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| Titel |
Variations of helium abundance in the solar wind and its changes across IP shocks |
| VerfasserIn |
Tereza Durovcova, Petr Cagas, Jana Safrankova, Zdenek Nemecek, Georgy N. Zastenker |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250123705
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| Publikation (Nr.) |
 EGU/EGU2016-3002.pdf |
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| Zusammenfassung |
| The relative abundance of helium in the solar wind mediates the physical processes ongoing
at the Sun surface. The ratio of alpha and proton densities is believed to characterize the
source of the currently observed solar wind stream. Thus abrupt changes of this ratio are
usually associated with encounters of the boundary between flux tubes emanating from
different sources. However, a preliminary analysis of the data from the BMSW instrument
(the Spektr-R spacecraft) shows that the He abundance can rapidly vary over much shorter
time scales and we suggest that the differential motion of the proton and alpha
solar wind components provides the driving energy for turbulence that is able to
create the observed fast changes of the alpha/proton ratio. The differential velocity
would significantly change across interplanetary shocks, whereas the density ratio
does not. Thus, to separate the changes corresponding to flux tube crossings from
those caused by turbulence within these flux tubes, we analyze the fast variations
of helium/proton ratios prior to and after IP shocks. We compare measurements
of two spacecraft (Spektr-R around the Earth, and Wind in L1 point) across the
interplanetary shocks and focus on the variations of the helium abundance in a connection
with the changes of the alpha/proton differential velocity. The two-case study is
complemented with statistical analysis of correlations between related quantities. |
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