Solar System - Jovian Planets
X-ray studies of Jupiter's auroral zones near the north and south poles, where the X-ray emission is most intense, offer a probe of JupiterÕs magnetosphere (see the review by Bhardwaj and Gladstone 2000). Chandra and XMM-Newton data show that this auroral emission is due to the precipitation of highly ionized oxygen and either sulfur (favored by Chandra) or carbon (favored by XMM-Newton) into the polar regions (Horanyi et al. 1988; Cravens et al. 1995, 2003); the ionization states and the line characteristics provide information on the electric fields, thus probing the polar magnetosphere dynamics. Oscillations in the northern auroral flux observed in December 2000 (Gladstone et al. 2002) are likely associated with the energetic particle flux in the outer disk magnetosphere and with quasiperiodic radio bursts from Jupiter (McKibben, Simpson and Zhang 1993; MacDowall et al. 1993; Karanikola et al. 2004). More detailed observations of these oscillations and the conditions under which they appear would further constrain the dynamics of JupiterÕs polar magnetosphere.
Chandra observations of Saturn found variations in the averaged X-ray flux of a factor of ~4 over one week (Bhardwaj et al. 2005b) that appeared closely tied to the incident solar X-ray flux. In addition, on timescales of ~0.5 hour, an X-ray "flare" from Saturn was closely linked to the eruption of a solar X-ray flare. The same observations showed emission from the south polar cap and an emission line probably due to oxygen Kα fluorescence from the rings. These new objects are faint X-ray sources, and detailed investigation of their X-ray properties require the high-throughput and high-energy resolution provided by Constellation-X.
