'First-of-its-kind' 3D mapping provides deeper insight into comets' chemical working
Scientists have developed detailed 3D maps of comets' atmosphere, which has provided a better insight into its chemical nature.
A NASA-led team of scientists has created detailed 3D maps of the atmospheres surrounding comets, identifying several gases and mapping their spread at the highest resolution ever achieved. Almost unheard of for comet studies, the 3-D perspective provides deeper understanding into which materials are shed from the nucleus of the comet and which are produced within the atmosphere, or coma. This helped the team nail down the sources of two key organic, or carbon-containing, molecules.
This rotating 3D map showed how HCN molecules (made of hydrogen, carbon and nitrogen) are released from the nucleus of comet Lemmon and then spread evenly throughout the atmosphere, or coma. Similar maps revealed that HNC and formaldehyde are produced in the coma, rather than the comet's nucleus.
The observations were conducted in 2013 on comets Lemmon and ISON using the Atacama Large Millimeter/submillimeter Array, or ALMA, a network of high-precision antennas in Chile. These comets are the first to be studied with ALMA.
Anthony Remijan, a scientist with the National Radio Astronomy Observatory, said that ALMA did not only help in identifying individual molecular species in the coma, but it also gave the ability to map their locations with great sensitivity.
The observations were also significant because modest comets like Lemmon and ISON contain relatively low concentrations of crucial molecules, making them difficult to probe in depth with Earth-based telescopes.
Michael Mumma, Director of the Goddard Center for Astrobiology, said that understanding organic dust was important, because such materials are more resistant to destruction during atmospheric entry, and some could have been delivered intact to early Earth, thereby fueling the emergence of life, so these observations open a new window on this poorly known component of cometary organics.
The research is published in the Astrophysical Journal Letters.
(Posted on 12-08-2014)