Infrared Properties of the Halo, Bulge and Disk of the Edge-on Galaxy NGC 7814.

2MASS and Spitzer images of the edge-on galaxy NGC 7814 were used to extract the morphologies and spectral energy distributions (SEDs) of the disk, bulge and halo components of this galaxy from 1.25 to 24 μm. This represents the first direct determination of the mid-infrared emission of the bulge and halo components of a galaxy other than the Milky Way. The SEDs of all three structures imply the presence of emission components from direct stellar light and from at least one further component. For the disk, this is interpreted as dust emission having properties typical of star forming disks. The very significant excess emission from the bulge and the halo has an unknown origin. We discuss potential explanations such as dust emission in an interstellar medium, galactic winds, star forming regions and circumstellar dust, as well as emission from brown dwarfs. [ABSTRACT FROM AUTHOR]