The Diffuse Infrared Emission of the Galaxy: The First Octant
Session 12 -- Interstellar medium
Display presentation, Monday, 9, 1995, 9:20am - 6:30pm

## [12.08] The Diffuse Infrared Emission of the Galaxy: The First Octant

David R. Ciardi (Wyoming Infrared Observatory), Ron W. Canterna (Wyoming Infrared Observatory)

We present an investigation of the spatial and temperature structure of the diffuse infrared emission in the northern half of the first quadrant of the Galaxy using the $IRAS$ data set. The diffuse infrared emission is shown to follow a csc($|b|$) law in all four $IRAS$ bands. The ratio of I$_{60\mu m}$ vs I$_{100\mu m}$ for the diffuse infrared emission is found to be $0.203 (\pm 0.001)$. The ratio of I$_{12\mu m}$ vs I$_{25\mu m}$ is $0.76 (\pm 0.01)$. The $IRAS$ flux ratios indicate average dust temperatures for the diffuse infrared emission of 25 K for the 60 $\mu$m and 100 $\mu$m bands and 200 K for the 12 $\mu$m and 25$\mu$m bands.

In addition, a deep trough has been discovered in the 12 $\mu$m band; the trough is parallel to the Galactic plane, is centered at Galactic latitude b = 40$^{\circ}$ and is approximately 10$^{\circ}$ in width. The trough also appears at 25 $\mu$m but is less pronounced. The trough is not present in the 60 $\mu$m and 100 $\mu$m bands. For the trough, the ratio of I$_{12\mu m}$ vs I$_{25\mu m}$ is $0.085 (\pm 0.02)$. The $IRAS$ flux ratios indicate average dust temperatures for the trough of 25 K for the 60 $\mu$m and 100 $\mu$m bands $but$ only 110 K for the 12 $\mu$m and 25$\mu$m bands.