Effective ion speeds at ∼200–250 km from comet 67P/Churyumov–Gerasimenko near perihelion - INSU - Institut national des sciences de l'Univers Accéder directement au contenu
Article Dans Une Revue Monthly Notices of the Royal Astronomical Society Année : 2017

Effective ion speeds at ∼200–250 km from comet 67P/Churyumov–Gerasimenko near perihelion

Résumé

In 2015 August, comet 67P/Churyumov–Gerasimenko, the target comet of the ESA Rosetta mission, reached its perihelion at ∼1.24 au. Here, we estimate for a three-day period near perihelion , effective ion speeds at distances ∼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 ∼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.
Fichier principal
Vignette du fichier
stx1472.pdf (1.43 Mo) Télécharger le fichier
Origine : Fichiers éditeurs autorisés sur une archive ouverte
Loading...

Dates et versions

insu-01685253 , version 1 (16-01-2018)

Identifiants

Citer

E. Vigren, M. André, N. J. T. Edberg, I. A. D. Engelhardt, A. I. Eriksson, et al.. Effective ion speeds at ∼200–250 km from comet 67P/Churyumov–Gerasimenko near perihelion. Monthly Notices of the Royal Astronomical Society, 2017, 469 (Suppl_2), pp.S142-S148. ⟨10.1093/mnras/stx1472⟩. ⟨insu-01685253⟩
139 Consultations
86 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More