Striking features in the HIFI spectrum include a rich, dense pattern of “spikes”, each representing the emission of light from a specific molecule in the Orion Nebula. This nebula is known to be one of the most prolific chemical factories in space, although the full extent of its chemistry and the pathways for molecule formation are not well understood. By sifting through the pattern of spikes in this spectrum, astronomers have identified a few common molecules that appear everywhere in the spectrum. The identification of the many other emission lines is currently ongoing.
By clearly identifying the lines associated with the more common molecules, astronomers can then begin to tease out the signature of particularly interesting molecules that are the direct precursors to life-enabling molecules. A characteristic feature of the Orion spectrum is the spectral richness: among the molecules that can be identified in this spectrum are water, carbon monoxide, formaldehyde, methanol, dimethyl ether, hydrogen cyanide, sulphur oxide, sulphur dioxide and their isotope analogues. It is expected that new organic molecules will also be identified.
“This HIFI spectrum, and the many more to come, will provide a virtual treasure trove of information regarding the overall chemical inventory and on how organics form in a region of active star formation. It harbours the promise of a deep understanding of the chemistry of space once we have the full spectral surveys available,” said Edwin Bergin of the University of Michigan principal investigator of the HEXOS Key Programme on Herschel.
The HIFI spectrum of the Orion Nebula, superimposed on a Spitzer image
of Orion. A characteristic feature is the spectral richness: among the
organic molecules identified in this spectrum are water, carbon
monoxide, formaldehyde, methanol, dimethyl ether, hydrogen cyanide,
sulphur oxide, sulphur dioxide and their isotope analogues. It is
expected that new molecules will also be identified. This spectrum is
the first glimpse at the spectral richness of regions of star and
planet formation. It harbours the promise of a deep understanding of
the chemistry of space once the complete spectral surveys are
available.
Unprecedented high resolution
HIFI was designed to provide extremely high-resolution spectra and to open new wavelength ranges for investigation, which are inaccessible to ground-based telescopes. “It is astonishing to see how well HIFI works," said Frank Helmich, HIFI principal investigator of SRON Netherlands Institute for Space Research. "We obtained this spectrum in a few hours and it already beats any other spectrum, at any other wavelength, ever taken of Orion. Organics are everywhere in this spectrum, even at the lowest levels, which hints at the fidelity of HIFI. The development of HIFI took eight years but it was really worth waiting for.”
Identification of the many spectral features visible in the Orion spectrum with transitions of particular molecular species requires sophisticated tools such as the Colgone Database of Molecular Spectroscopy (CDMS), which collect the laboratory data of several hundred moelcular species and precise line predictions. “The high spectral resolution of HIFI shows the breath-taking rechness of molecular species, which are present, despite of the hostile environment, in the stellar nurseries and sites for planet formation”, says Jürgen Stutzki, HIFI-co-principle investigator at the Universität zu Köln.
Press Release of the University of Cologne, Max Planck Institut für
Radioastronomie, Bonn, and Max Planck Institut für
Sonnensystemforschung, Lindau.
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