[Solar System -- Oral ]

Chandra Studies of Planets and Comets in the X-ray

Carey Lisse, Johns Hopkins University Applied Physics Laboratory
A. Bhardwaj (Vikram Sarabhai Space Centre), S. J. Wolk (CXC), D. J. Christian (CSUN), K. Dennerl (MPE), D. Bodewits (GSFC), T.H. Zurbuchen (UMich)

The discovery of high energy x-ray emission in 1996 from C/1996 B2 (Hyakutake) created a new class of solar system x-ray emitting objects [1]. Subsequent detections of the morphology, spectra, and time dependence of the x-rays from more than 20 comets have shown that the very soft (E < 1 keV) emission is due to a charge-exchange interaction between highly charged solar wind minor ions and the comet's extended neutral atmosphere [2,3]. Several other solar system objects are now known to shine in the X-ray, including Venus, Mars, the Moon, the Earth, Jupiter, and Saturn, with total power outputs on the MW - GW scale [4]. Like comets, the X-ray emission from the Earth's geo-corona, the Jovian aurora, and the Martian halo are all driven by charge exchange between highly charged minor (heavy) ions in the solar wind and gaseous neutral species in the bodies' atmosphere. The first soft X-ray observation of Earth’s aurora by Chandra shows that it is highly variable, and the Jovian aurora is a fascinating puzzle that is just beginning to yield its secrets. The non-auroral X-ray emissions from Jupiter, Saturn, and Earth, and those from disks of Mars, Venus, and the Moon are mainly produced due to scattering of solar X-rays We present a summary of recent planetary and cometary observations by the Chandra, CHIPS, EUVE, ROSAT, Swift, and XMM spacecraft, in conjunction with solar wind measurements made by the ACE, IMP-8, SOHO, and TRACE spacecraft, in order to demonstrate the richness and utility of solar system x-ray emission.References[1] C.M. Lisse et al., Science 274, 205 (1996)[2] R. Wegmann and K. Dennerl, A&A 430, L33 (2005)[3] D. Bodewits et al., A&A 469, 1183 (2007)[4] A. Bhardwaj et al., PSS 55, 1135 - 1189 (2007)