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Home > News and Updates > Two New Molecules Detected with SOFIA


Two New Molecules Detected with SOFIA

Observations with the airborne observatory help to understand
both sulfur and water chemistry in the interstellar medium

Images below

October 25, 2012

Scientific results from observations made in 2011 from NASA’s Stratospheric Observatory for Infrared Astronomy, SOFIA, show the first detection in the interstellar medium of two molecules, the mercapto radical SH and the deuterated hydroxyl radical OD. SH is important for the investigation of sulfur chemistry in the interstellar medium, and OD, a version of hydroxyl (OH) with the hydrogen atom replaced by a heavier deuterium atom, plays a corresponding role in understanding the chemical pathways for formation of water in the universe. Both molecules show transition lines in the terahertz regime of the electromagnetic spectrum that cannot be observed from ground-based telescopes.

The detection and investigation of interstellar molecules is one of the strong suits of the German Receiver for Astronomy at Terahertz Frequencies, or GREAT, spectrometer. GREAT has been developed by a consortium of German research institutes led by Rolf Guesten of the Max Planck Institute for Radio Astronomy. These results were published in the May 2012 special issue of the European journal Astronomy & Astrophysics Letters (GREAT: early science results, A&A 542, F1).

SOFIA is a partnership of NASA and the German Aerospace Center (DLR).  NASA’s Dryden Flight Research Center (Edwards, Calif.) manages the SOFIA program. NASA's Ames Research Center (Moffett Field, Calif.) manages SOFIA’s science mission in cooperation with the Universities Space Research Association (USRA; Columbia, Md.) and the German SOFIA Institute (DSI; Stuttgart). SOFIA is based at NASA’s Dryden Aircraft Operations Facility (DAOF) in Palmdale, Calif.

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Link to the Max Planck Institute's version of this feature story (in German):

Rho Oph

Infrared image of the Rho Ophiuchi star formation region, about 400 light-years from Earth, showing dense, dark filamentary clouds of gas and dust. The position of the optically obscured low-mass protostar IRAS 16293-2422 towards which the OD molecule has been detected is marked with a white circle and arrow at the left. (NASA/JPL-Caltech/WISE Team)

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OD Spectrum

A spectral absorption line of the OD molecule (deuterated hydroxyl radical) is seen in the center of this plot at a frequency of 1391.5 gigahertz (wavelength 215 microns). This molecule is an important marker of the formation of interstellar water and may be used as a chemical clock for the first stages of the star formation process. (MPIfR/B. Parise et al. 2012, A&A 542, L5)

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Galactic Plane  

Radio image of the Milky Way galactic plane. The W49 interstellar cloud complex is the bright radio source labeled at a galactic longitude of about 43 degrees, in the direction of the "summer triangle" constellation Aquila. W49 is a region of massive star formation in our galaxy at a distance of approximately 37,000 light years, completely obscured by interstellar dust at visual wavelengths. W49N, the target of the SOFIA/GREAT investigation, is the northern part of W49. (MPIfR/W. Reich)

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SH spectrum  

Two spectral lines of the SH molecule (mercapto radical), indicated by arrows, are detected in absorption towards W49N at frequencies of about 1382.7 and 1383.1 gigahertz (wavelength 217 microns), along with lines of other gas constituent along the line of sight and within W49N. SH is important for the investigation of sulfur chemistry in the interstellar medium. (D. Neufeld et al. 2012, A&A 542, L6)

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