X rays from solar wind charge exchange at Mars: A comparison of simulations and observations

Geophysical Research Letters (Impact Factor: 4.46). 01/2004; 31(22). DOI: 10.1029/2004GL020953

ABSTRACT A hybrid simulation of the solar wind-Mars interaction and a test particle simulation of heavy ion trajectories near Mars are used to compute the contribution from solar wind charge exchange processes to the X-ray emission from Mars. It is found that the X-ray halo observed by the Chandra X-ray observatory can be explained by emissions from heavy, highly charged, ions in the solar wind undergoing charge exchange collisions in the upper atmosphere of Mars.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A hybrid simulation of the solar wind–Mars interaction and a test particle simulation of heavy ion trajectories near Mars are used to compute the contribution from solar wind charge exchange processes to the X-ray emission from Mars. Here, we study how the simulated X-ray emissions depend on the parameters of the simulation model. Solar wind parameters are estimated using a ballistic model based on data from the WIND satellite and using an MHD model that uses inputs from interplanetary scintillation measurements. These two models produce X-ray images with significantly different structure. The intensity of the X-ray emissions and the size of the X-ray halo are also found to increase with an increasing exobase neutral temperature.
    Advances in Space Research 01/2005; DOI:10.1016/j.asr.2005.06.007 · 1.24 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In this paper, we estimate the X-ray emission from close-in exoplanets. We show that the Solar/Stellar Wind Charge Exchange Mechanism (SWCX) which produces soft X-ray emission is very effective for hot Jupiters. In this mechanism, X-ray photons are emitted as a result of the charge exchange between heavy ions in the solar wind and the atmospheric neutral particles. In the Solar System, comets produce X-rays mostly through the SWCX mechanism, but it has also been shown to operate in the heliosphere, in the terrestrial magnetosheath, and on Mars, Venus and Moon. Since the number of emitted photons is proportional to the solar wind mass flux, this mechanism is not very effective for the Solar system giants. Here we present a simple estimate of the X-ray emission intensity that can be produced by close-in extrasolar giant planets due to charge exchange with the heavy ions of the stellar wind. Using the example of HD~209458b, we show that this mechanism alone can be responsible for an X-ray emission of $\approx 10^{22}$~erg~s$^{-1}$, which is $10^6$ times stronger than the emission from the Jovian aurora. We discuss also the possibility to observe the predicted soft X-ray flux of hot Jupiters and show that despite high emission intensities they are unobservable with current facilities.
    01/2015; 799(2):L15. DOI:10.1088/2041-8205/799/2/L15
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We analyze the ROSAT PSPC soft X-ray image of the moon taken on 29 June 1990 by examining the radial profile of the surface brightness in three wedges, two 19 degree wedges (one north and one south) 13–32 degrees off the terminator towards the dark side and one wedge 38 degrees wide centered on the antisolar point. The radial profiles of both the north and the south wedges show significant limb brightening that is absent in the 38 degree wide antisolar wedge. An analysis of the soft X-ray intensity increase associated with the limb brightening shows that its magnitude is consistent with that expected due to solar wind charge exchange (SWCX) with the tenuous lunar atmosphere based on lunar exospheric models and hybrid simulation results of solar wind access beyond the terminator. Soft X-ray imaging thus can independently infer the total lunar limb column density including all species, a property that before now has not been measured, and provide a large-scale picture of the solar wind-lunar interaction. Because the SWCX signal appears to be dominated by exospheric species arising from solar wind implantation, this technique can also determine how the exosphere varies with solar wind conditions. Now along with Mars, Venus, and Earth, the moon represents another solar system body at which SWCX has been observed.
    The Journal of Geophysical Research Planets 07/2014; 119(7). DOI:10.1002/2014JE004628 · 3.44 Impact Factor