TRACING ABUNDANCES IN GALAXIES WITH THE SPITZER ...

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3.3.3 Data Reduction We start with basic calibrated data (bcd) from the Spitzer Science Center’s pipeline version s15.3 or s16.1, and run it through the IRSCLEAN 1 program to remove rogue pixels, which uses a mask of rogue pixels from the same campaign as the data. Then we take the mean of repeated observations (cycles) to improve the signal to noise ratio. After that the background is subtracted using the off-source positions for SH and LH, and using the off-order for SL (for example, SL1 nod1 - SL2 nod1). Next we use SMART (Higdon et al., 2004) to manually extract the images, using full-slit extraction for SH and LH and variable-column extraction for SL; we also inspect the spectral profiles of each target with the Manual Source Finder tool in SMART to ensure that only one source is within the slit. Spikes due to deviant pixels which the IRSCLEAN program missed are removed manually in SMART. In order to account for flux that fell outside of the IRS slits (due either to a slight mispointing and/or the extended size of the GBPNe), we apply multiplicative scaling factors to each order and nod. The highest flux in LH sets the scaling because LH is large enough to contain the entire flux of all of our GBPNe. Thus, one nod in LH is scaled to the other, the SH nods are then scaled to LH, and the SL nods and orders are then scaled to match SH. Table 3.3 gives the scaling factors; they are usually quite small (≤1.20) except for three PNe where the scaling factors in SL (the aperture with the smallest width) reach up to 1.70. Figure 3.1 plots the scaled and nod-averaged spectra. We predict the 12 and 25 µm IRAS fluxes from these scaled IRS spectra and find generally good agreement with the actual IRAS fluxes, confirming that only the IRAS source is within the IRS slit. Finally we use the gaussian profile fitting routine in SMART to measure line fluxes for each nod position of the scaled spectra. Table 3.4 gives the observed 1 The IRSCLEAN program is available from the Spitzer Science Center’s website at http://ssc.spitzer.caltech.edu 59
nod-averaged line fluxes. Uncertainties on the line fluxes are usually ≤10%, with uncertainties greater than this marked in the table. A less-than sign in Table 3.4 indicates a 3σ upper limit obtained from the instrument resolution and the root mean square (RMS) deviation in the spectrum at the wavelength of the line. 3.4 Supplementary Data We supplement our IR data with optical and radio data from the literature to aid abundance determinations for three reasons. First, we use the observed Hβ and 6 cm radio fluxes to derive the extinction toward GBPNe. Table 3.2 gives these fluxes from the Strasbourg-ESO Catalogue of Galactic Planetary Nebula (Acker et al., 1992). Second, we adopt electron temperatures derived from ratios of optical line fluxes (discussed in §3.5.1). Third, we use optical line fluxes for ions not observable in our IR spectra (specifically lines fluxes of Ar IV, S II, O II, and O III) to reduce the need for ICFs. (As an aside, no UV line data for any of the GBPNe in our sample are available due to the large extinction toward the Bulge.) When the optical line fluxes are given as observed line fluxes, we apply the logarithmic extinction at Hβ (CHβ) given in the paper to correct the lines for extinction because it gives the correct Balmer decrement. When more than one paper gives a value for a line flux, we take the average (after correcting all line fluxes for extinction), and Table 3.5 gives the optical extinction corrected line fluxes adopted for the calculation of abundances. All of the PNe in this sample should be within ∼4 kpc or less of the Galactic Center because they were selected to be members of the Bulge. In order to de- termine approximately where they are within the Bulge to place them on a plot of abundance versus galactocentric distance, we adopt the heliocentric statistical distances from Zhang (1995). We chose these distances because Zhang (1995) lists 60
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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
Page 21 and 22: Boltzmann velocity distribution cha
Page 23 and 24: etween recapture and photoionizatio
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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
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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
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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
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Page 77 and 78: Table 3.4 Observed infrared line fl
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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
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Page 95 and 96: Figure 3.3 Profiles of PAH features
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Page 115 and 116: Figure 4.2 IRS spectra of H II regi
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Page 121 and 122: 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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