Comet outbursts and polymers of HCN

The compositional evolution of C/2012 S1 (ISON) from ground-based high-resolution infrared spectroscopy as part of a worldwide observing campaign

“…Hydrogen atom addition reactions can readily deplete HCN on grains (Theule et al, 2011;Bast et al, 2013), as can polymerization initiated by reactions with free radicals (e.g. Rettig et al, 1992). Therefore, the increasing HCN/H 2 O in ISON as it approached perihelion may be further evidence for a transition from sampling processed outer layers to sampling increasingly more primitive natal material that was formerly protected from alteration deep within the nucleus.…”

The search for a cometary outbursts mechanism: a comparison of various theories

“…Using the data concerning the polymers existence within the comets Rettig et al (1992) suggested that the cometary outbursts are possible due to polymerization of the HCN.…”

“…According to Rettig et al (1992) polymerization can be started at least in two ways. The first one is due to an accidental absorption of UV photons by fresh exposed undersurface layers of a cometary nucleus rich in HCN molecules.…”

“…It must be emphasized also that the reaction of the polymerization of HCN can potentially trigger an outburst of a comet without any transformation of amorphous water ice. Assuming 1% concentration of HCN (Rettig et al 1992), it can be simply shown that if the amount of cometary matter which undergoes polymerization, varies between 0.54 · 10 7 kg and 0.54·10 9 kg, then the released energy varies between 10 12 J and 10 14 J. On the other hand, these values of mass and energy, released by the nucleus are typical for cometary outbursts.…”

“…Many researchers have tried to explain this phenomenon by various mechanisms and sources. (Patashnik et al 1974;Smoluchowski 1981;Hughes 1991a;Intrilligator & Dreyer 1991;Rettig et al 1992;Prialnik & Bar-Nun 1992;Toth 2001). Nevertheless, none of these hypotheses has been finally confirmed and accepted.…”