AAS 197, January 2001
Session 4. The Milky Way Galaxy
Display, Monday, January 8, 2001, 9:30am-7:00pm, Exhibit Hall

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[4.14] Morphology of the Milky Way's Spiral Arms

T.Y. Steiman-Cameron (Indiana U.), M.G. Wolfire (U. Maryland), D.J. Hollenbach (NASA/Ames Research Center)

We present a model for the spiral structure of the Milky Way based upon analysis of the essentially all-sky spectral line data obtained by the Cosmic Background Explorer (COBE) satellite. We conducted a reanalysis of the [C II] 128 micron and [N II] 205 micron line intensities in and near the Galactic plane. These lines are important coolants of the ISM and tracers of spiral structure. Intensity maps of these lines were derived and used to construct models for the volume emissivity of [C II] and [N II] as a function of position within the Galaxy. Emissivity models with two, three, and four arms were explored. Only a four-arm model was found to fit the COBE data. This model, with arms defined by logarithmic spiral forms, reproduces the observations extremely well.

This work was supported by NASA Grant NAG5-6773 from the NASA Astrophysics Data Program.

The author(s) of this abstract have provided an email address for comments about the abstract: tomsc@astro.indiana.edu

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