Model-Observation Comparisons Of Electron Number Densities In The Coma Of 67P/Churyumov-Gerasimenko During 2015 JanuaryShow others and affiliations
2016 (English)In: Astronomical Journal, ISSN 0004-6256, E-ISSN 1538-3881, Vol. 152, no 3, article id 59Article in journal (Refereed) Published
Abstract [en]
During 2015 January 9-11, at a heliocentric distance of similar to 2.58-2.57 au, the ESA Rosetta spacecraft resided at a cometocentric distance of similar to 28 km from the nucleus of comet 67P/Churyumov-Gerasimenko, sweeping the terminator at northern latitudes of 43 degrees N-58 degrees N. Measurements by the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis/Comet Pressure Sensor (ROSINA/COPS) provided neutral number densities. We have computed modeled electron number densities using the neutral number densities as input into a Field Free Chemistry Free model, assuming H2O dominance and ion-electron pair formation by photoionization only. A good agreement (typically within 25%) is found between the modeled electron number densities and those observed from measurements by the Mutual Impedance Probe (RPC/MIP) and the Langmuir Probe (RPC/LAP), both being subsystems of the Rosetta Plasma Consortium. This indicates that ions along the nucleus-spacecraft line were strongly coupled to the neutrals, moving radially outward with about the same speed. Such a statement, we propose, can be further tested by observations of H3O+/H2O+ number density ratios and associated comparisons with model results.
Place, publisher, year, edition, pages
2016. Vol. 152, no 3, article id 59
Keyword [en]
comets: individual (67P), molecular processes
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
URN: urn:nbn:se:uu:diva-305483DOI: 10.3847/0004-6256/152/3/59ISI: 000383804300007OAI: oai:DiVA.org:uu-305483DiVA, id: diva2:1038515
Funder
Swedish National Space Board, 109/02 114/13 135/13 166/14Swedish Research Council, 621-2013-4191 621-2014-5526
Note
Correction in: Astronomical journal, Volume: 153, Issue: 1, Article Number: 50
DOI: 10.3847/0004-6256/153/1/50
2016-10-182016-10-182017-11-14Bibliographically approved