Formation of the Outer Solar System: an Icy Legacy (FOSSIL)

Chan-Kao Chang^1*, Ying-Tung Chen¹, Shiang-Yu Wang¹, Matthew Lehner¹

¹Institute of Astronomy and Astrophysics, Academia Sinica, Taiwan

* Presenter:Chan-Kao Chang, email:rex@astro.ncu.edu.tw

FOSSIL is a large survey of the outer solar system to discover and characterize distant small bodies. With the combination of the Hyper SuprimeCam with the Subaru telescope, FOSSIL will be able to detect and characterize small/distant bodies including Trans-Neptunian Objects (TNOs), Centaurs, Trojans, main belt asteroids. The targeted exposure depth is 25.6 in r band which is around 1 magnitude deeper than the coming Vera C. Rubin Observatory Survey. The survey team includes scientists from Canada, China, India, Japan, Korea, Taiwan and US, while the team in ASIAA is leading for most of the survey planning, observation and data reduction efforts.

The whole FOSSIL survey is separated into two phases to accommodate better conditions to detect Jovian Trojans and schedule constraints of the Subaru telescope. The FOSSIL I observation targets mainly on Jovian Trojans (JTs) and main belt asteroids (MBAs) was carried out in 2020 and early 2021. The second phase of FOSSIL aims to detect, track high q and resonant TNOs to reveal the details of the Neptune migration process. The proposal for FOSSIL II was submitted and reviewed recently.

In this presentation, we will cover the new results of the FOSSIL I observations including the lightcurve analysis for MBAs, JTs, Hildas, and TNOs and the size distribution of JTs. We will also explain the future plan for the FOSSIL II.

Keywords: Small Solar System Bodies, Wide-Field Surveys, Lightcurve