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R. Drimmel (Astronomical Observatory of Turin), D. Spergel (Princeton Observatory)
Using far-infrared (FIR) and near-infrared (NIR) data from the COBE/DIRBE instrument for Galactic latitudes |b| < 30 degrees, we model the stellar and dust distribution in the Galactic plane. Making the assumption that the Galaxy is transparent in the 240 \mu FIR waveband, the dust emission can be modeled using the following components: a warped exponential disk with scale length 0.30 R\odot and scale height 0.017 R\odot, an spiral arm component, and a feature coinciding with the local (Orion) arm that produces prominent emission features at l = 80 and -100 degrees. The dust distribution is used to calculate absorbtion at the NIR J and K wavebands, while stellar emission in these wavebands is modeled with two components: a warped exponential disk with a scale length of 0.27 R\odot and scale height of 0.029 R\odot, and from a spiral arm component. The warp is evident in both the dust and stellar component, and starts within the Solar Circle. In the FIR (dust) emission, the spiral arms are well described by their mapping with the HII regions, which shows four arms, whereas in the NIR the (stellar) emission can be well described by a {\em two-armed} logarithmic spiral with a pitch angle of 13.7 degrees.
The author(s) of this abstract have provided an email address for comments about the abstract: drimmel@to.astro.it