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Physics and Chemistry of Gas in Planetary Nebulae

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Physics and Chemistry of Gas in Planetary Nebulae RIJKSUNIVERSITEIT GRONINGEN Physics and Chemistry of Gas in Planetary Nebulae PROEFSCHRIFT ter verkrijging van het doctoraat in de Wiskunde en Natuurwetenschappen aan de Rijksuniversiteit Groningen op gezag van de Rector Magnificus, dr. F. Zwarts, in het openbaar te verdedigen op dinsdag 30 september 2003 om 13.15 uur door Jeronimo´ Bernard Salas geboren op 4 september 1975 te Cordoba,´ Spanje Promotor: Prof. dr. A.G.G.M. Tielens Co-promotor: Dr. P.R. Wesselius Beoordelingscommissie: Prof. dr. M.J. Barlow Prof. dr. L.B.F.M. Waters Prof. dr. J.M. van der Hulst ISBN-nummer: 90-367-1896-1 To my parents Cover Image: Planetary Nebula M 57, also known as the Ring Nebula. Image credit: Hubble Heritage Team (AURA/STScI/NASA). Back-cover Image: Planetary Nebula MyCn18, an Hourglass Nebula. Image credit: Raghven- dra Sahai and John Truger (JPL), the WFPC2 science team and NASA. Contents 1 Introduction 1 1.1 Evolution of low and intermediate mass stars : : : : : : : : : : : : : : : : 2 1.1.1 From the cradle to the grave : : : : : : : : : : : : : : : : : : : : : 2 1.1.2 Nucleosynthesis : : : : : : : : : : : : : : : : : : : : : : : : : : : 3 1.1.3 Mixing episodes during the evolution : : : : : : : : : : : : : : : : 3 1.2 Planetary Nebulae : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 4 1.2.1 PNe and the chemical enrichment of the ISM : : : : : : : : : : : : 4 1.2.2 Importance of PNe : : : : : : : : : : : : : : : : : : : : : : : : : 5 1.2.3 Neutral material around PNe : : : : : : : : : : : : : : : : : : : : 5 1.2.4 PNe in a general context : : : : : : : : : : : : : : : : : : : : : : : 6 1.3 Physics in PNe : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 7 1.3.1 The spectrum : : : : : : : : : : : : : : : : : : : : : : : : : : : : 7 1.3.2 Electron density and temperature, and abundances : : : : : : : : : 8 1.4 Studying PNe in the infrared : : : : : : : : : : : : : : : : : : : : : : : : : 10 1.5 In this thesis : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 12 2 The ISO–SWS Spectrum of Planetary Nebula NGC 7027 13 2.1 Introduction : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 14 2.2 ISO observations : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 14 2.3 Data reduction : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 15 2.4 Line flux discussion : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 16 2.5 The visual and the ultraviolet spectrum : : : : : : : : : : : : : : : : : : : 18 2.6 Analysis : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 21 2.6.1 Electron density : : : : : : : : : : : : : : : : : : : : : : : : : : : 21 2.6.2 Electron temperature : : : : : : : : : : : : : : : : : : : : : : : : 22 2.6.3 Abundances : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 23 2.7 Discussion : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 26 2.7.1 Missing stages of ionization : : : : : : : : : : : : : : : : : : : : : 26 2.7.2 Physical parameters : : : : : : : : : : : : : : : : : : : : : : : : : 27 2.7.3 Abundances with recombination lines : : : : : : : : : : : : : : : : 27 2.7.4 Abundances and progenitor : : : : : : : : : : : : : : : : : : : : : 28 2.8 Conclusions : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 28 vi CONTENTS 3 An ISO and IUE study of Planetary Nebula NGC 2440 31 3.1 Introduction : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 32 3.2 ISO and IUE observations : : : : : : : : : : : : : : : : : : : : : : : : : : 32 3.3 Corrections to line fluxes : : : : : : : : : : : : : : : : : : : : : : : : : : 33 3.3.1 Extinction : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 33 3.3.2 Aperture corrections : : : : : : : : : : : : : : : : : : : : : : : : : 34 3.4 Line fluxes : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 35 3.4.1 Infrared spectrum : : : : : : : : : : : : : : : : : : : : : : : : : : 35 3.4.2 Ultraviolet spectrum : : : : : : : : : : : : : : : : : : : : : : : : : 36 3.4.3 Optical data : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 39 3.5 Physical parameters : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 39 3.5.1 Analysis : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 39 3.5.2 Discussion : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 41 3.6 Chemical abundances : : : : : : : : : : : : : : : : : : : : : : : : : : : : 42 3.6.1 Analysis : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 42 3.6.2 Discussion of the abundances : : : : : : : : : : : : : : : : : : : : 45 3.7 Conclusions : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 46 4 Abundances of Planetary Nebulae