Change search
Link to record
Permanent link

Direct link
BETA
Publications (10 of 16) Show all publications
Wedlund, C. S., Bodewits, D., Alho, M., Hoekstra, R., Behar, E., Gronoff, G., . . . Beth, A. (2019). Solar wind charge exchange in cometary atmospheres: I. Charge-changing and ionization cross sections for He and H particles in H2O. Astronomy and Astrophysics, 630, Article ID A35.
Open this publication in new window or tab >>Solar wind charge exchange in cometary atmospheres: I. Charge-changing and ionization cross sections for He and H particles in H2O
Show others...
2019 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 630, article id A35Article in journal (Refereed) Published
Abstract [en]

Context. Solar wind charge-changing reactions are of paramount importance to the physico-chemistry of the atmosphere of a comet, mass-loading the solar wind through an effective conversion of fast light solar wind ions into slow heavy cometary ions.

Aims. To understand these processes and place them in the context of a solar wind plasma interacting with a neutral atmosphere, numerical or analytical models are necessary. Inputs of these models, such as collision cross sections and chemistry, are crucial.

Methods. Book-keeping and fitting of experimentally measured charge-changing and ionization cross sections of hydrogen and helium particles in a water gas are discussed, with emphasis on the low-energy/low-velocity range that is characteristic of solar wind bulk speeds (<20 keV u−1/2000 km s−1).

Results. We provide polynomial fits for cross sections of charge-changing and ionization reactions, and list the experimental needs for future studies. To take into account the energy distribution of the solar wind, we calculated Maxwellian-averaged cross sections and fitted them with bivariate polynomials for solar wind temperatures ranging from 105 to 106 K (12–130 eV).

Conclusions. Single- and double-electron captures by He2+ dominate at typical solar wind speeds. Correspondingly, single-electron capture by H+ and single-electron loss by H dominate at these speeds, resulting in the production of energetic neutral atoms (ENAs). Ionization cross sections all peak at energies above 20 keV and are expected to play a moderate role in the total ion production. However, the effect of solar wind Maxwellian temperatures is found to be maximum for cross sections peaking at higher energies, suggesting that local heating at shock structures in cometary and planetary environments may favor processes previously thought to be negligible. This study is the first part in a series of three on charge exchange and ionization processes at comets, with a specific application to comet 67P/Churyumov-Gerasimenko and the Rosetta mission.

Place, publisher, year, edition, pages
EDP Sciences, 2019
Keywords
comets: general, comets: individual: 67P/Churyumov-Gerasimenko, instrumentation: detectors / solar wind, methods: data analysis / plasmas
National Category
Aerospace Engineering
Research subject
Atmospheric science
Identifiers
urn:nbn:se:ltu:diva-76348 (URN)10.1051/0004-6361/201834848 (DOI)000486989400034 ()
Note

Validerad;2019;Nivå 2;2019-10-10 (johcin)

Available from: 2019-10-10 Created: 2019-10-10 Last updated: 2019-10-10Bibliographically approved
Wedlund, C. S., Behar, E., Kallio, E., Nilsson, H., Alho, M., Gunell, H., . . . Hoekstra, R. (2019). Solar wind charge exchange in cometary atmospheres: II. Analytical model. Astronomy and Astrophysics, 630, Article ID A36.
Open this publication in new window or tab >>Solar wind charge exchange in cometary atmospheres: II. Analytical model
Show others...
2019 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 630, article id A36Article in journal (Refereed) Published
Abstract [en]

Context. Solar wind charge-changing reactions are of paramount importance to the physico-chemistry of the atmosphere of a comet because they mass-load the solar wind through an effective conversion of fast, light solar wind ions into slow, heavy cometary ions. The ESA/Rosetta mission to comet 67P/Churyumov-Gerasimenko (67P) provided a unique opportunity to study charge-changing processes in situ.

Aims. To understand the role of charge-changing reactions in the evolution of the solar wind plasma and to interpret the complex in situ measurements made by Rosetta, numerical or analytical models are necessary.

Methods. An extended analytical formalism describing solar wind charge-changing processes at comets along solar wind streamlines is presented. It is based on a thorough book-keeping of available charge-changing cross sections of hydrogen and helium particles in a water gas.

