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On the ubiquity of ...
On the ubiquity of molecular anions in the dense interstellar medium
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- Cordiner, M. A. (författare)
- NASA Goddard Space Flight Center,Catholic University of America
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- Buckle, J. V. (författare)
- University Of Cambridge
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- Wirström, Eva, 1977 (författare)
- Chalmers tekniska högskola,Chalmers University of Technology,NASA Goddard Space Flight Center
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- Olofsson, Henrik, 1972 (författare)
- Chalmers tekniska högskola,Chalmers University of Technology
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- Charnley, S. B. (författare)
- NASA Goddard Space Flight Center
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(creator_code:org_t)
- 2013-05-23
- 2013
- Engelska.
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 770:1
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https://doi.org/10.1...
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Abstract
Ämnesord
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- Results are presented from a survey for molecular anions in seven nearby Galactic star-forming cores and molecular clouds. The hydrocarbon anion C6H- is detected in all seven target sources, including four sources where no anions have been previously detected: L1172, L1389, L1495B, and TMC-1C. The C6H-/C6H column density ratio is greater than or similar to 1.0% in every source, with a mean value of 3.0% (and standard deviation 0.92%). Combined with previous detections, our results show that anions are ubiquitous in dense clouds wherever C6H is present. The C6H-/C6H ratio is found to show a positive correlation with molecular hydrogen number density, and with the apparent age of the cloud. We also report the first detection of C4H- in TMC-1 (at 4.8 sigma confidence), and derive an anion-to-neutral ratio C4H-/C4H = (1.2 +/- 0.4) x 10(-5)(= 0.0012% +/- 0.0004%). Such a low value compared with C6H- highlights the need for a revised radiative electron attachment rate for C4H. Chemical model calculations show that the observed C4H- could be produced as a result of reactions of oxygen atoms with C5H- and C6H-.
Ämnesord
- NATURVETENSKAP -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)
Nyckelord
- ISM: clouds
- ISM: molecules
- astrochemistry
- stars: formation
- ISM: abundances
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- ref (ämneskategori)
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