Laboratory study of ammonia indices of refraction with water ice
Abstract
A prominent, ammonia-linked absorption band at 2.2 µm was observed by New Horizons in the spectrum of Pluto's moons Charon, Hydra, and Nix. This absorption band or its suspected presence was also reported on a number of TNOs. Detectable ammonia on these bodies is surprising since radiation is expected to destroy this molecule on relatively short timescales. This might indicate that some kind of resurfacing process is replenishing the surface ammonia even on bodies such as Hydra and Nix that are too small to support cryovolcanism. At present, analysis of the 2.2 µm band has been hampered by a lack of complex index of refraction data on ammonia and its associated hydrates. Here we report on a combined project of laboratory experimental measurements and theoretical quantum chemistry to determine the complex indices of refraction of amorphous ammonia, cubic crystalline ammonia, and ammonia hydrates for improved modeling of the 2.2 µm band in outer Solar System environments. This data should prove to be especially useful if ammonia or ammoniated species are also discovered on the New Horizons close encounter target (486958) 2014 MU69 in 2019.
- Publication:
-
AAS/Division for Planetary Sciences Meeting Abstracts #50
- Pub Date:
- October 2018
- Bibcode:
- 2018DPS....5050603R