2012/Nov/06

Recent Observations of Comet at Multiple Wavelengths: a Taxonomy Effort

Dr Stefanie Milam (NASA/GSFC) 

Abstract
========
Recently, there have been complimentary observations from multiple
facilities to try to unravel the chemical complexity of comets.
Incorporating results from various techniques, including: single-dish
millimeter wavelength observations, interferometers, and/or IR spectroscopy,
one can gain further insight into the abundances, production rates,
distributions, and formation mechanisms of molecules in these objects.
Such studies have provided great detail towards molecules with a-typical
chemistries, such as H2CO.  We report spectral observations of C/2007 N3
(Lulin), C/2009 R1 (McNaught), 103P/Hartley 2, and C/2009 P1 (Garradd)
with the Arizona Radio Observatory's SMT and 12-m telescopes, as well as
the NRAO Greenbank telescope and IRTF-CSHELL.  Multiple parent volatiles
(HCN, CH3OH, CO, CH4, C2H6, and H2O) as well as a number of daughter
products (CS and OH) have been detected in these objects.  We will present
a comparison of molecular abundances in these comets to those observed in
others, supporting a long-term effort of building a comet taxonomy based on
composition.  Previous work has revealed a range of abundances of parent
species (from "organics-poor" to "organics-rich") with respect to water
among comets, however the statistics are still poorly constrained and
interpretations of the observed compositional diversity are uncertain.