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| Titel |
Variations of the helium content across interplanetary shocks |
| VerfasserIn |
Petr Cagas, Jana Safrankova, Zdenek Nemecek, Lubomir Prech, Georgy N. Zastenker |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250109914
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| Publikation (Nr.) |
 EGU/EGU2015-9868.pdf |
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| Zusammenfassung |
| Changes of the abundance of heavy species observed in the solar wind are usually
attributed to spacecraft encounters with streams emanating from different places and
altitudes in the source region and their further evolution is considered as being
negligible. These conclusions are based on the analysis of highly averaged data and
much less attention was devoted to variations on the time scale of seconds. The
BMSW instrument onboard the Spektr-R spacecraft provides high-time resolution
measurements of the helium and proton fluxes and proton velocity, density, and
temperature that are suitable for investigations of rapid variations. In this paper, we
compare measurements of variations of the helium content across interplanetary
(IP) shocks in two points (Spektr-R and Wind) separated about 200ÂRE with a
focus on the changes of helium abundance on this scale. The case study shows
that the proton density exhibits a smooth profile after the IP shock in the data of
both spacecraft, but the helium content is highly variable. Our analysis provides
a clear evidence that the abrupt changes of the helium content are caused by the
turbulence excited by the IP shock. It is important to note that the changes of protons
and helium content are not correlated, thus the helium enhancements cannot be
attributed to compressional MHD waves because both species vary independently. |
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