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/Schwassmann-Wachmann (Fragment B), obtained on May 10-11, 2006 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 14N/15N ratios measured in cometary CN.

6 pages, 5 figures, 2 tables

References in corpus (1)

• Biomolecules in the Interstellar Medium and Comets

Cited by in corpus (19)

• Mapping the release of volatiles in the inner comae of comets C/2012 F6 (Lemmon) and C/2012 S1 (ISON) using the Atacama Large Millimeter/Submillimeter Array
• The chemical diversity of comets
• Radio observations of Jupiter-family comets
• Molecular observations of comets C/2012 S1 (ISON) and C/2013 R1 (Lovejoy): HNC/HCN ratios and upper limits to PH3
• Molecular composition of comet 46P/Wirtanen from millimetre-wave spectroscopy
• Molecular investigations of comets C/2002 X5 (Kudo-Fujikawa), C/2002 V1 (NEAT), and C/2006 P1 (McNaught) at small heliocentric distances
• Infrared Spectroscopy of Comet 73P/Schwassmann-Wachmann 3 using the Spitzer Space Telescope
• ALMA mapping of rapid gas and dust variations in comet C/2012 S1 (ISON): new insights into the origin of cometary HNC
• Gas Sources from the Coma and Nucleus of Comet 46P/Wirtanen Observed Using ALMA
• No compelling evidence of distributed production of CO in comet C/1995 O1 (Hale-Bopp) from millimeter interferometric data and a reanalysis of near-IR lines
• A survey of volatile species in Oort cloud comets C/2001 Q4 (NEAT) and C/2002 T7 (LINEAR) at millimeter wavelengths
• Emission from HCN and CH${}_3$OH in comets. Onsala 20-m observations and radiative transfer modelling
• Associative detachment (AD) paths for H and CN- in the gas-phase: astrophysical implications
• Neutral-Neutral Synthesis of Organic Molecules in Cometary Comae
• Formation of anionic C,N-bearing chains in the Interstellar medium via reactions of H${}^{-}$ with HC${}_x$N for odd-valued x from 1 to 7
• Exploring the volatile composition of comets C/2012 F6 (Lemmon) and C/2012 S1 (ISON) with ALMA
• Submillimetric spectroscopic observations of volatiles in comet C/2004 Q2 (Machholz)
• Evidence of ammonium salts in comet 67P as explanation for the nitrogen depletion in cometary comae
• Leveraging the ALMA Atacama Compact Array for Cometary Science: An Interferometric Survey of Comet C/2015 ER61 (PanSTARRS) and Evidence for a Distributed Source of Carbon Monosulfide