thesis - IRS, The Infrared Spectrograph

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Table 3.3–. Continued.λ Ident. Flux 1 Flux 2 Flux 3 λ Ident. Flux 1 Flux 2 Flux 3(nm) HR LR (nm) HR LR171.10 Si II 0.630 7.36 14.43 ∗ 286.96 ? 0.13 0.82 1.61171.68 S III? 0.42 4.89 9.59 290.14 C IV 0.12 0.74 1.46174.71 N III] 0.48 10.1 115.60 226.57 292.95 [Mg V] 0.21 1.27 2.50174.90 N III] 0.71 302.50 O III 0.21 0.15 0.86 1.68175.00 N III] 4.07 304.86 O III 1.03 1.22 6.88 13.49175.24 N III] 2.19 313.44 O III 7.15 7.88 42.36 83.03175.43 N III] 0.45 320.47 He II 2.69 3.88 20.10 39.39180.49 [Ne III] 0.450 5.11 10.01Flux 1 : Observed flux; HR= High Resolution Spectra; LR= Low Resolution Spectra.Flux 2 : Dereddened flux.Flux 3 : Dereddened and aperture corrected flux (Aperture factor is 1.96).∗ Taken from Shields et al. (1981).: Noisy.38 CHAPTER 3: An ISO and IUE study of Planetary Nebula NGC 2440
3.5. Physical parameters 393.4.3 Optical dataTogether with the infrared and ultraviolet data, optical lines were also used to derive thephysical parameters of the nebula, and to have information on some unobserved stages ofionization. The observed fluxes were taken from Hyung & Aller (1998), and corrected forreddening. The Ne V line flux given by Rowlands et al. (1993) was also used. Table 3.4 liststhe optical lines used.For N II line fluxes at 575.5 and 658.4 nm, given by Perinotto & Corradi (1998), have beenincluded. They measure the flux in different regions of the nebula: from the center (cen), topositive increasing distances from the center (p1,p2, etc...) and negative increasing distances(n1,n2, etc...), relative to the orientation defined by the position angle of their observations(see Perinotto & Corradi 1998, for details). The average values used in this paper correspondto the cen+p1+n1 regions which agree with the region observed by ISO–SWS and IUE.3.5 Physical parametersIn this section the electron temperature and density are analyzed.3.5.1 AnalysisElectron densityN e has been derived for nine ions. A T e =15 000 K has been assumed and a justification forthis choice is given in the following subsection. The N e is shown in Table 3.5, and as canbe seen, N e seems to be constant for all the ions except for S III and Ar V. For comparison,the N e found by Keenan et al. using the R-matrix method in successive papers in 1996,1997, 1998 and 1999 for S II, Ar IV, Ne IV and O II respectively have been included in thetable, which average to 4000 cm −3 . Hyung & Aller (1998) give an average N e of 5000cm −3 . If the average N e is derived from Table 3.5, excluding S III and Ar V, a value of 4500cm −3 is found. This is in good agreement with the N e given by Hyung & Aller (1998)and Keenan et al. (1996, 1997, 1998, 1999) and therefore has been adopted to derive theT e and abundances. N e derived from S III and Ar V differs by a large amount from the restof the ions. This could be due to the fact that the argon line at 13.01 µm and especially thesulfur line at 33.47 µm are very noisy. The N e has been derived for several ions which havedifferent ionization potential (IP). This value seems to be constant, about 4500 cm −3 ; thereis no trend with IP.Electron temperatureTo derive T e the ratio of lines originating from levels that differ by several electron volts areneeded. An N e =4500 cm −3 has been assumed.T e has been derived for thirteen different ions and the values are shown in Table 3.6. Thetemperatures are plotted versus the ionization potential in Fig. 3.2. The curve shows a trendof T e with IP.The T e derived from N II differs by 1400 K depending on whether the optical lines fromHyung & Aller (1998) or Perinotto & Corradi (1998) are used. Both values are shown in
Page 1 and 2: RIJKSUNIVERSITEIT GRONINGENPhysics
Page 3 and 4: To my parents
Page 5 and 6: Contents1 Introduction 11.1 Evoluti
Page 7 and 8: CONTENTSvii5 Probing AGB nucleosynt
Page 9 and 10: 1IntroductionPLANETARY NEBULAE are
Page 11 and 12: 1.1. Evolution of low and intermedi
Page 13 and 14: 1.2. Planetary Nebulae 5Flash−Dri
Page 15 and 16: 1.3. Physics in PNe 7their whole li
Page 17 and 18: 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: Table 3.3-. IUE intensities, fluxes
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
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5.6. Comparison between models and
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5.7. Summary and conclusions 103Fig
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5.7. Summary and conclusions 105A s
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6Physical Conditions in PDRs around
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6.2. Observations 109are not promin
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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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