Results. After presenting a general 1D solution of charge exchange at comets, we study the theoretical dependence of charge-state distributions of (He2+, He+, He0) and (H+, H0, H) on solar wind parameters at comet 67P. We show that double charge exchange for the He2+−H2O system plays an important role below a solar wind bulk speed of 200 km s−1, resulting in the production of He energetic neutral atoms, whereas stripping reactions can in general be neglected. Retrievals of outgassing rates and solar wind upstream fluxes from local Rosetta measurements deep in the coma are discussed. Solar wind ion temperature effects at 400 km s−1 solar wind speed are well contained during the Rosetta mission.

Conclusions. As the comet approaches perihelion, the model predicts a sharp decrease of solar wind ion fluxes by almost one order of magnitude at the location of Rosetta, forming in effect a solar wind ion cavity. This study is the second part of a series of three on solar wind charge-exchange and ionization processes at comets, with a specific application to comet 67P and the Rosetta mission.

Place, publisher, year, edition, pages
EDP Sciences, 2019
Keywords
comets: general, comets: individual: 67P/Churyumov-Gerasimenko, instrumentation: detectors / waves / solar wind, methods: analytical
National Category
Aerospace Engineering
Research subject
Atmospheric science
Identifiers
urn:nbn:se:ltu:diva-76349 (URN)10.1051/0004-6361/201834874 (DOI)000486989400035 ()
Note

Validerad;2019;Nivå 2;2019-10-10 (johcin)

Available from: 2019-10-10 Created: 2019-10-10 Last updated: 2019-10-10Bibliographically approved
Wedlund, C. S., Behar, E., Nilsson, H., Alho, M., Kallio, E., Gunell, H., . . . Hoekstra, R. (2019). Solar wind charge exchange in cometary atmospheres: III. Results from the Rosetta mission to comet 67P/Churyumov-Gerasimenko. Astronomy and Astrophysics, 630, Article ID A37.
Open this publication in new window or tab >>Solar wind charge exchange in cometary atmospheres: III. Results from the Rosetta mission to comet 67P/Churyumov-Gerasimenko
Show others...
2019 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 630, article id A37Article in journal (Refereed) Published
Abstract [en]

Context. Solar wind charge-changing reactions are of paramount importance to the physico-chemistry of the atmosphere of a comet. The ESA/Rosetta mission to comet 67P/Churyumov-Gerasimenko (67P) provides a unique opportunity to study charge-changing processes in situ.

Aims. To understand the role of these reactions in the evolution of the solar wind plasma and interpret the complex in situ measurements made by Rosetta, numerical or analytical models are necessary.

Methods. We used an extended analytical formalism describing solar wind charge-changing processes at comets along solar wind streamlines. The model is driven by solar wind ion measurements from the Rosetta Plasma Consortium-Ion Composition Analyser (RPC-ICA) and neutral density observations from the Rosetta Spectrometer for Ion and Neutral Analysis-Comet Pressure Sensor (ROSINA-COPS), as well as by charge-changing cross sections of hydrogen and helium particles in a water gas.

Results. A mission-wide overview of charge-changing efficiencies at comet 67P is presented. Electron capture cross sections dominate and favor the production of He and H energetic neutral atoms (ENAs), with fluxes expected to rival those of H+ and He2+ ions.

Conclusions. Neutral outgassing rates are retrieved from local RPC-ICA flux measurements and match ROSINA estimates very well throughout the mission. From the model, we find that solar wind charge exchange is unable to fully explain the magnitude of the sharp drop in solar wind ion fluxes observed by Rosetta for heliocentric distances below 2.5 AU. This is likely because the model does not take the relative ion dynamics into account and to a lesser extent because it ignores the formation of bow-shock-like structures upstream of the nucleus. This work also shows that the ionization by solar extreme-ultraviolet radiation and energetic electrons dominates the source of cometary ions, although solar wind contributions may be significant during isolated events.

