Hydrogen isocyanide in comet 73P/Schwassmann-Wachmann (fragment B)
Abstract
We present a sensitive 3 sigma upper limit of 1.1% for the HNC/HCN abundance ratio in comet 73P/SchwassmannWachmann (fragment B), obtained on 2006 May 10-11, using Caltech Submillimeter Observatory (CSO). This limit is a factor of ~7 lower than the values measured previously in moderately active comets at 1 AU from the Sun. Comet 73P/Schwassmann-Wachmann was depleted in most volatile species, except of HCN. The low HNC/HCN ratio thus argues against HNC production from polymers produced from HCN. However, thermal degradation of macromolecules, or polymers, produced from ammonia and carbon compounds, such as acetylene, methane, or ethane appears a plausible explanation for the observed variations of the HNC/HCN ratio in moderately active comets, including the very low ratio in comet 73P/Schwassmann-Wachmann reported here. Similar polymers have been invoked previously to explain anomalous N-14/N-15 ratios measured in cometary CN.
Additional Information
© 2008 American Astronomical Society. Received 2007 May 4; accepted 2007 November 28. Print publication: Issue 1 (2008 March 1). This research has been supported by NSF grant AST 05-40882 to the Caltech Submillimeter Observatory. D.C.L. acknowledges support from the Observatoire de Paris during his stay in Meudon. S.B.C. acknowledges support from NASA's Planetary Atmospheres Program. We thank N. Fray for useful discussions and the referee, M. DiSanti, for a thorough and helpful review of the manuscript.Attached Files
Published - LISapj08a.pdf
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Additional details
- Eprint ID
- 12598
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- CaltechAUTHORS:LISapj08a
- NSF
- AST 05-40882
- Observatoire de Paris
- NASA
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2009-01-12Created from EPrint's datestamp field
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2021-11-08Created from EPrint's last_modified field