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Changes in the Physical Environment of the Inner Coma of 67P/Churyumov–Gerasimenko with Decreasing Heliocentric Distance

Bodewits, D.; Lara, L. M.; A’Hearn, M. F.; La Forgia, F.; Gicquel, A.; Kovacs, G.; Knollenberg, J.; Lazzarin, M.; Lin (林忠義), Z.-Y.; Shi, X.; Snodgrass, C.; Tubiana, C.; Sierks, H.; Barbieri, C.; Lamy, P. L.; Rodrigo, R.; Koschny, D.; Rickman, H.; Keller, H. U.; Barucci, M. A.; Bertaux, J.-L.; Bertini, I.; Boudreault, S.; Cremonese, G.; Da Deppo, V.; Davidsson, B.; Debei, S.; De Cecco, M.; Fornasier, S.; Fulle, M.; Groussin, O.; Gutiérrez, P. J.; Güttler, C.; Hviid, S. F.; Ip, W.-H.; Jorda, L.; Kramm, J.-R.; Kührt, E.; Küppers, M.; López-Moreno, J. J.; Marzari, F.; Naletto, G.; Oklay, N.; Thomas, N.; Toth, I. and Vincent, J.-B. (2016). Changes in the Physical Environment of the Inner Coma of 67P/Churyumov–Gerasimenko with Decreasing Heliocentric Distance. Astronomical Journal, 152(5), article no. 130.

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The Wide Angle Camera of the OSIRIS instrument on board the Rosetta spacecraft is equipped with several narrow-band filters that are centered on the emission lines and bands of various fragment species. These are used to determine the evolution of the production and spatial distribution of the gas in the inner coma of comet 67P with time and heliocentric distance, here between 2.6 and 1.3 au pre-perihelion. Our observations indicate that the emission observed in the OH, O I, CN, NH, and NH2 filters is mostly produced by dissociative electron impact excitation of different parent species. We conclude that CO2 rather than H2O is a significant source of the [O I] 630 nm emission. A strong plume-like feature observed in the CN and O I filters is present throughout our observations. This plume is not present in OH emission and indicates a local enhancement of the CO2/H2O ratio by as much as a factor of 3. We observed a sudden decrease in intensity levels after 2015 March, which we attribute to decreased electron temperatures in the first few kilometers above the surface of the nucleus.

Item Type: Journal Item
Copyright Holders: 2016 The American Astronomical Society
ISSN: 1538-3881
Keywords: atomic processes; comets: individual (67P/Churyumov–Gerasimenko); molecular processes; plasmas; radiation mechanisms: non-thermal; techniques: image processing
Academic Unit/School: Faculty of Science, Technology, Engineering and Mathematics (STEM) > Physical Sciences
Faculty of Science, Technology, Engineering and Mathematics (STEM)
Research Group: Space
Item ID: 48360
Depositing User: Colin Snodgrass
Date Deposited: 15 Feb 2017 14:57
Last Modified: 18 Jun 2020 03:41
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