thesis - IRS, The Infrared Spectrograph

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62 CHAPTER 4: Abundances of Planetary Nebulae BD+30 3639 and NGC 65438250 K respectively. For the purpose of this work an T e =8500 K is assumed throughout thepaper.For NGC 6543 six ions were used to derive T e . N II (which has a lower IP than the otherions) gives a higher temperature (around 9000 K) than the rest of the ions which average outto 7800 K. The indication of the N II needs to be confirmed. For the rest of the paper anaverage T e =8200 K of all ions is assumed for NGC 6543.4.7 AbundancesIn Table 4.10 ionic and elemental abundances for BD+30 3639 and NGC 6543 are given.For most ions no abundance estimates for unseen stages of ionization are needed, thus theIonization Correction Factor (ICF) is 1. In Table 4.11, these abundances are compared withthose found in the Sun, O–B stars, and in previous studies.The helium abundances have been determined comparing the measured optical lines ofHe II at 468.6 nm and He I at 447.1 and 587.6 nm, with theoretical predictions of Benjaminet al. (1999). The comparison with theory has been done for N e =10 000 cm −3 and aninterpolation temperature of 8500 K for BD+30 3639 and 8200 K for NGC 6543.Taking into account the flux error the error in the abundances amounts to 10-25% forall elements except helium. Other errors are difficult to quantify, such as those caused byatomic parameters (especially collisional strengths). Care was take when selecting them (seeBernard Salas et al. 2002, chapter 3). The use of ionization correction factors also introducessome uncertain error which increases with the ICF. In this study the ICF were usuallyunnecessary but when needed were very small and therefore do not contribute much to theerror. A quantitative idea of the error can be inferred in several ways. The present abundancesare in most cases within 30% of other studies (except that of the carbon). The ionicabundances were derived in many cases using more than one line and these are consistentwith each other to within 30%. Argon and sulfur are elements not supposed to change in thecourse of evolution of intermediate mass stars. A comparison of these elements with otherPNe in the literature agree within 30%. We therefore think that 30% is a good estimate forthe error on the abundances of all elements with the exception of the nitrogen in NGC 6543,which is around 50%. The main nitrogen contribution in NGC 6543 comes from N ++ . Thisionic abundance has been derived from the 57.3 µm and 175.0 nm lines and is 3.1(-4) 1 and1.2(-4) respectively. Unfortunately the infrared line is density dependent and the ultravioletline is temperature dependent, making it difficult to assess which one gives the best value, andincreasing therefore the error. In this work an averaged N ++ ionic abundance from the infraredand ultraviolet lines has been used, an a larger error assumed. The error on the heliumabundance for NGC 6543 is around 7%.4.7.1 BD+30 3639The elemental abundances for seven elements have been derived. High stages of ionizationare not seen, as expected. To investigate their possible contribution upper limits for theunseen N ++ , Ne ++ , S 3+ and Cl 3+ were derived. Even a contribution to the abundance equal1 In this section and Tables 4.10, 4.11 and 4.12 the number in parenthesis means: x(y) = x × 10 y .
