Spatial Distribution of Ultraviolet Emission from Cometary Activity at 67P/Churyumov-Gerasimenko

Journal Article · Thu Jul 01 04:00:00 EDT 2021 · The Astronomical Journal (Online)

DOI:https://doi.org/10.3847/1538-3881/ABF82F· OSTI ID:23159288

Noonan, John W.; Alan Stern, S.; Keeney, Brian A.; Parker, Joel Wm.; Steffl, Andrew J.; Schindhelm, Rebecca N. ^[1]; Bockelée-Morvan, Dominique; Biver, Nicolas ^[2]; Feldman, Paul D. ^[3]; Knight, Matthew M.; Feaga, Lori M.; A’Hearn, Michael F. ^[4]; Hofstadter, Mark D.; Lee, Seungwon ^[5]; Vervack, Jr., Ronald J.; Weaver, Harold A. ^[6]; Pineau, Jon ^[7]; Medina, Richard ^[8]; Bertaux, Jean-Loup ^[9]

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1. Department of Space Studies, Southwest Research Institute, Suite 300, 1050 Walnut Street, Boulder, CO 80302 (United States)
2. LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris, 5 place Jules Janssen, F-92195 Meudon (France)
3. Department of Physics and Astronomy, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States)
4. Astronomy Department, University of Maryland, College Park, MD 20742 (United States)
5. Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)
6. Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723-6099 (United States)
7. Stellar Solutions, Inc., Palo Alto, CA 94306 (United States)
8. Department of Space Operations, Southwest Research Institute, Suite 300, 1050 Walnut Street, Boulder, CO 80302 (United States)
9. LATMOS, CNRS/UVSQ/IPSL, 11 Boulevard d’Alembert, F-78280 Guyancourt (France)

The Alice ultraviolet spectrograph on board the Rosetta orbiter provided the first near-nucleus ultraviolet observations of a cometary coma from arrival at comet 67P/Churyumov-Gerasimenko in 2014 August through 2016 September. The characterization of atomic and molecular emissions in the coma revealed the unexpected contribution of dissociative electron impact emission at large heliocentric distances and during some outbursts. This mechanism also proved useful for compositional analysis, and Alice observed many cases that suggested elevated levels of the supervolatile O{sub 2}, identifiable in part to their emissions resulting from dissociative electron impact. In this paper, we present the first two-dimensional UV maps constructed from Alice observations of atomic emission from 67P during an increase in cometary activity on 2015 November 7–8. Comparisons to observations of the background coma and an earlier collimated jet are used to describe possible changes to the near-nucleus coma and plasma. To verify the mapping method and place the Alice observations in context, comparisons to images derived from the MIRO and VIRTIS-H instruments are made. The spectra and maps we present show an increase in dissociative electron impact emission and an O{sub 2}/H{sub 2}O ratio of ~0.3 for the activity; these characteristics have been previously identified with cometary outbursts seen in Alice data. Further, UV maps following the increases in activity show the spatial extent and emission variation experienced by the near-nucleus coma, informing future UV observations of comets that lack the same spatial resolution.

• OSTI ID: 23159288
• Journal Information: The Astronomical Journal (Online), Journal Name: The Astronomical Journal (Online) Journal Issue: 1 Vol. 162; ISSN 1538-3881
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
79 ASTRONOMY AND ASTROPHYSICS
COMETS
ELECTRONS
EMISSION
MAPPING
NUCLEI
ORBITS
PLASMA
SPATIAL DISTRIBUTION
SPATIAL RESOLUTION
SPECTRA
TWO-DIMENSIONAL CALCULATIONS
ULTRAVIOLET RADIATION