thesis - IRS, The Infrared Spectrograph

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130 CHAPTER 6: Physical Conditions in PDRs around Planetary NebulaeFigure 6.8–. Molecular hydrogen excitation diagrams for NGC 7027, Hb 5 and NGC 6302. The solidlines represent the Boltzmann distribution fits to the pure rotational lines (solid diamonds) and thedashed dot dot line is a fit to the vibrational lines in NGC 6302. The symbols represent the differenttransitions: 0-0S → filled diamonds, 1-0O → Open diamonds,1-0Q → squares, 2-1O → circle.
6.10. Atomic, ionized and molecular mass 131Figure 6.9–. Comparison of H 2 column density and rotational temperature derived for NGC 7027,Hb 5 and NGC 6302 and a sample of young stellar objects from van den Ancker et al. (2000). TheHelix nebula (Cox et al. 1998) is also plotted.it is described in more detail by Castro-Carrizo et al. (2001). Essentially, for the conditionsin the PDRs associated with these PNe, the temperature of the atomic gas is well abovethe excitation energy of the level involved and the density is much higher than the criticaldensity. Moreover, the [C II] line is expected to be (marginally) optically thin and hence is agood measure for the total mass of gas emitting. The main uncertainty is associated with theadopted distances and carbon abundances.M(M ⊙ ) = 7.0F (C II)d 2 /X c (6.5)In Eq. 6.5 F (C II) is the flux of the 157.7 µm line in erg/cm 2 /s, d is the distance in kpc,and X c is the carbon abundance. This abundance has been taken from the same referencesas the extinction in Table 6.2. There is no carbon abundance for Hb 5 and Mz 3 and a valueof 4×10 −4 has been assumed. This is probably not a bad approximation since the distancedominates by far the error in the mass determination. Fong et al. (2001) include in theirequation a correction factor (F c ) which is needed when the excitation temperature (T ext ) islow. This factor becomes one when T ext ≫ 92 K. The rotational temperatures derived in theprevious section were much greater than 92 K and we have assumed that it is also probablythe same for the other PNe and therefore F c =1.The ionized mass has been calculated using the Hβ flux. The flux is related to the massin the following equation:T eM(M ⊙ ) = 11.06F (Hβ)d 2 (10 4 K )0.88 /N e (6.6)In this equation the electron density (N e ) and temperature (T e ) have been taken againfrom the same references as the extinction in Table 6.2 except for Mz 3 where T e and N ehave been taken from Quinn et al. (1996). Unfortunately for K 3-17 the mass could not be
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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
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1.4. Studying PNe in the infrared 1
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2The ISO-SWS Spectrum ofPlanetary N
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2.3. Data reduction 15Table 2.1-. C
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2.4. Line flux discussion 17Table 2
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2.5. The visual and the ultraviolet
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2.6. Analysis 21Table 2.5-. Electro
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24 CHAPTER 2: The ISO-SWS Spectrum
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3An ISO and IUE study of PlanetaryN
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3.3. Corrections to line fluxes 33[
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3.4. Line fluxes 35Table 3.1-. Comp
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Table 3.3-. IUE intensities, fluxes
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3.5. Physical parameters 393.4.3 Op
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3.5. Physical parameters 41Table 3.
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3.6. Chemical abundances 43Table 3.
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3.6. Chemical abundances 45Table 3.
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3.7. Conclusions 47Acknowledgements
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50 CHAPTER 4: Abundances of Planeta
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5Probing AGB nucleosynthesis viaacc
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5.1. Introduction 71about the synth
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Table 5.2-. Radius, Zanstra tempera
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5.3. Accurate abundances of ISO-obs
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5.3. Accurate abundances of ISO-obs
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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
Page 121 and 122: 6.4. General parameters of the PNe
Page 123 and 124: Table 6.3-. Radius, Zanstra tempera
Page 125 and 126: 6.6. Lines fluxes 117Figure 6.2-. S
Page 127 and 128: 6.7. Physical conditions of the PDR
Page 135 and 136: 6.8. PDRs versus Shocks 127Figure 6
Page 137: 6.10. Atomic, ionized and molecular
Page 141 and 142: 6.11. General discussion 133Table 6
Page 143 and 144: 6.11. General discussion 135Figure
Page 145 and 146: 6.12. Summary and Conclusions 137su
Page 147 and 148: 7Conclusions and future workTHE res
Page 149 and 150: 141• PNe with He/H > 0.14. The st
Page 151 and 152: 143HERSCHEL The launch of this sate
Page 153 and 154: Nederlandse SamenvattingSTERREN wor
Page 155 and 156: Nederlandse Samenvatting 147Figuur
Page 157 and 158: Nederlandse Samenvatting 149PHOTOIO
Page 159 and 160: Nederlandse Samenvatting 151Figuur
Page 161 and 162: Nederlandse Samenvatting 153infraro
Page 163 and 164: English SummarySTARS are born, live
Page 165 and 166: English Summary 157Figure 2-. Two e
Page 167 and 168: English Summary 159PHOTOIONIZATIONR
Page 169 and 170: English Summary 161Figure 5-. Spect
Page 171 and 172: English Summary 163all) stages of i
Page 173 and 174: BibliographyAcker A., Marcout J., O
Page 175 and 176: BIBLIOGRAPHY 167Henry R.B.C., Kwitt
Page 177 and 178: BIBLIOGRAPHY 169Pottasch S.R., Bern
Page 179 and 180: List of PublicationsPublications in
Page 181 and 182: AcknowledgementsI could easily writ
Page 183: Acknowledgements 175sense of humor,
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