Table 4.10–. Ionic concentrations and chemical abundances.Ion λ BD+30 3639 NGC 6543∑(nm) N ion /N p Nion /N p ICF ♮ ∑N elem. /N p N ion /N p Nion /N p ICF ♮ N elem. /N pHe 0 447.2, 587.5 0.061 ⋆ 0.118 ⋆He + 468.6 4.0(-5) ⋆ 0.118 1 0.118C + 232.5 6.49(-4) 2.34(-5)C ++ 190.9 8.42(-5) 7.33(-4) 1 7.3(-4) 1.89(-4) 2.12(-4) 1.2 2.5(-4)N o 519.7, 520.0 2.16(-6)N + 575.5, 658.4 1.07(-4) 8.70(-6)N ++ 57 300,174.5 < 1.70(−5) 2.13(-4)N 3+ 148.5 1.09(-4) 1 1.1(-4) 1.13(-5) 2.33(-4) 1 2.3(-4)O o 630.0, 636.3 5.32(-6)O + 372.7 4.47(-4) 1.99(-5)O ++ 495.9, 500.7 4.13(-6) 5.26(-4)O 3+ 25890 4.56(-4) 1 4.6(-4)
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RIJKSUNIVERSITEIT GRONINGENPhysics
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To my parents
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Contents1 Introduction 11.1 Evoluti
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CONTENTSvii5 Probing AGB nucleosynt
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1IntroductionPLANETARY NEBULAE are
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1.1. Evolution of low and intermedi
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1.2. Planetary Nebulae 5Flash−Dri
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1.3. Physics in PNe 7their whole li
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1.3. Physics in PNe 95.35 eVO IIIλ
Page 19 and 20: 1.4. Studying PNe in the infrared 1
Page 21 and 22: 2The ISO-SWS Spectrum ofPlanetary N
Page 23 and 24: 2.3. Data reduction 15Table 2.1-. C
Page 25 and 26: 2.4. Line flux discussion 17Table 2
Page 27 and 28: 2.5. The visual and the ultraviolet
Page 29: 2.6. Analysis 21Table 2.5-. Electro
Page 32 and 33: 24 CHAPTER 2: The ISO-SWS Spectrum
Page 39 and 40: 3An ISO and IUE study of PlanetaryN
Page 41 and 42: 3.3. Corrections to line fluxes 33[
Page 43 and 44: 3.4. Line fluxes 35Table 3.1-. Comp
Page 45 and 46: Table 3.3-. IUE intensities, fluxes
Page 47 and 48: 3.5. Physical parameters 393.4.3 Op
Page 49 and 50: 3.5. Physical parameters 41Table 3.
Page 51 and 52: 3.6. Chemical abundances 43Table 3.
Page 53 and 54: 3.6. Chemical abundances 45Table 3.
Page 55: 3.7. Conclusions 47Acknowledgements
Page 58 and 59: 50 CHAPTER 4: Abundances of Planeta
Page 77 and 78: 5Probing AGB nucleosynthesis viaacc
Page 79 and 80: 5.1. Introduction 71about the synth
Page 81 and 82: Table 5.2-. Radius, Zanstra tempera
Page 83 and 84: 5.3. Accurate abundances of ISO-obs
Page 85 and 86: 5.3. Accurate abundances of ISO-obs
Page 87 and 88: 5.4. Nucleosynthesis in low- and in
Page 89 and 90: 5.5. Synthetic TP-AGB calculations
Page 91 and 92: 5.6. Comparison between models and
Page 111 and 112: 5.7. Summary and conclusions 103Fig
Page 113 and 114: 5.7. Summary and conclusions 105A s
Page 115 and 116: 6Physical Conditions in PDRs around
Page 117 and 118: 6.2. Observations 109are not promin
Page 119 and 120: 6.4. General parameters of the PNe
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6.4. General parameters of the PNe
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Table 6.3-. Radius, Zanstra tempera
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6.6. Lines fluxes 117Figure 6.2-. S
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6.7. Physical conditions of the PDR
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6.8. PDRs versus Shocks 127Figure 6
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6.10. Atomic, ionized and molecular
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6.10. Atomic, ionized and molecular
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6.11. General discussion 133Table 6
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6.11. General discussion 135Figure
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6.12. Summary and Conclusions 137su
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7Conclusions and future workTHE res
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141• PNe with He/H > 0.14. The st
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143HERSCHEL The launch of this sate
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Nederlandse SamenvattingSTERREN wor
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Nederlandse Samenvatting 147Figuur
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Nederlandse Samenvatting 149PHOTOIO
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Nederlandse Samenvatting 151Figuur
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Nederlandse Samenvatting 153infraro
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English SummarySTARS are born, live
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English Summary 157Figure 2-. Two e
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English Summary 159PHOTOIONIZATIONR
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English Summary 161Figure 5-. Spect
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English Summary 163all) stages of i
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BibliographyAcker A., Marcout J., O
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BIBLIOGRAPHY 167Henry R.B.C., Kwitt
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BIBLIOGRAPHY 169Pottasch S.R., Bern
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List of PublicationsPublications in
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AcknowledgementsI could easily writ
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Acknowledgements 175sense of humor,
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