Influence of collisions on ion dynamics in the inner comae of four comets

File Description SizeFormat 
Mandt_et_al_accepted.pdfAccepted version1.46 MBAdobe PDFView/Open
Title: Influence of collisions on ion dynamics in the inner comae of four comets
Authors: Mandt, KE
Eriksson, A
Beth, A
Galand, M
Vigren, E
Item Type: Journal Article
Abstract: Context. Collisions between cometary neutrals in the inner coma of a comet and cometary ions that have been picked up into the solar wind flow and return to the coma lead to the formation of a broad inner boundary known as a collisionopause. This boundary is produced by a combination of charge transfer and chemical reactions, both of which are important at the location of the collisionopause boundary. Four spacecraft measured ion densities and velocities in the inner region of comets, exploring the part of the coma where an ion-neutral collisionopause boundary is expected to form. Aims. The aims are to determine the dominant physics behind the formation of the ion-neutral collisionopause and to evaluate where this boundary has been observed by spacecraft. Methods. We evaluated observations from three spacecraft at four different comets to determine if a collisionopause boundary was observed based on the reported ion velocities. We compared the measured location of the ion-neutral collisionopause with measurements of the collision cross sections to evaluate whether chemistry or charge exchange are more important at the location where the collisionopause is observed. Results. Based on measurements of the cross sections for charge transfer and for chemical reactions, the boundary observed by Rosetta appears to be the location where chemistry becomes the more probable result of a collision between H2O and H2O+ than charge exchange. Comparisons with ion observations made by Deep Space 1 at 19P/Borrelly and Giotto at 1P/Halley and 26P/Grigg-Skjellerup show that similar boundaries were observed at 19P/Borrelly and 1P/Halley. The ion composition measurements made by Giotto at Halley confirm that chemistry becomes more important inside of this boundary and that electron-ion dissociative recombination is a driver for the reported ion pileup boundary.
Issue Date: 20-Sep-2019
Date of Acceptance: 5-Mar-2019
URI: http://hdl.handle.net/10044/1/73818
DOI: https://doi.org/10.1051/0004-6361/201834828
ISSN: 1432-0746
Publisher: EDP SCIENCES S A
Start Page: 1
End Page: 8
Journal / Book Title: ASTRONOMY & ASTROPHYSICS
Volume: 630
Copyright Statement: © ESO 2019.
Sponsor/Funder: Science and Technology Facilities Council (STFC)
Funder's Grant Number: ST/N000692/1
Keywords: Science & Technology
Physical Sciences
Astronomy & Astrophysics
molecular processes
plasmas
comets: individual: 67P/Churyumov-Gerasimenko
comets: individual: 1P/Halley
comets: individual: 19P/Borelly
comets: individual: 26P/Grigg-Skjellerup
SOLAR-WIND INTERACTION
DIAMAGNETIC CAVITY
CROSS-SECTIONS
ROSETTA
PLASMA
RPC
HALLEY
EVOLUTION
GIOTTO
67P
Science & Technology
Physical Sciences
Astronomy & Astrophysics
molecular processes
plasmas
comets: individual: 67P/Churyumov-Gerasimenko
comets: individual: 1P/Halley
comets: individual: 19P/Borelly
comets: individual: 26P/Grigg-Skjellerup
SOLAR-WIND INTERACTION
DIAMAGNETIC CAVITY
CROSS-SECTIONS
ROSETTA
PLASMA
RPC
HALLEY
EVOLUTION
GIOTTO
67P
Astronomy & Astrophysics
0201 Astronomical and Space Sciences
Publication Status: Published
Article Number: ARTN A48
Online Publication Date: 2019-09-20
Appears in Collections:Space and Atmospheric Physics
Physics



Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

Creative Commons