Show simple item record

dc.contributor.authorWexler, David
dc.contributor.authorHollweg, J. V.
dc.contributor.authorEfimov, A. I.
dc.contributor.authorLukanina, L. A.
dc.contributor.authorCoster, Anthea
dc.contributor.authorVierinen, Juha
dc.contributor.authorJensen, E. A.
dc.date.accessioned2019-06-07T11:34:28Z
dc.date.available2019-06-07T11:34:28Z
dc.date.issued2019-01-31
dc.description.abstractFluctuations in plasma electron density may play a role in solar coronal energy transport and the dissipation of wave energy. Transcoronal spacecraft radio sounding observations reveal frequency fluctuations (FFs) that encode the electron number density disturbances, allowing an exploration of the coronal compressive wave and advected inhomogeneity models. Primary FF observations from MESSENGER 2009 and published FF residuals from HELIOS 1975–1976 superior conjunctions were combined to produce a composite view of equatorial region FF near solar minimum over solar offset range 1.4–25R ⊙. Methods to estimate the electron number density fluctuation variance from the observed FF were developed. We created a simple stacked, magnetically structured slab model that incorporated both propagating slow density waves and advected spatial density variations to explain the observed FF. Slow density waves accounted for most of the FF at low solar offset, while spatial density inhomogeneities advected at solar wind speed dominated above the sonic point at 6R ⊙. Corresponding spatial scales ranged 1–38 Mm, with scales above 10 Mm contributing most to FF variance. Magnetic structuring of the model introduced radial elongation anistropy at lower solar offsets, but geometric conditions for isotropy were achieved as the slab correlation scales increased further out in the corona. The model produced agreement with the FF observations up to 12R ⊙. FF analysis provides information on electron density fluctuations in the solar corona, and should take into account the background compressive slow waves and solar wind-related advection of quasi-static spatial density variations.en_US
dc.descriptionSource at <a href=https://doi.org/10.3847/1538-4357/aaf6a8>https://doi.org/10.3847/1538-4357/aaf6a8</a>.en_US
dc.identifier.citationWexler D.B., Hollweg, J.V., Efimov, A.I., Lukanina, L.A., Coster, A.J., Vierinen, J. & Jensen, E.A. (2019). Spacecraft Radio Frequency Fluctuations in the Solar Corona: A MESSENGER–HELIOS Composite Study. <i>Astrophysical Journal, 871</i>(2), 202. https://doi.org/10.3847/1538-4357/aaf6a8en_US
dc.identifier.cristinIDFRIDAID 1674213
dc.identifier.issn0004-637X
dc.identifier.issn1538-4357
dc.identifier.urihttps://hdl.handle.net/10037/15478
dc.language.isoengen_US
dc.publisherAmerican Astronomical Society / Institute of Physicsen_US
dc.relation.journalAstrophysical Journal
dc.rights.accessRightsopenAccessen_US
dc.subjectVDP::Mathematics and natural science: 400::Physics: 430::Astrophysics, astronomy: 438en_US
dc.subjectVDP::Matematikk og Naturvitenskap: 400::Fysikk: 430::Astrofysikk, astronomi: 438en_US
dc.subjectSun: coronaen_US
dc.subjectSun: oscillationsen_US
dc.subjectsolar winden_US
dc.subjectturbulenceen_US
dc.subjectwavesen_US
dc.titleSpacecraft Radio Frequency Fluctuations in the Solar Corona: A MESSENGER–HELIOS Composite Studyen_US
dc.typeJournal articleen_US
dc.typeTidsskriftartikkelen_US
dc.typePeer revieweden_US


File(s) in this item

Thumbnail

This item appears in the following collection(s)

Show simple item record