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N$_2^+$ and CO$^+$ in Comets 122P/1995 S1 (deVico) and C/1995 O1 (Hale-Bopp)

Anita L. Cochran·William D. Cochran·Edwin S. Barker
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Abstract

We observed comets 122P/1995\,S1 (deVico) and C/1995\,O1 (Hale-Bopp) with high spectral resolving power in order to determine the ratio of N$_2^+$/CO$^+$ in their comae. While we clearly detected the CO$^+$ in both of these comets, no N$_2^+$ was detected in either comet. From these spectra, we derive sensitive upper limits for N$_2^+$/CO$^+$. These upper limits are substantially below other reported detections of N$_2^+$/CO$^+$ in other comets. We discuss the prior N$_2^+$ detections and compare them with our observations. The abundance of N$_2$ in comets is important to our understanding of the condensation of ices in the solar nebula. In addition, N$_2$ is a tracer of Ar so study of N$_2$ allows an understanding of the role of comets for delivering volatiles to the terrestrial planets. It appears that many, if not most, comets are depleted in N$_2$ and it will be necessary to search for a mechanism for depleting this molecule in order to be consistent with current models of the solar nebula.

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Anita L. Cochran, William D. Cochran, Edwin S. Barker. 2000-03-08. N$_2^+$ and CO$^+$ in Comets 122P/1995 S1 (deVico) and C/1995 O1 (Hale-Bopp). https://doi.org/10.1006/icar.2000.6413

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