Effective ion speeds at similar to 200-250 km from comet 67P/Churyumov-Gerasimenko near perihelionShow others and affiliations
2017 (English)In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 469, p. S142-S148Article in journal (Refereed) Published
Abstract [en]
In 2015 August, comet 67P/Churyumov-Gerasimenko, the target comet of the ESA Rosetta mission, reached its perihelion at similar to 1.24 au. Here, we estimate for a three-day period near perihelion, effective ion speeds at distances similar to 200-250 km from the nucleus. We utilize two different methods combining measurements from the Rosetta Plasma Consortium (RPC)/Mutual Impedance Probe with measurements either from the RPC/Langmuir Probe or from the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA)/Comet Pressure Sensor (COPS) (the latter method can only be applied to estimate the effective ion drift speed). The obtained ion speeds, typically in the range 2-8 km s(-1), are markedly higher than the expected neutral outflow velocity of similar to 1 km s(-1). This indicates that the ions were de-coupled from the neutrals before reaching the spacecraft location and that they had undergone acceleration along electric fields, not necessarily limited to acceleration along ambipolar electric fields in the radial direction. For the limited time period studied, we see indications that at increasing distances from the nucleus, the fraction of the ions' kinetic energy associated with radial drift motion is decreasing.
Place, publisher, year, edition, pages
2017. Vol. 469, p. S142-S148
Keywords [en]
molecular processes, comets: individual: 67P/Churyumov-Gerasimenko
National Category
Astronomy, Astrophysics and Cosmology Fusion, Plasma and Space Physics
Identifiers
URN: urn:nbn:se:kth:diva-273867DOI: 10.1093/mnras/stx1472ISI: 000443940500014OAI: oai:DiVA.org:kth-273867DiVA, id: diva2:1433650
Conference
International Conference on Cometary Science - Comets - A New Vision after Rosetta and Philae, NOV 14-18, 2016, Toulouse, France
Funder
Swedish Research Council, 621-2013-4191Swedish Research Council, 621-2014-5526Swedish National Space Board, 109/02Swedish National Space Board, 135/13Swedish National Space Board, 166/14Swedish National Space Board, 114/13
Note
QC 20201021
2020-06-012020-06-012024-01-18Bibliographically approved