W.J. Maciel, R.D.D. Costa, T.E.P. Idiart IAG/USP – São Paulo - Brazil Extra-galactic Planetary Nebulae Workshop Garching, May 2004 CHEMICAL COMPOSITION OF PLANETARY NEBULAE: MAGELLANIC CLOUDS AND THE GALAXY 06.05.2004 W.J. Maciel, R.D.D. Costa, T.E.P. Idiart IAG/USP – São Paulo - Brazil

ABSTRACT We compare the chemical composition of planetary nebulae in three different systems: the Galaxy, the Large Magellanic Cloud (LMC) and the Small Magellanic Cloud (SMC). The data has been gathered by the IAG/USP group during the last decade in a homogeneous procedure, emphasizing distance-independent correlations. We show that most abundance correlations hold for all three systems, taking into account the observed metallicity differences between the Galaxy and the Magellanic Clouds.

PLAN OF THE TALK 1. Introduction 2. The data 3. Distance-independent correlations 3.1 Planetary nebulae and HII regions 3.2 Correlations with S, Ar, Ne and O 3.3 Correlations with N 3.4 Correlations with He 4. Anticenter PN: the radial gradient 5. PN in the galactic bulge

1. Introduction Several hundred planetary nebulae have been detected in the Magellanic Clouds. However, accurate abundances are available only for a fraction of these objects. In this work, we will discuss some recent results on the chemical composition of planetary nebulae in three different systems: the Milky Way (MW), the Large Magellanic Cloud (LMC) and the Small Magellanic Cloud (SMC). We will emphasize our own results and distance–independent correlations, but will also try to relate the low metallicity systems LMC/SMC with the metal poorer regions of the galactic anticenter.

2. The data In the last decade, the chemical compositions of almost three hundred planetary nebulae have been determined by the IAG/USP group, using both the 1.52 m ESO telescope at La Silla and the 1.6 m LNA telescope at Brasopolis, Brazil. The main characteristics of this work are the high degree of homogeneity of the observational and reduction procedures, and in the analysis of the chemical abundances.

PN in the dataset of the IAG/USP group

3. Distance-independent correlations 3.1 Planetary nebulae and HII regions The abundances of elements such as He, S, Ne, Ar, and O are similar both in the PN and HII regions of each system. The main differences appear for Nitrogen, which is dredged up in the PN progenitor stars.

Average abundances of PN and HII regions

Abundance differences: PN minus HII regions figure 1 Abundance differences: PN minus HII regions

3. Distance-independent correlations 3.2 Correlations with S, Ar, Ne and O The elements S, Ar and Ne are not expected to be produced by the PN progenitor stars. Oxygen may have been somewhat altered by ON cycling, as we will investigate later. Whenever applicable, we will compare our data with the results of the extensive survey by Stasinska et al. (1998, Astron. Astrophys. 336, 667) .

Sulphur: the S/H x O/H correlation figure 2 Sulphur: the S/H x O/H correlation

Argon: the Ar/H x O/H correlation figure 3 Argon: the Ar/H x O/H correlation

Neon: the Ne/H x O/H correlation figure 4 Neon: the Ne/H x O/H correlation

3. Distance-independent correlations 3.3 Correlations with N As we have seen, nitrogen is dredged up in the progenitor stars, so that its abundance has been altered with relation to the interstellar values. Some N/O x O/H anticorrelation is observed, as reported by some authors, especially for the LMC and SMC nebulae. This is also reflected in the N/H x O/H correlation. Nitrogen can also be used in the comparison of the observed N/O x N/H correlation with the relation predicted by theoretical models for the LMC (Groenewegen and de Jong, A&A 282, 127, 1994).

Nitrogen: the N/O x O/H anticorrelation figure 5a Nitrogen: the N/O x O/H anticorrelation

Nitrogen: the N/O x O/H anticorrelation figure 5b Nitrogen: the N/O x O/H anticorrelation

Nitrogen: the N/O x O/H anticorrelation figure 5c Nitrogen: the N/O x O/H anticorrelation

Nitrogen: the N/O x O/H anticorrelation figure 5d Nitrogen: the N/O x O/H anticorrelation

Nitrogen: the N/O x O/H anticorrelation figure 5e Nitrogen: the N/O x O/H anticorrelation

Nitrogen: the N/H x O/H correlation figure 6a Nitrogen: the N/H x O/H correlation

Nitrogen: the N/H x O/H correlation figure 6b Nitrogen: the N/H x O/H correlation

Nitrogen: the N/O x N/H correlation and model - - - Groenewegen and de Jong (1994) figure 7a Nitrogen: the N/O x N/H correlation and model

Nitrogen: the N/O x N/H correlation and model - - - Groenewegen and de Jong (1994) figure 7b Nitrogen: the N/O x N/H correlation and model

Nitrogen: the N/O x N/H correlation and model - - - Groenewegen and de Jong (1994) figure 7c Nitrogen: the N/O x N/H correlation and model

3. Distance-independent correlations 3.4 Correlations with He N/O and N/H correlations with He/H have been observed for PN in the three systems. These relations can be used to compare our abundances with the presumably more correct ISO abundances by Pottasch et al. (IAU Symposium 209, p. 353, 2003). We also compare these correlations with recent models and the ISO sample by Marigo et al. (Astron. Astrophys. 409, 619, 2003). We conclude that the same correlations are obtained, with a slightly larger dispersion.

