Combining for the first time a blind, algorithm driven analytic approach with authentic PAH spectra, members of the Astrophysics & Astrochemistry Laboratory are now able to systematically track parts of carbon’s molecular evolution across the Universe. On Tuesday, May 24th, 2013, simultaneous with the appearance of a paper in The Astrophysical Journal describing their work, NASA Ames issued a press release. The team’s work successfully demonstrates a powerful new tool that will change the way data are analyzed from current and future NASA missions such as SOFIA and JWST.
Analyzing mid-infrared spectral maps obtained by the Spitzer Space Telescope of the celestial object in the constellation of Cepheus named the Iris Nebula, also known as NGC 7023, the emission attributed to polycyclic aromatic hydrocarbons (PAHs) could be dissected. The NASA Ames PAH IR Spectroscopic Database, a unique collection of over 700 experimentally measured and computed PAH spectra has been key in their analyzes (www.astrochem.org/pahdb). Making use of a blind, algorithmic driven approach and incorporating an appropriate astrophysical emission model, the PAH emission could be assigned to different PAH subclasses, namely, 1) charge, 2) size, 3) composition and 4) structure. Emission maps of the region created for each of these subclasses paint a coherent astrophysical picture. Irregular, small, neutral PAHs become important when moving into more benign regions away from the hot star, whilst the regular, large, charged PAHs are losing their peripheral hydrogens closer to the hot star, where also spectral signatures of Buckyballs appear. Nitrogenated PAHs (PANHs), commonly associated with prebiotic molecules, i.e., precursors to life, appear consistently in their results and might have far reaching implications.
More information can be found at www.astrochem.org/pahdb/iris.
This work was supported by NASA’s Carbon in the Galaxy Consortium under the auspices of the Astrophysics Research and Analysis Program.