(Proposal ID) S15B-051

(PI) Kawakita, Hideyo

(Proposal Title)
The chemical compositions of comets C/2013 US10 (Catalina), C/2013 X1 (PanSTARRS) and P/2010 V1 (Ikeya-Murakami)

(Abstract)
We propose to use NIRSPEC at Keck II to measure the chemical composition of 
three comets: long-period Oort cloud comets C/2013 US10 (Catalina) (hereafter 
Catalina) and C/2013 X1 (PanSTARRS) (hereafter PanSTARRS), and P/2010 V1 
(Ikeya-Murakami) (hereafter I-M), a short-period Jupiter-family comet (JFC) of 
probable Kuiper belt origin. Determining the composition and structure of 
cometary nuclei is essential to understanding the formation and evolution of 
volatile material within our solar system. We will determine the chemical 
composition in these three comets through a sensitive search for the following 
molecular species: H_2O, CO, CH_4, CH_3OH, H_2CO, C_2H_6, HCN, C_2H_2, NH_3, 
and NH_2. Semester 2015B provides a rare opportunity because the chemical 
composition of three comets can be determined within a single night. 
Observations of all three comets offer important comparisons because the ices 
in Catalina and PanSTARRS have been subjected to less evolutionary processing 
than JFCs such as I-M. Are chemical differences seen within comets in general 
and JFCs specifically caused by evolutionary effects or formative conditions?  
Can comet chemistry and formation region be linked? Only with measurements 
such as we propose with NIRSPEC can we address these questions.