Ionic emissions in comet C/2016 R2 (Pan-STARRS)

Abstract

We carried out observations of a peculiar comet, C/2016 R2 (Pan-STARRS), using a low resolution spectrograph mounted on the 1.2m telescope at Mount Abu Infrared Observatory, India. The comet was observed on two dates in January 2018, when it was at a heliocentric distance of 2.8 AU. Study based on our observations revealed that the optical spectrum of this comet is quite unusual as compared to general cometary spectra. Most of the major cometary emissions like C${}_2$, C${}_3$ and CN were absent in comet C/2016 R2. However, the comet spectrum showed very strong emission bands from ionic species like CO${}^{+}$ and N${}_2^{+}$. A mean N${}_2$/CO ratio of 0.09 $\pm$ 0.02 was derived from the spectra and an extremely low depletion factor of 1.6 $\pm$ 0.4 has been estimated for this ratio as compared to the solar nebula. We have also detected minor emission features beyond 5400 Angstroms, albeit marginally. The column densities of CO${}^{+}$ and N${}_2^{+}$ were calculated from their emission bands. The optical spectrum suggests that the cometary ice is dominated by CO. The low depletion factor of N${}_2$/CO ratio in this comet, as compared to the solar nebula and the unusual spectrum of the comet are consequences of distinctive processing at the location of its formation in the early solar nebula.

Accepted for Publication in MNRAS

References in corpus (17)

• Oort Cloud and Scattered Disc formation during a late dynamical instability in the Solar System
• The Formation of the Oort Cloud in Open Cluster Environments
• A High Spectral Resolution Atlas of Comet 122P/de Vico
• 2I/Borisov: A C${}_2$ depleted interstellar comet
• The Peculiar Volatile Composition of CO-Dominated Comet C/2016 R2 (PanSTARRS)
• N${}_2^{+}$ and CO${}^{+}$ in Comets 122P/1995 S1 (deVico) and C/1995 O1 (Hale-Bopp)
• Volatile inventories in clathrate hydrates formed in the primordial nebula
• The extraordinary composition of the "blue comet" C/2016 R2 (PanSTARRS)
• Direct evidence of multiple reservoirs of volatile nitrogen in a protosolar nebula analogue
• A protosolar nebula origin for the ices agglomerated by Comet 67P/Churyumov-Gerasimenko
• A Search for N2+ in Spectra of Comet C/2002C1 (Ikeya-Zhang)
• High resolution optical spectroscopy of the ${\mathrm{N}}_2$-rich comet C/2016 R2 (PanSTARRS)
• Strong CO${}^{+}$ and N${}_2^{+}$ Emission in Comet C/2016 R2 (Pan-STARRS)
• Carbon Chain Depletion of 2I/Borisov
• C/2016 R2 (PANSTARRS): A comet rich in CO and depleted in HCN
• Capture of interstellar objects: a source of long-period comets
• Optical Spectroscopy of Comet C/2014 Q2 (Lovejoy) from MIRO

Cited by in corpus (3)

• Knowledge Gaps in the Cometary Spectra of Oxygen-Bearing Molecular Cations
• A physico-chemical model to study the ion densitydistribution in the inner coma of comet C/2016 R2(Pan-STARRS)
• Ionic emissions and activity evolution in comet C/2020 F3 (NEOWISE): Insights from long-slit spectroscopy and photometry