BD+30 3639 and NGC 6543 49 4.1 Introduction : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 50 4.1.1 BD+30 3639 : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 50 4.1.2 NGC 6543 : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 50 4.1.3 Layout of this chapter : : : : : : : : : : : : : : : : : : : : : : : : 51 4.2 Observations and data reduction : : : : : : : : : : : : : : : : : : : : : : : 51 4.2.1 ISO observations : : : : : : : : : : : : : : : : : : : : : : : : : : 51 4.2.2 Ultraviolet and optical observations : : : : : : : : : : : : : : : : : 52 4.3 Aperture corrections : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 53 4.4 Infrared spectrum and extinction : : : : : : : : : : : : : : : : : : : : : : 54 4.4.1 BD+30 3639 : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 54 4.4.2 NGC 6543 : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 57 4.5 The visual and the ultraviolet spectrum : : : : : : : : : : : : : : : : : : : 57 4.5.1 BD+30 3639 : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 58 4.5.2 NGC 6543 : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 60 4.6 Physical conditions : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 60 4.6.1 Electron density : : : : : : : : : : : : : : : : : : : : : : : : : : : 61 4.6.2 Electron temperature : : : : : : : : : : : : : : : : : : : : : : : : 61 4.7 Abundances : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 62 4.7.1 BD+30 3639 : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 62 4.7.2 NGC 6543 : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 64 4.7.3 Inhomogeneities in NGC 6543 : : : : : : : : : : : : : : : : : : : 66 4.8 Conclusions : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 67 CONTENTS vii 5 Probing AGB nucleosynthesis via accurate Planetary Nebula abundances 69 5.1 Introduction : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 70 5.2 Sample of PNe : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 72 5.2.1 General : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 72 5.2.2 HR diagram : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 74 5.3 Accurate abundances of ISO-observed PNe : : : : : : : : : : : : : : : : : 75 5.3.1 Abundances : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 75 5.3.2 Comparison with Solar abundances : : : : : : : : : : : : : : : : : 78 5.4 Nucleosynthesis in low- and intermediate-mass stars : : : : : : : : : : : : 79 5.5 Synthetic TP-AGB calculations : : : : : : : : : : : : : : : : : : : : : : : 79 5.5.1 Nucleosynthesis and mixing assumptions of the TP-AGB model : : 81 5.6 Comparison between models and observations : : : : : : : : : : : : : : : 83 5.6.1 The starting point: TP-AGB models with solar-scaled molecular opacities : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 83 5.6.2 Sub-grouping of the ISO sample and comparison with other PNe data 83 5.6.3 PNe with “normal” He abundances : : : : : : : : : : : : : : : : : 86 5.6.4 PNe with extremely high He abundance : : : : : : : : : : : : : : : 92 5.7 Summary and conclusions : : : : : : : : : : : : : : : : : : : : : : : : : : 103 6 Physical Conditions in PDRs around Planetary Nebulae 107 6.1 Introduction : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 108 6.2 Observations : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 109 6.3 Reduction techniques : : : : : : : : : : : : : : : : : : : : : : : : : : : : 110 6.4 General parameters of the PNe : : : : : : : : : : : : : : : : : : : : : : : 111 6.4.1 HR diagram : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 113 6.5 The SWS and LWS spectra : : : : : : : : : : : : : : : : : : : : : : : : : 114 6.6 Lines fluxes : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 116 6.6.1 Analysis of the atomic lines : : : : : : : : : : : : : : : : : : : : : 116 6.6.2 Background contamination and aperture corrections : : : : : : : : 116 6.7 Physical conditions of the PDRs : : : : : : : : : : : : : : : : : : : : : : : 119 6.7.1 G0 and the FIR flux : : : : : : : : : : : : : : : : : : : : : : : : : 119 6.7.2 Comparison with PDR models : : : : : : : : : : : : : : : : : : : 121 6.8 PDRs versus Shocks : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 126 6.9 H2 in NGC 7027, Hb 5 and NGC 6302 : : : : : : : : : : : : : : : : : : : : 128 6.9.1 Method : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 128 6.9.2 Discussion : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 128 6.10 Atomic, ionized and molecular mass : : : : : : : : : : : : : : : : : : : : 129 6.11 General discussion : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 132 6.12 Summary and Conclusions : : : : : : : : : : : : : : : : : : : : : : : : : 137 7 Conclusions and future work
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