Place, publisher, year, edition, pages
EDP Sciences, 2019
Keywords
comets: general, comets: individual: 67P/Churyumov-Gerasimenko, instrumentation: detectors, solar wind, methods: analytical, plasmas
National Category
Aerospace Engineering
Research subject
Atmospheric science
Identifiers
urn:nbn:se:ltu:diva-76342 (URN)10.1051/0004-6361/201834881 (DOI)000486989400036 ()
Note

Validerad;2019;Nivå 2;2019-10-10 (johcin)

Available from: 2019-10-10 Created: 2019-10-10 Last updated: 2019-10-10Bibliographically approved
Berecic, L., Behar, E., Nilsson, H., Nicolaou, G., Stenberg-Wieser, G., Wieser, M. & Goetz, C. (2018). Cometary ion dynamics observed in the close vicinity of comet 67P/Churyumov-Gerasimenko during the intermediate activity period. Astronomy and Astrophysics, 613, 1-8
Open this publication in new window or tab >>Cometary ion dynamics observed in the close vicinity of comet 67P/Churyumov-Gerasimenko during the intermediate activity period
Show others...
2018 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 613, p. 1-8Article in journal (Refereed) Published
Abstract [en]

Aims.Cometary ions are constantly produced in the coma, and once produced they are accelerated and eventually escape the coma.We describe and interpret the dynamics of the cometary ion flow, of an intermediate active comet, very close to the nucleus and in theterminator plane.Methods.We analysed in situ ion and magnetic field measurements, and characterise the velocity distribution functions (mostly usingplasma moments). We propose a statistical approach over a period of one month.Results.On average, two populations were observed, separated in phase space. The motion of the first is governed by its interactionwith the solar wind farther upstream, while the second one is accelerated in the inner coma and displays characteristics compatiblewith an ambipolar electric field. Both populations display a consistent anti-sunward velocity component.Conclusions.Cometary ions born in different regions of the coma are seen close to the nucleus of comet 67P/Churyumov–Gerasimenko with distinct motions governed in one case by the solar wind electric field and in the other case by the position relative tothe nucleus. A consistent anti-sunward component is observed for all cometary ions. An asymmetry is found in the average cometaryion density in a solar wind electric field reference frame, with higher density in the negative (south) electric field hemisphere. Thereis no corresponding signature in the average magnetic field strengt

Place, publisher, year, edition, pages
EDP Sciences, 2018
National Category
Fusion, Plasma and Space Physics Aerospace Engineering
Research subject
Atmospheric science
Identifiers
urn:nbn:se:ltu:diva-68784 (URN)10.1051/0004-6361/201732082 (DOI)000433880200003 ()
Note

Validerad;2018;Nivå 2;2018-06-14 (andbra)

Available from: 2018-05-18 Created: 2018-05-18 Last updated: 2018-06-21Bibliographically approved
Behar, E., Tabone, B. & Nilsson, H. (2018). Dawn-dusk asymmetry induced by the Parker spiral angle in the plasma dynamics around comet 67P/Churyumov-Gerasimenko. Monthly notices of the Royal Astronomical Society, 478(2), 1570-1575
Open this publication in new window or tab >>Dawn-dusk asymmetry induced by the Parker spiral angle in the plasma dynamics around comet 67P/Churyumov-Gerasimenko
2018 (English)In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 478, no 2, p. 1570-1575Article in journal (Refereed) Published
Abstract [en]

When interacting, the solar wind and the ionised atmosphere of a comet exchange energy and momentum. Our aim is to understand the influence of the average Parker spiral configuration of the solar wind magnetic field on this interaction. We compare the theoretical expectations of an analytical generalised gyromotion with Rosetta observations at comet 67P/Churyumov-Gerasimenko. A statistical approach allows one to overcome the lack of upstream solar wind measurement. We find that additionally to their acceleration along (for cometary pick-up ions) or against (for solar wind ions) the upstream electric field orientation and sense, the cometary pick-up ions are drifting towards the dawn side of the coma, while the solar wind ions are drifting towards the dusk side of the coma, independent of the heliocentric distance. The dynamics of the interaction is not taking place in a plane, as often assumed in previous works.

Place, publisher, year, edition, pages
Royal Astronomical Society, 2018
National Category
Fusion, Plasma and Space Physics Aerospace Engineering
Research subject
Atmospheric science
Identifiers
urn:nbn:se:ltu:diva-68782 (URN)10.1093/mnras/sty1111 (DOI)000439547400010 ()2-s2.0-85048857464 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-06-19 (andbra)

Available from: 2018-05-18 Created: 2018-05-18 Last updated: 2018-08-09Bibliographically approved
Behar, E., Tabone, B., Saillenfest, M., Henri, P., Deca, J., Lindkvist, J., . . . Nilsson, H. (2018). Solar wind dynamics around a comet: A 2D semi-analytical kinetic model. Astronomy and Astrophysics, 620, Article ID A35.
Open this publication in new window or tab >>Solar wind dynamics around a comet: A 2D semi-analytical kinetic model
Show others...
2018 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 620, article id A35Article in journal (Refereed) Published
Abstract [en]

