TRACING ABUNDANCES IN GALAXIES WITH THE SPITZER ...

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Electron Temperature and Density In order to derive abundances, we adopt two electron temperatures (Te): T[N II] for the low-ionization potential ions (Ar II, Ne II, S II, and O II), and T[O III] for the high-ionization potential ions. Table 3.7 gives the electron temperatures from the literature. When possible, our adopted T[N II] and T[O III] are an average of the values from the literature. If temperatures are not available in the literature, we assume the average value from the other GBPNe in the sample ( = 8100 K and = 10700 K). Abundances from IR lines depend only weakly on the adopted Te, and thus our assumption does not strongly affect our abundances — especially those of argon, neon, and sulfur which are mostly determined from IR lines. We determine electron densities (Ne) from IR line ratios of S III, Ne III, Ar III, Ar V, and Ne V (see Table 3.7). The S III line ratio gives the best estimate of Ne, and thus we adopt it for the abundance analysis. Densities determined from the other line ratios are more uncertain because they either rely on at least one line with a weak flux, or the density is outside the range of what the line ratio can accurately measure. The adopted Ne from the S III ratios have an average of 3500 cm −3 , and range from 1000 to 9200 cm −3 . Ionic and Total Abundances Table 3.8 lists the parameters used in determining the PNe ionic abundances. Note that we use a predicted Hβ flux from the IR H I lines in order to ensure that the hydrogen comes from within the same slit as the IR forbidden lines. Table 3.9 presents the ionic abundances themselves. In order to determine total elemental abundances, the ionic abundances for each element are summed. When the ionic abundance can be determined by more than one line, we choose the abundance(s) 69
from the most reliable line(s), and mark the lines used in Table 3.9. If necessary, the sum of the ionic abundances for each element is then multiplied by an ionization correction factor (ICF) to account for unobserved ions that are expected to be present. For argon, we apply an ICF for the nine objects for which Ar +3 is not observed. For neon, we apply an ICF for the four high ionization nebulae with unobserved Ne +3 . ICFs are generally small, and we can derive accurate total elemental abundances for many objects, especially for the elements of neon and sulfur whose abundances are derived mainly from IR lines and which rarely need ICFs. Table 3.10 presents the total elemental abundances. The Ar +3 abundance can only be determined directly from optical lines for two of the GBPNe (PNG000.7+03.2 and PNG006.0-03.6). However, the Ar +3 abundance cannot contribute a large amount because the abundance of Ar +4 always accounts for
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TRACING ABUNDANCES IN GALAXIES WITH
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TRACING ABUNDANCES IN GALAXIES WITH
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BIOGRAPHICAL SKETCH Shannon was bor
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ACKNOWLEDGEMENTS First and foremost
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thank my husband Ryan. The rest of
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3 Chemical Abundances and Dust in P
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LIST OF FIGURES 1.1 Diagram of the
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ditionally we find that these nebul
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seed nuclei relative to the β deca
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shape (Carollo et al., 2007). These
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Boltzmann velocity distribution cha
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etween recapture and photoionizatio
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a whole. Additionally, abundances f
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at the appropriate temperature and
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(a) 3.37 eV 1.40 eV 0.10 eV 0.04 eV
Page 31 and 32: (Iion), the radiative transition ra
Page 33 and 34: lines. For example, changing the ad
Page 35 and 36: Figure 1.4 Starburst99 synthetic sp
Page 37 and 38: Figure 1.5 Example of crystalline s
Page 39 and 40: H H H H H H H H H Anthanthrene C H
Page 41 and 42: year lifetime. Spitzer is in an Ear
Page 43 and 44: CHAPTER 2 THE SPITZER IRS INFRARED
Page 45 and 46: these elements than previous studie
Page 47 and 48: dust is seen in the spectrum. We se
Page 49 and 50: Figure 2.2 Close-ups of emission li
Page 51 and 52: 2.4 Optical and UV Data We compleme
Page 53 and 54: 2.5 Data Analysis Our goal is to ca
Page 55 and 56: 2.5.2 Electron Density We assume an
Page 57 and 58: Table 2.6 Electron temperatures ass
Page 59 and 60: O, N, and C. The helium ionic abund
Page 61 and 62: Barlow (1994) use UV lines for impo
Page 63 and 64: is a spherical nebula with a low ma
Page 65 and 66: CHAPTER 3 CHEMICAL ABUNDANCES AND D
Page 67 and 68: essential data on important ionizat
Page 69 and 70: are members of the Bulge, (Acker et
Page 71 and 72: Table 3.2 Properties of observed GB
Page 73 and 74: nod-averaged line fluxes. Uncertain
Page 75 and 76: Table 3.3 Multiplicative scaling fa
Page 77 and 78: Table 3.4 Observed infrared line fl
Page 79 and 80: 3.5 Data Analysis 3.5.1 Abundances
Page 81: Table 3.6 Comparison of the derived
Page 85 and 86: Table 3.7 Electron temperatures and
Page 87 and 88: Table 3.9 Ionic abundances Ion x a
Page 89 and 90: 3.5.2 Crystalline Silicates Crystal
Page 91 and 92: argon, neon, and sulfur tend to be
Page 93 and 94: Figure 3.2 Continuum subtracted spe
Page 95 and 96: Figure 3.3 Profiles of PAH features
Page 97 and 98: mean argon and sulfur abundances ar
Page 99 and 100: of two smaller than that of Simpson
Page 101 and 102: towards the Galactic Center. On the
Page 103 and 104: Table 3.14 Parameters of linear fit
Page 105 and 106: models that show how a binary compa
Page 107 and 108: y an outer dense O-rich torus, indi
Page 109 and 110: CHAPTER 4 ABUNDANCES IN H II REGION
Page 111 and 112: expect their abundance ratio to rem
Page 113 and 114: We extract spectra processed throug
Page 115 and 116: Figure 4.2 IRS spectra of H II regi
Page 117 and 118: IRS slits from these WIRC observati
Page 119 and 120: S IV) we employ is equal to Te(O +2
Page 121 and 122: Figure 4.3 M51 H II region Ne III/N
Page 123 and 124: Figure 4.4 shows a plot of the (Ne
Page 125 and 126: James Webb Space Telescope (JWST);
Page 127 and 128: Bernard-Salas, J. & Tielens, A. G.
Page 129 and 130: Edgar, R. G., Nordhaus, J., Blackma
Page 131 and 132: Hummer, D. G., Berrington, K. A., E
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Matsuura, M., Zijlstra, A. A., Mols
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Pradhan, A. K., Montenegro, M., Nah
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Vassiliadis, E. & Wood, P. R. 1993,
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TRACING ABUNDANCES IN GALAXIES WITH THE SPITZER ...

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