Mid-IR observations of (704) Interamnia

We observe this asteroid using 8.2m Subaru telescope at mid-infrared wave bands and utilize a thermophysical model for realistic surface layers to analyze mid-infrared data from Subaru along with those of IRAS, AKARI, and Wide-field Infrared Survey Explorer (WISE)/NEOWISE.

We optimize the method to convert the WISE magnitude to thermal infrared flux with temperature-dependent color corrections, which can provide significant references for main-belt asteroids at a large heliocentric distance with low surface temperature. We derive best-fitting thermal parameters of Interamnia-a mean regolith grain size of 190_-180_^+460^{mu}m, with a roughness of 0.30_-0.17_^+0.35^ and rms slope of 27_-9_^+13^deg, thereby producing thermal inertia ranging from 9 to 92Jm^-2^s^-1/2^K^-1^ due to seasonal temperature variation.