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| Titel |
Energetic Neutral Atom (ENA) imaging of the heliosphere: Is the heliospheric cavity comet-like? |
| VerfasserIn |
Stamatios Krimigis, Donald Mitchell, Edmond Roelof, Robert Decker |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250036331
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| Zusammenfassung |
| The Ion and Neutral Camera (INCA), part of the Magnetospheric Imaging Instrument
(MIMI) sensor suite on the Cassini orbiter at Saturn, is an energetic neutral atom imager
designed to obtain measurements of magnetospheric phenomena, and has done so for more
than five years. When not pointing at the planet, INCA can sense ENA from other
sources, notably those traversing the interplanetary medium from the direction
of the heliosheath. Maps of such emissions (Krimigis et al, 2009) have now been
constructed spanning the energy range ~ 5 -¤ E -¤ 55 keV. Similarly, maps < 6 keV have
been obtained by the IBEX mission (McComas et al, 2009). These maps, on the
main, do not conform to the standard models of the shape of the heliosphere. The
distributions of the emissions are clearly influenced by factors over and above those
estimated from the flow of interstellar plasma. Assuming that measurements of
energetic ions by Voyagers 1, 2 in the heliosheath (Decker et al, 2009) represent
the average intensity along the line of sight through the heliosheath, Cassini ENA
intensities may be converted to ion fluxes, thus providing a continuous heliosheath ion
spectrum 5 -¤ E -¤ 4000 keV. This conversion yields an estimate of the thickness
of the heliosheath (~ 50 AU) and the local pressure (~ 0.13 pPa). Based on the
ordering of ENA intensities in galactic coordinates, it is hypothesized that the local
interstellar magnetic field plays an important role in determining the shape of the
heliospheric cavity. The results will be discussed in the context of previous and evolving
models.
References
Krimigis et al, Science, 326, 971, 2009
McComas et al, Science, 326, 959, 2009
Decker et al, Solar Wind 12, 25 June, 2009 |
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