Aims.We aim at analytically modelling the solar wind proton trajectories during their interaction with a partially ionised cometaryatmosphere, not in terms of bulk properties of the flow but in terms of single particle dynamics.Methods.We first derive a generalised gyromotion, in which the electric field is reduced to its motional component. Steady-stateis assumed, and simplified models of the cometary density and of the electron fluid are used to express the force experienced byindividual solar wind protons during the interaction.Results.A three-dimensional (3D) analytical expression of the gyration of two interacting plasma beams is obtained. Applying it to acomet case, the force on protons is always perpendicular to their velocity and has an amplitude proportional to 1/r2. The solar winddeflection is obtained at any point in space. The resulting picture presents a caustic of intersecting trajectories, and a circular regionis found that is completely free of particles. The particles do not lose any kinetic energy and this absence of deceleration, togetherwith the solar wind deflection pattern and the presence of a solar wind ion cavity, is in good agreement with the general results of theRosettamission.Conclusions.The qualitative match between the model and thein situdata highlights how dominant the motional electric field isthroughout most of the interaction region for the solar wind proton dynamics. The model provides a simple general kinetic descriptionof how momentum is transferred between these two collisionless plasmas. It also shows the potential of this semi-analytical modelfor a systematic quantitative comparison to the data.

Place, publisher, year, edition, pages
EDP Sciences, 2018
National Category
Fusion, Plasma and Space Physics Aerospace Engineering
Research subject
Atmospheric science
Identifiers
urn:nbn:se:ltu:diva-68781 (URN)10.1051/0004-6361/201832736 (DOI)000451249600003 ()2-s2.0-85051991586 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-12-05 (svasva)

Available from: 2018-05-18 Created: 2018-05-18 Last updated: 2019-01-10Bibliographically approved
Saillenfest, M., Tabone, B. & Behar, E. (2018). Solar wind dynamics around a comet: The paradigmatic inverse-square-law model. Astronomy and Astrophysics, 617, Article ID A99.
Open this publication in new window or tab >>Solar wind dynamics around a comet: The paradigmatic inverse-square-law model
2018 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 617, article id A99Article in journal (Refereed) Published
Abstract [en]

Aims.

Observations of solar protons near comet 67P/Churyumov-Gerasimenko (67P) by the Rosetta spacecraft can be modelled by the planar motion in an effective magnetic field proportional to 1/r(2). We aim to provide a thorough study of such dynamics, with a clear description of the behaviour of an incoming flux of particles. We will be able, then, to calibrate the free parameters of the model to Rosetta observations. 

Methods.

Basic tools of dynamical analysis are used. They lead to a definition of the relevant parameters for the system and a classification of the possible types of trajectories. Using the so-obtained formalism, the structures formed by a flux of particles coming from infinity can be studied. 

Results.

All the trajectories are parametrised by two characteristic radii, r(E) and r(C), derived from first integrals. There are three different types of motion possible divided by a separatrix corresponding to r(E) = r(C). An analytical expression of the trajectories, defined by an integral, is developed. Using this formalism, the application to a flux of particles coming from infinity (modelling the incident solar wind) gives one free parameter only, the radius r(E), which scales the problem. A circular cavity of radius 0.28 r(E) is created, as well as an overdensity curve (analogous to a caustic in optics). At each observation time, r(E) can be calibrated to Rosetta plasma measurements, giving a qualitative understanding of the solar particle dynamics (incoming direction, cavity and density map). We also deduce that, in order to properly capture the essence of the dynamics, numerical simulations of the solar wind around a comet must use simulation boxes much larger than r(E) and grids much finer than r(E).

Place, publisher, year, edition, pages
EDP Sciences, 2018
National Category
Aerospace Engineering
Research subject
Atmospheric science
Identifiers
urn:nbn:se:ltu:diva-71179 (URN)10.1051/0004-6361/201832742 (DOI)000445859100001 ()2-s2.0-85051966811 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-10-12 (johcin)

Available from: 2018-10-12 Created: 2018-10-12 Last updated: 2018-10-12Bibliographically approved
Behar, E. (2018). Solar Wind Dynamics within The Atmosphere of comet 67P/Churyumov-Gerasimenko. (Doctoral dissertation). Luleå: Luleå University of Technology
Open this publication in new window or tab >>Solar Wind Dynamics within The Atmosphere of comet 67P/Churyumov-Gerasimenko
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In this thesis, we explore the dynamics of the solar wind as it perme-ates and flows through a tenuous cometary atmosphere, with a focuson the interaction observed at comet 67P/Churyumov–Gerasimenko.

