University of Kansas
X-Ray Emission in the Solar System
Temporal Variations of Geocoronal and Heliospheric X-Ray Emission Associated with the Solar Wind Interaction with Neutrals
by Cravens et al.
|
|
University of KansasX-Ray Emission in the Solar System |
Draft Temporal Variations of Geocoronal and Heliospheric X-Ray Emission Associated with the Solar Wind Interaction with Neutrals by Cravens et al. |
Image: Jovian soft X-rays from ROSAT; courtesy of J. H. Waite.
Our study of the temporal variation of the soft X-ray background supports the identification of the ROSAT/PSPC LTEs with heliospheric X-ray emission produced by the SWCX mechanism, as suggested by Cox [1998] and by Cravens [2000] and/or with the geocoronal X-ray emission produced by the SWCX mechanism, as suggested by Dennerl et al. [1997], Cox [1998], and Freyberg [1998]. We demonstrated that the part of the heliospheric X-ray intensity, observed at Earth, that is associated with interstellar helium has a much greater time variability than does the part associated with interstellar hydrogen.
The geocoronal X-ray intensity associated with the SWCX mechanism has an overall intensity less than the heliospheric intensity for timescales greater than a week or so but has an even greater time variability than the heliospheric helium component. The time response of the geocoronal X-ray source to solar wind variations is very rapid due to the relatively small emission volume [Cox, 1998; Freyberg, 1998]. A more careful calculation of both the geocoronal and the heliospheric X-ray emission should be carried out and should include factors such as how the magnetopause location varies with solar wind conditions, the spatial distribution of the solar wind around the magnetopause (including the cusp region), the correct spatial structure of the interstellar neutral H and He densities, the latitudinal and longitudinal structure of the solar wind, and the variations in the solar wind composition.
 |
Tizby Hunt-Ward tizby@ku.edu |