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arXiv · 1801.01199

Strong CO$^+$ and N$_2^+$ Emission in Comet C/2016 R2 (Pan-STARRS)

Anita L. Cochran·Adam J. McKay
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Abstract

We report on imaging and spectroscopic observations of comet C/2016~R2 (Pan-STARRS) obtained with the 0.8\,m and 2.7\,m telescopes of McDonald Observatory in November and December 2017 respectively. The comet was at a heliocentric distance greater than 3\,{\sc au} during both sets of observations. The images showed a well-developed tail with properties that suggested it was an ion tail. The spectra confirmed that we were observing well-developed bands of CO$^+$ and N$_2^+$. The N$_2^+$ detection was unequivocally cometary and was one of the strongest bands of N$_2^+$ detected in a comet spectrum. We derived the ratio of these two ions and from that we were able to derive that N$_2$/CO = 0.15. This is the highest such ratio reported for a comet. Note erratum - N2/CO=0.06 not 0.15.

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Anita L. Cochran, Adam J. McKay. 2018-01-03. Strong CO$^+$ and N$_2^+$ Emission in Comet C/2016 R2 (Pan-STARRS). https://doi.org/10.3847/2041-8213/aaab57

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