36th DPS Meeting, 8-12 November 2004
Session 18 Outer Planets
Poster I, Tuesday, November 9, 2004, 4:00-7:00pm, Exhibition Hall 1A

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[18.04] Chandra X-ray Observations of Jovian Low-latitude Emissions: Morphological, Temporal, and Spectral Characteristics

A. Bhardwaj, R.F. Elsner (NASA MSFC), G.R. Gladstone (SWRI), T.E. Cravens (U. Kansas), J.H. Waite, Jr. (U. Michigan), G. Branduardi-Raymont (MSSL/UCL), P. Ford (MIT)

Chandra observed X-rays from Jupiter during 24-26 February 2003 for about 40 hours with the ACIS-S and HRC-I instruments. The analysis of Jovian low-latitude “disk” X-ray emissions are presented and compared with the high-latitude “auroral” emissions. We report the first Chandra ACIS-S measured X-ray spectrum (0.3-2 keV) of Jupiter’s low-latitude disk. The disk X-ray emission is harder and extends to higher energies than the auroral spectrum. The temporal variation in the Jovian disk X-rays is on an average consistent with those in the solar X-rays observed by GOES, and TIMED/SEE. Contrary to the auroral X-rays, the disk emissions are uniformly distributed over the Jupiter; no indication of longitudinal dependence or correlation with surface magnetic field strength is visible. Also, unlike the ~40±20-min periodic oscillations seen in the auroral X-ray emissions, the disk emissions do not show any periodic oscillations. The disk spectrum seems to be consistent with resonant and fluorescent scattering of solar X-rays by the Jovian upper atmosphere. Jupiter’s disk is found to be about 50% dimmer in soft X-rays in February 2003 compared that in December 2000, which is consistent with the decrease in solar activity. No evidence of lightning-induced X-rays is seen in the Chandra X-ray data. The Jovian disk spectra observed with Chandra-ACIS is stronger than that observed with XMM-Newton two months later during April 28-29, 2003. The XMM-Newton X-ray image of Jupiter shows evidence of limb darkening on the anti-sunward side as seen from Earth, as well as an asymmetry with respect to the subsolar point: suggesting a solar-driven process.

The author(s) of this abstract have provided an email address for comments about the abstract: Anil.Bhardwaj@msfc.nasa.gov

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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.