Seven comets had already been visited by nine different probes when the European spacecraft Rosetta reached comet Churyumov–Gerasimenko in August 2014. The mission was however the first to orbit its host comet, which it did for a total duration of more than two years, corre-sponding to a large part of the comet’s orbit around the Sun. This en-abled to study how the dynamics of the plasma environment evolvedas the comet itself was transformed from one of the smallest obstaclesto the solar wind in the Solar System when far away from the Sun, toa well-established magnetosphere at perihelion.

Most of our efforts tackle the early part of this transformation, when the creation of new-born cometary ions starts to induce significant disturbances to the incident flow. During this stage, a kinetic descrip-tion of the interaction is necessary, as the system of interest cannot be reduced to a hydrodynamic problem. This contrasts with the situation closer to the Sun, where a fluid treatment can be used, at Churyumov–Gerasimenko as well as at previously visited comets.

Rosetta was not a mission dedicated to plasma studies, however. It directly translates into a limited spatial coverage of the cometary plasma environment, which by its nature extends over several spatial scales. An approach solely based on the analysis of in-situ data cannot properly address the major questions on the nature and physics of the plasma environment of Churyumov–Gerasimenko. This thesis there-fore largely exploits the experimental–analytical–numerical triad of approaches. In Chapters 3 and 4 we propose simple models of the ion dynamics and of the cometary plasma environment, and these are tested against experimental and numerical data. Used together,they give a global description of the solar wind ion dynamics through the cometary atmosphere, that we explore in the 2-dimensional and 3-dimensional cases (Chapter 5). In Chapter 6, we propose a view onthe interaction and its fluid aspects when closer to the Sun.

Abstract [sv]

I  denna  avhandling  undersöks  solvindens  dynamik  när  den  flödar genom  en  tunn  kometatmosfär,  med  fokus  på  den  interaktion  somobserverats vid kometen 67P/Churyumov-Gerasimenko.

När  Rosetta  nådde  from  till  komet  67P/Churyumov–Gerasimenko  i augusti 2014 hade redan sju olika rymdfarkoster besökt nio olika ko- meter.  Rosetta  var  dock  den  första  missionen  som  cirklade  runt  en komet och följde den sedan i dess bana i totalt mer än två år. Detta motsvarade en signifikant del av hela kometens bana runt solen. Det- ta gjorde det möjligt att studera plasmats dynamiska utveckling un- der en period när kometen utvecklades från ett av de minsta hindren solvinden möter i solsystemet, när kometen är långt från solen, till enfullt utvecklad magnetosfär nära perihelion.

Avhandlingen behandlar främst den tidiga delen av denna utveckling, när nyligen joniserade molekyler från kometatmosfären börjar ge en signifikant störning i solvindens flöde. Under dessa förhållanden är en kinetisk beskrivning av växelverkan mellan solvinden och kome- tatmosfären  nödvändig.  Systemet  vi  studerar  kan  inte  reduceras  till ett hydrodynamiskt problem. Detta till skillnad från situationen när kometen är närmare solen, då växelverkan kan beskrivas med fluid- teori, för både Churyumov–Gerasimenko och de tidigare undersöktakometerna.

Rosetta var inte en mission främst ägnad åt plasma-studier. Detta med- förde begränsad rumslig täckning av de plasma-processer som äger rum, vilka äger rum över flera olika rumsskalor. Att förstå solvindens växleverkan  med  kometatmosfären  enbart  med  enpunktsmätningar låter sig därför inte göras. I detta arbete används därför en kombina- tion av experimentella data, analytiska beskrivningar och numeriska beräkningar. I kapitel 3 och 4 föreslår vi enkla modeller för att beskri- va jondynamiken och kometens plasmamiljö. Dessa testas sedan mot observationer och numeriska modeller. Tillsammans ger de en global beskrivning  av  solvindens  dynamik  när  den  flödar  genom  kometat- mosfären,  vilket  utforskas  i  både  2 och  3 dimensioner  (kapitel  5).  I kapitel 6 utforskar vi interaktionen som sker när kometen är närmaresolen, och hur den nu i högre grad kan beskrivas som en fluid.

