TRACING ABUNDANCES IN GALAXIES WITH THE SPITZER ...

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Table 2.2 Extinction corrected optical line fluxes relative to Hβ=100 from Milingo et al. (2002b) λ (˚A) Line Flux a λ (˚A) Line Flux a 3727 [O II] 5.1 b 6584 [N II] 1.0 3869 [Ne III] 103 6717 [S II] 0.1 4070 [S II] 1.1 6731 [S II] 0.1 4363 [O III] 16.4 7005 [Ar V] 0.1 4471 He I 3.3 7135 [Ar III] 4.8 4686 He II 40.3 7236 [Ar IV] 0.1 c 4740 [Ar IV] 4.7 7264 [Ar IV] 0.1 c 4959 [O III] 386 7323 [O II] 0.6 5007 [O III] 1173 7751 [Ar III] 1.2 5755 [N II] 0.1 b 9069 [S III] 2.5 6312 [S III] 0.5 9532 [S III] 5.2 6436 [Ar V] 0.1 b a Extinction corrected flux relative to Hβ=100. The Hβ flux in the same aperture is 724.4 × 10 −14 erg cm −2 s −1 (Milingo et al., 2002b). Flux uncertainties are � 10% unless otherwise noted. b Flux uncertainty � 50%. c Flux uncertainty � 25%. Table 2.3 Selected observed ultraviolet line fluxes λ (˚A) Line Flux a λ (˚A) Line Flux a 1241 N V 8.86 b 1907 C III] 2250 1483 N IV] 58.5 b 2326 C II] 12.6 b,c 1548 C IV 1900 2422 [Ne IV] 184 1640 He II 2180 2471 [O II] 4.77 b,d 1750 N III] 75.5 a Observed flux in units of 10 −14 erg cm −2 s −1 . Unless otherwise marked, all fluxes are from IUE low resolution spectra and have uncertainties of � 15%. b Flux from IUE high resolution spectra. c Flux uncertainty � 50%. d Flux uncertainty � 30%. 39
2.5 Data Analysis Our goal is to calculate element abundances in IC 2448. In order to do this, we must first determine the extinction toward and physical conditions within the nebula. We iterate to find self-consistent solutions for the electron density and temperature. Then we use the derived values of extinction, electron density, and electron temperature to derive ionic abundances. Finally we sum the observed ionization stages of each element to derive total elemental abundances. 2.5.1 Extinction Correction We calculate the amount of interstellar extinction in two ways. First, we compare the observed Hβ flux for the whole nebula with the Hβ flux predicted from infrared hydrogen recombination lines for case B recombination for a gas at Te = 10 000 K and Ne = 1000 cm −3 using the theoretical hydrogen recombination line ratios from Hummer & Storey (1987). The H I(7-6) and H I(11-8) are blended in the spectrum, and theoretically the H I(11-8) line should be 12.26% of the H I(7-6) line (Hummer & Storey, 1987); thus this amount is subtracted out before predicting the Hβ flux from the H I(7-6) line. The results are shown in Table 2.4. Using the average predicted Hβ flux from that table, and the total observed Hβ flux of 1410 × 10 −14 erg cm −2 s −1 (Acker et al., 1992), we obtain CHβ=0.33. The second method we use to determine the extinction is to compare the observed Hβ flux to that predicted by the 6 cm radio flux using the following equation from Pottasch (1984): F (Hβ) = S6cm 2.82 × 10 9 t 0.53 (1 + He + /H + + 3.7He ++ /H + ) where t is the electron temperature in 10 4 K and 2.82×10 9 does the unit conversion so that S6cm is in Jy and F(Hβ) is in erg cm −2 s −1 . Using ionic helium abundances 40
Page 1 and 2: TRACING ABUNDANCES IN GALAXIES WITH
Page 3 and 4: TRACING ABUNDANCES IN GALAXIES WITH
Page 5 and 6: BIOGRAPHICAL SKETCH Shannon was bor
Page 7 and 8: ACKNOWLEDGEMENTS First and foremost
Page 9 and 10: thank my husband Ryan. The rest of
Page 11 and 12: 3 Chemical Abundances and Dust in P
Page 13 and 14: LIST OF FIGURES 1.1 Diagram of the
Page 15 and 16: ditionally we find that these nebul
Page 17 and 18: seed nuclei relative to the β deca
Page 19 and 20: shape (Carollo et al., 2007). These
Page 21 and 22: Boltzmann velocity distribution cha
Page 23 and 24: etween recapture and photoionizatio
Page 25 and 26: a whole. Additionally, abundances f
Page 27 and 28: at the appropriate temperature and
Page 29 and 30: (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: 2.4 Optical and UV Data We compleme
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 and 82: Table 3.6 Comparison of the derived
Page 83 and 84: from the most reliable line(s), and
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
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Table 3.14 Parameters of linear fit
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models that show how a binary compa
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y an outer dense O-rich torus, indi
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CHAPTER 4 ABUNDANCES IN H II REGION
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expect their abundance ratio to rem
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We extract spectra processed throug
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Figure 4.2 IRS spectra of H II regi
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IRS slits from these WIRC observati
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S IV) we employ is equal to Te(O +2
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Figure 4.3 M51 H II region Ne III/N
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Figure 4.4 shows a plot of the (Ne
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James Webb Space Telescope (JWST);
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Bernard-Salas, J. & Tielens, A. G.
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Edgar, R. G., Nordhaus, J., Blackma
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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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