TRACING ABUNDANCES IN GALAXIES WITH THE SPITZER ...

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3.3 Spitzer IRS Data 3.3.1 Observations We observed eleven GBPNe with the Spitzer IRS between September 2006 and September 2007 as part of the Guaranteed Time Observation program 30550. In order to minimize slit losses, PeakUp with 0.4 ′′ positional accuracy was performed for the six PNe where it was possible, while blind pointing with ∼1 ′′ positional accuracy was done for the remaining five PNe. We observed these PNe with the IRS Short-Low (SL), Short-High (SH), and Long-High (LH) modules, covering the wavelength range from 5 to 40 µm. In order to subtract the background and minimize the effect of rogue pixels, we took off-source observations for SH and LH; for the SL module we subtracted the background by differencing the orders. The data were taken in staring mode so that spectra were obtained at two nod positions along each IRS slit. For SH and LH, a short exposure time of six seconds was used to keep the bright lines from saturating, with a total of four cycles for redundancy and to aid in the removal of cosmic rays; for the SL module, data were taken in three cycles of fourteen seconds each. Table 3.1 gives the object names, their Astronomical Observation Request (AOR) keys and coordinates. 3.3.2 Source Selection The sources were selected to ensure they belong to the Bulge according to the following criteria. (1) Foremost, the best criterion for ensuring Bulge membership is having galactic coordinates |ℓ| < 10 ◦ and |b| < 10 ◦ (Pottasch & Beintema, 1999). All of the sources were selected to meet this criterion. (2) We selected objects with high radial velocities, except for two objects, PNG001.6-01.3 and PNG002.1+03.3, where they are unknown and whose IRAS fluxes and positions indicate that they 55
are members of the Bulge, (Acker et al., 1992). (3) Finally, the objects have diameters � 5 ′′ . Pottasch & Beintema (1999) consider all PNe with diameters > 12 ′′ to be foreground objects, and thus choosing small diameters helped to ensure Bulge membership. Table 3.2 gives the radial velocities and diameters of our GBPNe. Additionally, in order to make certain that we could get good Spitzer IRS spectra of the GBPNe, we chose isolated objects in the IRAS Point Source Catalog (PSC) with small radial extent, accurate coordinates, and observable intensities. While the IRAS PSC is not as sensitive as our Spitzer observations (the IRAS PSC catalog is sensitive to a couple hundred mJy whereas our Spitzer observations are sensitive to a few mJy), we check that only one source is on the slit during the data reduction. The criterion of selecting PNe with small sizes also ensured that nearly all of the flux from most of the PNe could be observed within SL, the smallest IRS slit at 3.6 ′′ across. The sources also were chosen to have coordinates known to better than 1.4 ′′ from the radio positions of Condon & Kaplan (1998), and these coordinates were refined with the 2MASS catalog. Finally, we chose objects with radio fluxes at 21 cm (F21cm) that implied IR fluxes bright enough (F21cm > 10 mJy) to allow for short integration times, but dim enough (F21cm < 50 mJy) to not saturate any of the IRS modules. Table 3.2 gives the IRAS fluxes at 12 and 25 µm as well as the radio fluxes at 21 cm for our objects. 56
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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
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 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: essential data on important ionizat
Page 71 and 72: Table 3.2 Properties of observed GB
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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
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Page 93 and 94: Figure 3.2 Continuum subtracted spe
Page 95 and 96: Figure 3.3 Profiles of PAH features
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Page 101 and 102: towards the Galactic Center. On the
Page 103 and 104: Table 3.14 Parameters of linear fit
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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
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Page 115 and 116: Figure 4.2 IRS spectra of H II regi
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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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