Collaborative Research: Elucidating the Composition of our Solar System's Most Primitive Materials - Comprehensive Chemical Analysis of a Halley-Type Comet

About This Grant

Radio/submillimeter spectroscopy is a sensitive probe of the gases present in cometary atmospheres (comae), including molecules not readily detected at other wavelengths. Such observations provide a unique window into the composition of our planet-forming disk. This collaborative research project will focus on analyzing observations of the Halley-type comet 12P/Pons-Brooks (one of the most active comets of the last decade), using the Atacama Large Millimeter/submillimeter Array (ALMA). The resulting data will represent a major advance in sensitivity and molecular coverage, including spectral/spatial maps of at least 26 different molecules. The project will provide postdoctoral training in cometary science and astrochemical modeling, with an emphasis on support for postdoc professional development and scientific growth. The project will take advantage of the unrivaled sensitivity and resolution of ALMA data, implementing updated radiative transfer models to produce: (1) nucleus (and coma) mixing ratios and production scale lengths for > 26 different molecular species; (2) spatial maps for multiple gases, including organic molecules, S-bearing species and molecules of possible pre-biotic relevance; (3) isotopic ratios in key cosmogonic indicators (D/H, 14N/15N) to probe the history of cometary matter; (4) coma physical properties, including temperature, density, velocity structure and jet morphologies, to test our understanding of cometary outflows. Coma gas sources and extended spatial distributions will be analyzed using numerical (hydrodynamic) models incorporating gas-phase photochemistry and icy grain sublimation. Establishing the inventory of molecules in cometary ices will provide improved constraints on initial conditions for origin-of-life studies. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.