) complicate the scenario: Halos can be chemically mixed with the ISM (5-20% for 5Moprogenitors; up to 20-70% for lower masses) and dynamically distorted and stripped (up to 70% of the halo mass is lost for relative velocities of 20 km/s).

What abundances are we measuring at the halos?

Chemical abundances of PNe microstructures A) Cometary Knots.No chemistry available. Indication of higher O, N abundances (or

larger Te) at the inner knots of NGC7293 (O´Dell et al. 01)

B) Knots in H-deficient objectsA30 (talk by B. Ercolano). A78 (Medina & Peña, 00):-The inner knots of A78 have no H (only He and metals) but O, N and

Ne abundances are typical of normal type II PNe (contrary to Manchado

et al. 1988). Gas ejected from CS after H-burning.-The outer knots of A78 have H and He, N/O and Ne/O normal. -Discovery of a H-deficient high velocity (130 km/s) knot colliding with

the outer shell.NGC5315 (Pottasch et al. 02) H-deficient CS in a PN with normal

abundances.

HST-NICMOS images show He-rich material ejected in opposite

directions He-rich microstructures (0.6 arcsec)

Chemical abundances of PNe microstructures: NGC7009

C) Microstructures of low ionization: the case of NGC7009

Discovered by Herschel. Spectra by Aller (1941), also the first to discover

N overabundance at K1 and K4 (Czysak & Aller, 1979).

Balick et al. (1994) measure N/H x5 larger at K1,K4 than at the rim

recent high velocity ejection of N-rich material (also in NGC6543 and NGC6826). N/O overabundance of up to x6 w.r.t. the cores!

10-yr old problem for theoreticians.

Gonçalves et al. (03): much less (x2) N and N/O overabundance for K1 and K4

NGC7009 [NII]

Movie from Sabbadin et al. (03)

Chemical abundances of PNe microstructures: NGC7009

ICF(N) large, uncertain, depending

on O+ risky at low-ionization zones(charge-exchange reactions: differentrates for O and N ). Alexander &Balick (1997); Gruenwald & Viegas (1998)

N+/O+ is less affected but…

Is the N/H and N/O overabundance in FLIERS real or a conspiracy?

Chemical abundances of PNe microstructures: NGC7009

MOCASSIN modeling (Ercolano et al. 03a) allows: Complex geometry & density. Possible abundance variations. Full 3-D Monte Carlo solving of radiation transfer for both stellar and diffuse radiation fields.

Distance (arcsec)

N+

/O+

K1

K4

First results for NGC7009 (Ercolano et al. 03b): Simple modeling with empirical parameters to check on the possible

charge-exchange effects on N+/O+ overabundance:

[ N+/O+]off/[ N+/O+]on = 1.13 (R1); 1.16 (J1); 1.18 (K1)

Charge exchange reactions appear unable to account for the N/O overabundances measured at the low-ionization knots.

R1J1

K2J2

R2

K3

Global statistical studies on chemical abundances of Round, Elliptical and Bipolar PNe are in general agreement with stellar evolution theory.

Accurate (30%) abundances are now available for around 20 PNe. Detailed comparison with state-of-the-art models shows encouraging agreement. The “age-metallicity” problem for PNe with very high He/H requires further investigation.

Conclusions

Abundances in PNe Halos are very difficult to measure; current, sparse, results indicate moderate (if any) underabundance in N/O. (But keep an eye to the ISM!)

N (and N/O) overabundances in Low Ionization Structures are a key to theirorigin. New results on the LIS of NGC7009 suggest that a moderate N/O overabundance is possibly real.

Parameters for MOCASSIN modeling of NGC7009:

Central star: BB of 82000 K and luminosity 2500 L @ distance 1 kpc

Geometry: Three components modeled: R1, ellipsoidal shell with constant density 4910 cm-3

J1, cylindrical jet with constant density 1155 cm-3

K1, disk-shaped knot perpendicular to J1; density 2300 cm-3

Temperature: self-consistently derived in each region from modeling.

