University of Kansas
X-Ray Emission in the Solar System
Image: Jovian soft X-rays from ROSAT; courtesy of J. H. Waite.
I. P. Robertson and T. E. Cravens
University of Kansas, Department of Physics and Astronomy, Lawrence, KS 66045, U.S.A.
The final version of this paper was published in Geophysical Research Letters, doi:10.1029/2002GL016740, 2003.
Abstract with link to full article on the AGU website.
Abstract. X-rays are generated throughout the terrestrial magnetosheath as a consequence of charge transfer collisions between heavy solar wind ions and geocoronal neutrals. The solar wind ions resulting from these collisions are left in highly excited states and emit extreme ultraviolet or soft X-ray photons. A model has been created to simulate this X-ray radiation. Published terrestrial exospheric hydrogen distributions and solar wind speed, density and temperature distributions were used in this model. Simulated images were created as seen from an observation point outside the geocorona. The locations of the bow shock and magnetopause are evident in these images. Perhaps this X-ray emission can be used to remotely sense the solar wind flow around the magnetosphere. Since similar X-rays are produced in the heliosphere, the challenge will be, however, to eliminate this background emission.
Acknowledgments. This work was supported by NASA Planetary Atmospheres grant NAG5-11038 and NSF grant ATM-9815574 to the University of Kansas.
|Figure 1. X-ray production rate in the x-z plane. Rates are in eV cm-3 s-1. R is distance from the x-axis in this figure, and D is the radial distance to the subsolar magnetopause. Bow shock and magnetosphere positions are indicated.|
|Figure 2. Image of the X-ray intensity as observed from the Earth's flanks (left panel), and from an observation point 45 deg. from the Earth-Sun axis (right panel), in the equatorial plane. Units are keV cm-2 s-1 sr-1. R and X are coordinates in the image plane. Bow shock and magnetosphere positions are again indicated.|
|Figure 3. Heliospheric X-ray intensities similar to those in Cravens et al. , but using an improved interstellar neutral model and a different a. The look direction is north of the ecliptic plane. A look direction in the plane would increase the linear intensities by a factor of 1.4 [Hodges, 1994]. Day numbers start at Jan. 1, 1996.|
|Figure 4. Closeup of the spiked region of the geocoronal X-ray intensities in Figure 3. The total intensity differs dramatically from the linear intensity due to a much large solar wind flux which compresses the magnetosphere.|