Helium: the N/O x He/H correlation figure 8a Helium: the N/O x He/H correlation

Helium: the N/O x He/H correlation figure 8b Helium: the N/O x He/H correlation

Helium: the N/O x He/H correlation figure 8c Helium: the N/O x He/H correlation

Helium: the N/O x He/H correlation figure 8d Helium: the N/O x He/H correlation

Marigo et al. (2003) ISO sample (filled squares) figure 8e Marigo et al. (2003) ISO sample (filled squares)

Marigo et al. (2003) ISO sample (filled squares) figure 8f Marigo et al. (2003) ISO sample (filled squares)

Marigo et al. (2003) ISO sample – model predictions figure 9a Marigo et al. (2003) ISO sample – model predictions

Marigo et al. (2003) ISO sample – model predictions figure 9b Marigo et al. (2003) ISO sample – model predictions

Marigo et al. (2003) ISO sample – model predictions figure 9c Marigo et al. (2003) ISO sample – model predictions

Helium: the N/H x He/H correlation figure 10a Helium: the N/H x He/H correlation

Helium: the N/H x He/H correlation - - - Pottasch et al. (2003) Sun and Orion figure 10b Helium: the N/H x He/H correlation

Marigo et al. (2003) ISO sample - model predictions figure 10c Marigo et al. (2003) ISO sample - model predictions

Helium: the N/H x He/H correlation figure 10d Helium: the N/H x He/H correlation

Helium: the N/H x He/H correlation figure 10e Helium: the N/H x He/H correlation

4. Anticenter PN: the radial gradient Recently, Costa, Uchida and Maciel (A&A, in press 2004) have analyzed a sample of PN located in the galactic anticenter. It was shown that the observed radial O/H gradient tends to flatten out for large galactocentric distances, roughly R > 10 kpc, in agreement with previous results by Maciel and Quireza (A&A 345, 629, 1999). Therefore, it is interesting to investigate whether PN in the anticenter direction have abundances similar or larger than LMC/SMC objects.

figure 11 The O/H radial gradient for galactic PN. Costa, Uchida and Maciel (A&A, in press 2004)

Sulphur: the S/H x O/H correlation figure 12a (same as figure 2) Sulphur: the S/H x O/H correlation

Sulphur: the S/H x O/H correlation MW: Crosses R < 10 kpc Empty Squares, R > 10 kpc figure 12b (same as figure 2, separating inner and outer PN) Sulphur: the S/H x O/H correlation

Sulphur: the S/H x O/H correlation MW: Crosses R < 10 kpc Empty Squares, R > 10 kpc figure 12c (same as figure 2, separating inner and outer PN) Sulphur: the S/H x O/H correlation

Argon: the Ar/H x O/H correlation MW: Crosses R < 10 kpc Empty Squares, R > 10 kpc figure 13a (same as figure 3, separating inner and outer PN) Argon: the Ar/H x O/H correlation

Argon: the Ar/H x O/H correlation MW: Crosses R < 10 kpc Empty Squares, R > 10 kpc figure 13b (same as figure 3, separating inner and outer PN) Argon: the Ar/H x O/H correlation

5. PN in the galactic bulge Several of the correlations shown are also obeyed by galactic bulge PN, as recently shown by Escudero, Costa and Maciel (A&A 414, 211, 2004).

figure 14 The S/H x O/H correlation for galactic bulge PN Escudero, Costa and Maciel (A&A 414, 211, 2004).

figure 15 The Ar/H x O/H and Ne/H x O/H correlations for galactic bulge PN Escudero, Costa and Maciel (A&A 414, 211, 2004).

figure 16 The N/O x O/H anticorrelation for galactic bulge PN Escudero, Costa and Maciel (A&A 414, 211, 2004).

figure 17 The N/H x O/H correlation for galactic bulge PN Escudero, Costa and Maciel (A&A 414, 211, 2004).

Extra-galactic Planetary Nebulae Workshop Garching, May 2004 With thanks to: J. A. de Freitas Pacheco L. G. Lago M. M. Uchida A. V. Escudero THE END