NIR albedos of main-belt asteroids

These fits are derived from reflected-light near-infrared images taken simultaneously with thermal emission measurements, allowing for more accurate measurements of the near-infrared albedos than is possible for visible albedo measurements. Because our sample requires reflected light measurements, it undersamples small, low-albedo asteroids, as well as those with blue spectral slopes across the wavelengths investigated.

We find that the main belt separates into three distinct groups of 6%, 16%, and 40% reflectance at 3.4 {mu}m. Conversely, the 4.6 {mu}m albedo distribution spans the full range of possible values with no clear grouping. Asteroid families show a narrow distribution of 3.4 {mu}m albedos within each family that map to one of the three observed groupings, with the (221) Eos family being the sole family associated with the 16% reflectance 3.4 {mu}m albedo group.