Abundances: As empirically derived for each component, except N/H for K1 N/H = 1.15 10-4 (giving best fit for N lines in K1)

Charge-exchange reactions included (ON-model) or excluded (OFF-model)

RESULTS

ROUND PNe:

IC2165 and A39: O, S, Ar, Ne approx. 2-3 times less than the Sun. He is solar while N is x2 solar (A39) or x1 solar (IC2165) low-mass progenitors of subsolar metallicity (i.e old or formed in a chemically peculiar region).

NGC5882: O, S, Ar, Ne approx. solar. He and N also around solar while C is half solar. Little processing, during 1-st, and possibly 3-rd, dredge-up low-mass progenitor of solar metallicity.

ELLIPTICAL PNe:

NGC7662, NGC40, NGC6153, NGC6741: Their CSs have low luminosity

(1000 L or less) low-mass progenitors where only 1-st, and possibly 3-rd, dredge-up are expected. O, S, Ar, Ne abundances are in general agreement with progenitors of around solar metallicity (NGC40 and NGC6741), half solar (NGC6772) or 2-3 times solar (NGC6153 ). NGC40 is anomalously rich in C (x5 solar).

NGC6543: Its CS is more luminous (5700 L. Abundances are around solar

in all elements except N and C (x2 and x0.7 solar, resp.). Low mass (1 M ) progenitor.

Individual objects: Round and Elliptical

BIPOLAR PNe:Why every bipolar is unique? :conclusions from Pottasch et al. (2000):

…and some are very unique: comparison between Hb-5 and the group of BPNe NGC6302, NGC6445, NGC6537, and He2-111 (from Pottasch et al. 00):S, Ar, Cl should not change during evolution of intermediate-mass stars… but S is half, Ar is double, and Cl is equal in Hb-5 than in the four BPNe.

Individual objects: Bipolar

The following conclusions can be drawn:1. NGC 6537, He2-111 and NGC 6302 all had originally the same abundance as the Orion nebula.2. NGC 6445 originated with similar abundance of sulfur and argon, but had higher abundance of oxygen and carbon.3. NGC 6445 had originally an abundance of carbon and oxygen similar to the sun or possibly higher.4. NGC 7027 originally had abundance similar to the sun, but higher than the Orion nebula or B stars.5. The nitrogen abundance, both with respect to hydrogen as with respect to oxygen, is higher in the PN than in the sun, B stars or the Orion nebula. Nitrogen has been formed in the course of evolution in all the PN under discussion.6. Considerably more nitrogen has been formed in NGC 6537, NGC 6302 and He2-111 than in NGC 6445 or NGC 7027. The N/O ratio is a factor of 3-4 higher in the former nebulae.7. The helium abundance in the former three nebulae is clearly higher than in the Orion nebula, the sun and in NGC 7027. The situation is not clear with respect to NGC 6445.8. If, following the theoretical models of Marigo et al. (1996), the overabundance of nitrogen (and to a lesser extent of helium) indicate that the original mass of the central star of NGC 7027 was 3-4 M, the original mass of the central stars of NGC 6537, NGC 6302 and He2-111 must have been considerably higher. That of the central star of NGC 6445 appears to have been closer to that of NGC 7027.9. While 3 of the 4 bipolar nebulae whose abundance has been determined with the help of ISO spectra show extreme nitrogen enrichment, it is apparently not always true that bipolar structure can be equated with nitrogen enrichment.

(From Pottasch et al. 00)

3-D photoionization modeling (MOCASSIN) for NGC7009

R1

J1

K1

[ N+/O+]off

[ N+/O+]on

Balick et al. 94Hyung et al. 00

Manchado & Pottasch 1989

NGC6543

NOT image by Corradi & Gonçalves

(Auguste Compte 1835):“We understand the possibility of determining their shapes, their distances, their sizes and their movements; whereas we would never know how to study by any means their chemical composition...” *

Real conclusions

*(as long as telescope allocation panels keep turning down our proposals)

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