Place, publisher, year, edition, pages
Luleå: Luleå University of Technology, 2018
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
National Category
Fusion, Plasma and Space Physics Aerospace Engineering
Research subject
Space Technology
Identifiers
urn:nbn:se:ltu:diva-68785 (URN)978-91-7790-156-3 (ISBN)978-91-7790-157-0 (ISBN)
Public defence
2018-10-12, Aulan, IRF, Rymdcampus, Kiruna, 09:00 (English)
Opponent
Supervisors
Available from: 2018-05-21 Created: 2018-05-18 Last updated: 2018-10-10Bibliographically approved
Behar, E., Nilsson, H., Alho, M., Goetz, C. & Tsurutani, B. (2017). The birth and growth of a solar wind cavity around a comet: Rosetta observations. Monthly notices of the Royal Astronomical Society, 469(Suppl. 2), S369-S403
Open this publication in new window or tab >>The birth and growth of a solar wind cavity around a comet: Rosetta observations
Show others...
2017 (English)In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 469, no Suppl. 2, p. S369-S403Article in journal (Refereed) Published
Abstract [en]

The Rosetta mission provided detailed observations of the growth of a cavity in the solar wind around comet 67P/Churyumov–Gerasimenko. As the comet approached the Sun, the plasma of cometary origin grew enough in density and size to present an obstacle to the solar wind. Our results demonstrate how the initial slight perturbations of the solar wind prefigure the formation of a solar wind cavity, with a particular interest placed on the discontinuity (solar wind cavity boundary) passing over the spacecraft. The slowing down and heating of the solar wind can be followed and understood in terms of single particle motion. We propose a simple geometric illustration that accounts for the observations, and shows how a cometary magnetosphere is seeded from the gradual steepening of an initially slight solar wind perturbation. A perspective is given concerning the difference between the diamagnetic cavity and the solar wind cavity.

Place, publisher, year, edition, pages
Oxford University Press, 2017
Keywords
acceleration of particles, plasmas, methods: data analysis, techniques: imaging spectroscopy, comets: individual: 67P/Churyumov–Gerasimenko
National Category
Fusion, Plasma and Space Physics Aerospace Engineering
Research subject
Atmospheric science
Identifiers
urn:nbn:se:ltu:diva-68779 (URN)10.1093/mnras/stx1871 (DOI)000443940500039 ()2-s2.0-85045874053 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-12-07 (marisr)

Available from: 2018-05-18 Created: 2018-05-18 Last updated: 2018-12-07Bibliographically approved
Behar, E., Nilsson, H., Wieser, G. S., Nemeth, Z., Brolles, T. & Richter, I. (2016). Mass loading at 67P/Churyumov-Gerasimenko: A case study (ed.). Geophysical Research Letters, 43(4), 1411-1418
Open this publication in new window or tab >>Mass loading at 67P/Churyumov-Gerasimenko: A case study
Show others...
2016 (English)In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 43, no 4, p. 1411-1418Article in journal (Refereed) Published
Abstract [en]

We study the dynamics of the interaction between the solar wind ions and a partially ionized atmosphere around a comet, at a distance of 2.88 AU from the Sun during a period of low nucleus activity. Comparing particle data and magnetic field data for a case study, we highlight the prime role of the solar wind electric field in the cometary ion dynamics. Cometary ion and solar wind proton flow directions evolve in a correlated manner, as expected from the theory of mass loading. We find that the main component of the accelerated cometary ion flow direction is along the antisunward direction and not along the convective electric field direction. This is interpreted as the effect of an antisunward polarization electric field adding up to the solar wind convective electric field.

National Category
Aerospace Engineering
Research subject
Atmospheric science
Identifiers
urn:nbn:se:ltu:diva-8286 (URN)10.1002/2015GL067436 (DOI)000373109000001 ()2-s2.0-84975743627 (Scopus ID)6c6ac809-0b7a-4666-8ba3-4712cf4ebf06 (Local ID)6c6ac809-0b7a-4666-8ba3-4712cf4ebf06 (Archive number)6c6ac809-0b7a-4666-8ba3-4712cf4ebf06 (OAI)
Note

Validerad; 2016; Nivå 2; 20160219 (andbra)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-0177-510x

Search in DiVA

Show all publications