University of Kansas

X-Ray Emission in the Solar System

Image: Jovian soft X-rays from ROSAT; courtesy of J. H. Waite.


Temporal and Spatial Variations of Heliospheric X-Ray Emissions Associated with Charge Transfer of the Solar Wind with Interstellar Neutrals

I. P. Robertson,1 T. E. Cravens,1 and S. Snowden2
1University of Kansas, Department of Physics and Astronomy, Lawrence, KS 66045
2NASA Goddard Space Flight Center, Greenbelt, MD 20771

(The final version of this paper appeared in Solar Wind 10, Proc. 10th International Conference on Solar Wind, edited by M. Velli, R. Bruno, and F. Malara, AIP, p. 815, 2003.)

Abstract. X-rays should be generated throughout the heliosphere as a consequence of charge transfer collisions between heavy solar wind ions and interstellar neutrals. The high charge state solar wind ions resulting from these collisions are left in highly excited states and emit extreme ultraviolet or soft X-ray photons. X-rays should also be generated because of charge transfer collisions with neutral hydrogen in the Earth's geocorona. Originally a simple model was developed in which both the solar wind and the interstellar neutrals were assumed to be spherically symmetric and time independent. In our updated results, the hot model of Fahr (1971) was used to model spatial variations of interstellar helium and hydrogen. At the same time a simple model was created to simulate X-ray radiation due to the Earth's geocorona. With the updated information, time independent maps of the heliospheric X-ray emission across the sky were created. Measured time histories of the solar wind proton flux were used in this updated model and the results were compared with "long-term enhancements" in the soft X-ray background measured by ROSAT for the same time period.

Acknowledgments. NASA Planetary Atmospheres grant NAG5-4358 and NSF grant ATM-9815574 at the University of Kansas are gratefully acknowledged.

Last modified Oct. 3, 2005
Tizby Hunt-Ward