(Proposal ID) S17A-022

(PI) Terai, Tsuyoshi

(Proposal Title)
Deep Imaging Survey for Faint Trans-Neptunian Objects

(Abstract)
Trans-neptunian objects (TNOs) are remnants of planetesimals and their 
fragments in the outer solar system. Large objects enough to have avoided 
destructive collisions over the solar system age are likely to retain their 
primordial size distribution, while the smaller objects have collisionally 
evolved. The two populations could produce a 'break' in the size distribution. 
The break size can be a tracer for the initial total mass of TNOs and velocity 
dispersion which could be significantly excited by the planet migration. 
Comparison of the break size between dynamically 'cold' population (which 
possibly formed in-situ) and 'hot' population (which was possibly implanted 
from the inner region) provides useful insights for investigating the 
formation and evolution of TNOs. However, exact size of the break has not 
been determined yet. We here propose to perform a deep imaging observation 
at ecliptic fields using Hyper Suprime-Cam. This survey allows us to detect 
a sufficient number of small TNOs for precise measurement of the size 
distribution down to 30 km in diameter.