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Ion acoustic waves at comet 67P/Churyumov-Gerasimenko: Observations and computations

dc.contributor.authorGunell, H.
dc.contributor.authorNilsson, H.
dc.contributor.authorHamrin, M.
dc.contributor.authorEriksson, A.
dc.contributor.authorOdelstad, E.
dc.contributor.authorMaggiolo, R.
dc.contributor.authorHenri, P.
dc.contributor.authorVallieres, X.
dc.contributor.authorAltwegg, K.
dc.contributor.authorTzou, C.-Y.
dc.contributor.authorRubin, M.
dc.contributor.authorGlassmeier, K.-H.
dc.contributor.authorStenberg Wieser, G.
dc.contributor.authorSimon Wedlund, C.
dc.contributor.authorDe Keyser, J.
dc.contributor.authorDhooghe, F.
dc.contributor.authorCessateur, G.
dc.contributor.authorGibbons, A.
dc.date2017
dc.date.accessioned2017-04-07T10:29:04Z
dc.date.available2017-04-07T10:29:04Z
dc.identifier.urihttps://orfeo.belnet.be/handle/internal/5042
dc.descriptionContext. On 20 January 2015 the Rosetta spacecraft was at a heliocentric distance of 2.5 AU, accompanying comet 67P/Churyumov-Gerasimenko on its journey toward the Sun. The Ion Composition Analyser (RPC-ICA), other instruments of the Rosetta Plasma Consortium, and the ROSINA instrument made observations relevant to the generation of plasma waves in the cometary environment. Aims. Observations of plasma waves by the Rosetta Plasma Consortium Langmuir probe (RPC-LAP) can be explained by dispersion relations calculated based on measurements of ions by the Rosetta Plasma Consortium Ion Composition Analyser (RPC-ICA), and this gives insight into the relationship between plasma phenomena and the neutral coma, which is observed by the Comet Pressure Sensor of the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis instrument (ROSINA-COPS). Methods. We use the simple pole expansion technique to compute dispersion relations for waves on ion timescales based on the observed ion distribution functions. These dispersion relations are then compared to the waves that are observed. Data from the instruments RPC-LAP, RPC-ICA and the mutual impedance probe (RPC-MIP) are compared to find the best estimate of the plasma density. Results. We find that ion acoustic waves are present in the plasma at comet 67P/Churyumov-Gerasimenko, where the major ion species is H2O+. The bulk of the ion distribution is cold, kBTi = 0.01 eV when the ion acoustic waves are observed. At times when the neutral density is high, ions are heated through acceleration by the solar wind electric field and scattered in collisions with the neutrals. This process heats the ions to about 1 eV, which leads to significant damping of the ion acoustic waves. Conclusions. In conclusion, we show that ion acoustic waves appear in the H2O+ plasmas at comet 67P/Churyumov-Gerasimenko and how the interaction between the neutral and ion populations affects the wave properties.
dc.languageeng
dc.titleIon acoustic waves at comet 67P/Churyumov-Gerasimenko: Observations and computations
dc.typeArticle
dc.subject.frascatiPhysical sciences
dc.audienceScientific
dc.subject.freeAcoustic impedance
dc.subject.freeDispersion (waves)
dc.subject.freeDispersions
dc.subject.freeDistribution functions
dc.subject.freeElectric fields
dc.subject.freeIon acoustic waves
dc.subject.freeIons
dc.subject.freeOrbits
dc.subject.freeParticle spectrometers
dc.subject.freePlasma (human)
dc.subject.freePlasma density
dc.subject.freePlasma waves
dc.subject.freeProbes
dc.subject.freeQuantum theory
dc.subject.freeWaves
dc.subject.free67p/churyumov-gerasimenko
dc.subject.freeComets: general
dc.subject.freeComets: individual: 67P/Churyumov-Gerasimenko
dc.subject.freeDispersion relations
dc.subject.freeHeliocentric distances
dc.subject.freeInstrumentation: detectors
dc.subject.freeMethods:analytical
dc.subject.freeMutual impedance probes
dc.subject.freeAcoustic waves
dc.source.titleAstronomy and Astrophysics
dc.source.volume600
dc.source.pageA3
Orfeo.peerreviewedYes
dc.identifier.doi10.1051/0004-6361/201629801
dc.identifier.scopus2-s2.0-85015776596


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