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| Titel |
Multi-coordinate System (Ecliptic, Galactic, ISMF) Spectral Analysis of Heliospheric ENA Emissions Using Cassini/INCA Measurements |
| VerfasserIn |
K. Dialynas, S. Krimigis, D. Mitchell, E. Roelof, R. Decker |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250061229
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| Zusammenfassung |
| Energetic Neutral Atom (ENA) images have led to a number of unexpected heliospheric
signatures such as the “Belt” and the “Ribbon” (Krimigis et al, McComas et al, 2009) and to
new aspects of the physics of the heliosphere that were substantially at variance
with theoretical models (e.g. the relative symmetry between the “nose” and “tail”
directions, and the need for a stronger interstellar magnetic field than assumed
before in order to balance the non-thermal pickup-ion pressure in the heliosheath).
With this study we use all-sky energy-resolved ENA maps obtained by the INCA
instrument onboard Cassini over the time period 2003 to 2009, in 4 discrete energy
passbands (~5.4 to ~55 keV). We investigate the geometrical characteristics of the
Belt, and spectral analyses are performed to further examine its possible energy
dependence and possible variability with time. We conclude that: (a) The high flux
ENA Belt is identified in the energy range of 5 to 55 keV and is moderately well
organized in galactic coordinates, because the ENA minima appear in the vicinity
of the North and South Galactic poles, (b) using standard criteria (B-
R~0), the
deviation of the ENA emissions from the equator is effectively minimized in a
rotated frame (that we interpret as ISMF) where its North Pole points towards 190o
Ecliptic Longitude and 15o Ecliptic Latitude, (c) ENA spectra show a power law
form in energy, that can be fitted with a single function presenting higher spectral
slopes in the Belt region and lower outside (3.4< γ 35 keV), (f) in the low intensity regions INCA ENA
count rate profiles as a function of time do not match the measured cosmic ray
profiles, indicating that the ENA emissions detected by INCA are foreground ENA’s. |
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