N+2 and CO+ in Comets 122P/1995 S1 (deVico) and C/1995 O1 (Hale–Bopp)

The End of Interstellar Chemistry as the Origin of Nitrogen in Comets and Meteorites

“…Our calculations suggest an alternative to volatile sublimation as the origin of the observed widespread depletion of N 2 in comets (Cochran, Cochran, & Barker 2000): a significant fraction of the original interstellar N 2 was destroyed before incorporation in icy cometesimals. The total population of Nbearing molecules in solid form available to the forming solar system was less than the total elemental nitrogen initially present (as N 2 ) in the protosolar core.…”

Carbon Monoxide in the Distantly Active Centaur (60558) 174P/Echeclus at 6 au

“…Other highly volatile and abundant gases, such as CO 2 , CH 4 and N 2 may contribute to distant activity, but they are difficult to observe and none have been detected in any Centaur to date. N 2 abundances can be estimated indirectly from optical spectra of N + 2 , and so far all data point to N 2 << CO in comets (Womack et al 1992, Lutz et al 1993, Cochran et al 2000, Cochran 2002, Ivanova et al 2016. Sublimation temperatures for these other volatiles are low enough that they may be expected to start sublimating if any pockets (localized solid concentrations) are sufficiently close to the surface.…”

A fluorescence model of the C3radical in comets

“…The 2DCoudé instrument is a cross-dispersed echelle spectrograph located at the f/33 coudé focus of the telescope. The exposure time was 1500 s. Data reduction has been described by Cochran et al (2000). The spectral resolution in order 85, the order with the C 3 (000-000) band, was measured using observations of a thorium arc lamp as 0.073±0.003Å (two pixels).…”