NEAR-INFRARED AND FAR-INFRARED OBSERVATIONS OF INTERPLANETARY DUST BANDS FROM THE COBE DIFFUSE INFRARED BACKGROUND EXPERIMENT

Data from the Diffuse Infrared Background Experiment (DIRBE) instrumen t aboard the COBE spacecraft have been used to examine the near and fa r infrared signatures of the interplanetary dust (IPD) bands. Images o f the dust band pairs at ecliptic latitudes of +/- 1.4 degrees and +/- 10 degrees have been produced at DIRBE wavelengths from 1.25 to 100 m u m. The observations at the shorter wavelengths provide the first evi dence of scattered sunlight from particles responsible for the dust ba nds. It is found that the grains in the bands and those in the smooth IPD cloud have similar spectral energy distributions, suggesting simil ar compositions and possibly a common origin. The scattering albedos f rom 1.25 to 3.5 mu m for the grains in the dust bands and those in the smooth IPD cloud are 0.22 and 0.29, respectively. The 10 degrees band pair is cooler (185 +/- 10 K) than the smooth interplanetary dust clo ud (259 +/- 10 K). From both parallactic and thermal analyses, the imp lied location of the grains responsible for the peak brightness of the 10 degrees band pair is 2.1 +/- 0.1 AU from the Sun. A parallactic di stance of 1.4 +/- 0.2 AU is found for the peak of the 1.4 degrees band pair.