Thursday September 5th, 2013

The first author can only be trusted so far. For one, Section 2.3 fails to mention a certain contributing grad student that helped with the NGC628 IRS data. For another, he’s short and his hair is too awesome.

He’s dead to me.
</joke>

Our very own Kevin Croxall tackles the annoying issues surrounding chemical abundances using NGC628. This is certainly worth your time!

Towards A Removal of Temperature Dependencies from Abundance Determinations

Kevin V. Croxall, J.D. Smith, B.R. Brandl, B. A. Groves, R. C. Kennicutt, K. Kreckel, B. D. Johnson, E. Pellegrini, K. M. Sandstrom, F. Walter, L. Armus, P. Beirao, D. Calzetti,D.A. Dale, M. Galametz, J. L. Hinz, L. K. Hunt, J. Koda, E. Schinnerer
(Submitted on 3 Sep 2013)

The metal content of a galaxy is a key property for distinguishing between viable galaxy evolutionary scenarios, and it strongly influences many of the physical processes in the interstellar medium. An absolute and robust determination of extragalactic metallicities is essential in constraining models of chemical enrichment and chemical evolution, however, current gas phase abundance determinations from optical fine-structure lines are uncertain to 0.8 dex as conversion of these optical line fluxes to abundances is strongly dependent on the electron temperature of the ionized gas. In contrast, the far-IR emission lines can be used to derive an O++ abundance that is relatively insensitive to temperature, while the ratio of the optical to far-IR lines provides a consistent temperature to be used in the derivation of an O$^+$ abundance. We present observations of the [O III] 88 \micron\ fine-structure line in NGC 628 that were obtained as part of the KINGFISH program. These data are combined with optical IFU data to derive oxygen abundances for seven HII regions. We find the abundance of these regions to all lie between the high and low values of strong line calibrations and in agreement with estimates that assume temperature fluctuations are present in the HII regions.

Comments: 12 pages, 7 Figures, 3 Tables, 6 online-only figures, accepted for publication in ApJ
Subjects: Cosmology and Extragalactic Astrophysics (astro-ph.CO)
Cite as: arXiv:1309.0817 [astro-ph.CO]
(or arXiv:1309.0817v1 [astro-ph.CO] for this version)
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