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Unusually high CO abundance of the first active interstellar comet
Status report
From: arXiv.org e-Print archive
Posted: Wednesday April 22, 2020
Cordiner, MA, Milam, SN, Biver, N., Bockelée-Morvan, D., Roth, NX, Bergin, EA, Jehin, E., Remijan, AJ, Charnley, SB, Mumma, MJ, Boissier, J., Crovisier, J., Paganini, L., Kuan, Y.-J., Lis, D. C
Comets spend most of their lives at great distances from any star, during which time their interior compositions remain relatively unchanged. Therefore, cometary observations can provide a direct insight into the chemistry that occurred during its birth at the time of the planet’s formation. To date, there have been no confirmed observations of parental volatiles (gases released directly from the nucleus) of a comet from any planetary system other than our own. Here we present high-resolution interferometric observations of 2I / Borisov, the first confirmed interstellar comet, obtained using the Atacama Large Millimeter / submillimeter Array (ALMA) from December 15 to 16, 2019. Our observations reveal the emission of hydrogen cyanide (HCN ), and carbon monoxide (CO), coinciding with the expected position of 2I / Borisov nucleus, with production rates Q (HCN) = (7.0 ± 1.1) × 1023 s – 1 and Q (CO) = (4.4 ± 0.7) × 1026 s −1. While the abundance of HCN relative to water (0.06-0.16%) seems similar to that of typical comets, previously observed in our Solar System, the abundance of CO (35-105%) is among the highest observed on any kite within 2 ~ au of the sun. This shows that 2I / Borisov must have formed in a relatively CO-rich environment, probably beyond the CO ice line in the very cold outer regions of a distant protoplanetary accretion disk, as part of a small-body population and ice creams analogous to Proto-Kuiper Belt of our Solar System.
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
DOI: 10.1038 / s41550-020-1087-2
Quote as: arXiv: 2004.09586 [astro-ph.EP] (or arXiv: 2004.09586v1 [astro-ph.EP] for this version)
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From: Martin Cordiner PhD [view email] [v1] Mon, April 20, 2020 19:28:30 UTC (562 KB)
https://arxiv.org/abs/2004.09586
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