Multi-band photometry of trans-Neptunian objects in the Subaru Hyper Suprime-Cam survey

摘要

We present visible multi-band photometry of trans-Neptunian objects (TNOs) observed by the Subaru Telescope in the framework of the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) from 2014 March to 2016 September. We measured the five broad-band (g, r, i, z, and Y) colors over the wavelength range from 0.4?μm to 1.0?μm for 30 known TNOs using the HSC-SSP survey data covering ～500?deg2 of sky within ±30° of ecliptic latitude. This dataset allows us to investigate the correlations between the dynamical classes and visible reflectance spectra of TNOs. Our results show that the hot classical and scattered populations with orbital inclination (I) of I???6° share similar color distributions, while the cold classical population with I???6° has a different color distribution from the others. The low-I population has reflectance increasing toward longer wavelengths up to ～0.8?μm, with a steeper slope than the high-I population at ??0.6?μm. We also find a significant anti-correlation between g???r/r???i colors and inclination in the high-I population, as well as a possible bimodality in the g???i color vs. eccentricity plot.