THE ION-INDUCED CHARGE-EXCHANGE X-RAY EMISSION OF THE JOVIAN AURORAS: MAGNETOSPHERIC OR SOLAR WIND ORIGIN?

Yawei Hui,Phillip C Stancil,Vasili A Kharchenko,Thomas E Cravens,Carey M Lisse,Alexander Dalgarno,David R Schultz

doi:10.1088/0004-637x/702/2/l158

Abstract

A new and more comprehensive model of charge-exchange induced X-ray emission, due to ions precipitating into the Jovian atmosphere near the poles, has been used to analyze spectral observations made by the Chandra X-ray Observatory. The model includes for the first time carbon ions, in addition to the oxygen and sulfur ions previously considered, in order to account for possible ion origins from both the solar wind and the Jovian magnetosphere. By comparing the model spectra with newly reprocessed Chandra observations, we conclude that carbon ion emission provides a negligible contribution, suggesting that solar wind ions are not responsible for the observed polar X-rays. In addition, results of the model fits to observations support the previously estimated seeding kinetic energies of the precipitating ions (~0.7-2 MeV/u), but infer a different relative sulfur to oxygen abundance ratio for these Chandra observations.

Highlights

Since the first generation of X-ray observatories, Jupiter has been one of the primary solar system objects of interest
If the solar wind played an important role as a source of ions leading to the CX driven X-ray emission near the Jovian poles, carbon should be required to account for the observed spectra, because apart from the dominant components of the solar wind, hydrogen and helium that do not contribute to the X-ray emission, oxygen and carbon are the most abundant X-ray producing species
Since our model shows no improvement to the fit to Chandra observations by including carbon we conclude that ions of magnetospheric origin are dominant in driving this X-ray emission

Summary

Introduction

Since the first generation of X-ray observatories, Jupiter has been one of the primary solar system objects of interest. Since oxygen ions contributing to the Jovian X-ray auroras could originate either in the vicinity of Jupiter or from the solar wind, the level of discrimination between these two possible sources was provided by including sulfur ions because of their great magnetospheric abundance. This was enabled by the advent of large scale atomic collision and structure calculations, and recently included in the CX model (Kharchenko et al 2006, 2008).

Ion-induced charge-exchange emission model

Spectral Fitting

Discussion