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dc.contributor.authorVech, Daniel
dc.contributor.authorKlein, Kristopher G.
dc.contributor.authorKasper, J. C.
dc.date.accessioned2017-12-20T19:13:01Z
dc.date.available2017-12-20T19:13:01Z
dc.date.issued2017-11-16
dc.identifier.citationNature of Stochastic Ion Heating in the Solar Wind: Testing the Dependence on Plasma Beta and Turbulence Amplitude 2017, 850 (1):L11 The Astrophysical Journalen
dc.identifier.issn2041-8213
dc.identifier.doi10.3847/2041-8213/aa9887
dc.identifier.urihttp://hdl.handle.net/10150/626264
dc.description.abstractThe solar wind undergoes significant heating as it propagates away from the Sun; the exact mechanisms responsible for this heating are not yet fully understood. We present for the first time a statistical test for one of the proposed mechanisms: stochastic ion heating. We use the amplitude of magnetic field fluctuations near the proton gyroscale as a proxy for the ratio of gyroscale velocity fluctuations to perpendicular (with respect to the magnetic field) proton thermal speed, defined as epsilon(p). Enhanced proton temperatures are observed when epsilon(p) is larger than a critical value (similar to 0.019-0.025). This enhancement strongly depends on the proton plasma beta (beta parallel to(p)); when beta parallel to(p) << 1 only the perpendicular proton temperature T-perpendicular to increases, while for beta parallel to(p) similar to 1 increased parallel and perpendicular proton temperatures are both observed. For epsilon(p) smaller than the critical value and beta parallel to(p) << 1 no enhancement of Tp is observed, while for beta parallel to(p) similar to 1 minor increases in T-parallel to are measured. The observed change of proton temperatures across a critical threshold for velocity fluctuations is in agreement with the stochastic ion heating model of Chandran et al. We find that epsilon(p) > epsilon(crit) in 76% of the studied periods, implying that stochastic heating may operate most of the time in the solar wind at 1 au.
dc.description.sponsorshipNASA [NNX16AM23G, NNX14AR78G]en
dc.language.isoenen
dc.publisherIOP PUBLISHING LTDen
dc.relation.urlhttp://stacks.iop.org/2041-8205/850/i=1/a=L11?key=crossref.6b0ff345ea76324426771fad0f6cbc2ben
dc.rights© 2017. The American Astronomical Society.en
dc.subjectplasmasen
dc.subjectsolar winden
dc.subjectturbulenceen
dc.subjectwavesen
dc.titleNature of Stochastic Ion Heating in the Solar Wind: Testing the Dependence on Plasma Beta and Turbulence Amplitudeen
dc.typeArticleen
dc.contributor.departmentUniv Arizona, Lunar & Planetary Laben
dc.identifier.journalThe Astrophysical Journal Lettersen
dc.description.collectioninformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.en
dc.eprint.versionFinal published versionen
refterms.dateFOA2018-09-12T00:39:41Z
html.description.abstractThe solar wind undergoes significant heating as it propagates away from the Sun; the exact mechanisms responsible for this heating are not yet fully understood. We present for the first time a statistical test for one of the proposed mechanisms: stochastic ion heating. We use the amplitude of magnetic field fluctuations near the proton gyroscale as a proxy for the ratio of gyroscale velocity fluctuations to perpendicular (with respect to the magnetic field) proton thermal speed, defined as epsilon(p). Enhanced proton temperatures are observed when epsilon(p) is larger than a critical value (similar to 0.019-0.025). This enhancement strongly depends on the proton plasma beta (beta parallel to(p)); when beta parallel to(p) << 1 only the perpendicular proton temperature T-perpendicular to increases, while for beta parallel to(p) similar to 1 increased parallel and perpendicular proton temperatures are both observed. For epsilon(p) smaller than the critical value and beta parallel to(p) << 1 no enhancement of Tp is observed, while for beta parallel to(p) similar to 1 minor increases in T-parallel to are measured. The observed change of proton temperatures across a critical threshold for velocity fluctuations is in agreement with the stochastic ion heating model of Chandran et al. We find that epsilon(p) > epsilon(crit) in 76% of the studied periods, implying that stochastic heating may operate most of the time in the solar wind at 1 au.


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