First terrestrial soft X-ray auroral observation by the Chandra X-ray Observatory

Space Physics Laboratory, Vikram Sarabhai Space Centre, Trivandrum 695022, India.; Department of Space Science, Southwest Research Institute, San Antonio, TX 78228, USA; Department of Physics and Technology, University of Bergen, Bergen N-5007, Norway; Department of Atmospheric, Oceanic, & Space Sciences, University of Michigan, Ann Arbor, MI 48109, USA; Department of Physics & Astronomy, University of Kansas, Lawrence, KS 66045, USA; University of Alabama in Huntsville, NSSTC, XD12, Huntsville, AL 35805, USA; Jet Propulsion Laboratory, Pasadena, CA 91109, USA
Journal of Atmospheric and Solar-Terrestrial Physics (Impact Factor: 1.75). 01/2007; DOI: 10.1016/j.jastp.2006.07.011
Source: arXiv

ABSTRACT Northern auroral regions of Earth were imaged with energetic photons in the 0.1–10 keV range using the High-Resolution Camera (HRC-I) aboard the Chandra X-ray Observatory at 10 epochs (each duration) between mid-December 2003 and mid-April 2004. These observations aimed at searching for Earth's soft () X-ray aurora in a comparative study with Jupiter's X-ray aurora, where a pulsating X-ray “hot-spot” has been previously observed by Chandra. The first Chandra soft X-ray observations of Earth's aurora show that it is highly variable (intense arcs, multiple arcs, diffuse patches, at times absent). In at least one of the observations an isolated blob of emission is observed near the expected cusp location. A fortuitous overflight of DMSP satellite F13 provided SSJ/4 energetic particle measurements above a bright arc seen by Chandra on 24 January 2004, 20:01–20:22 UT. A model of the emissions expected strongly suggests that the observed soft X-ray signal is bremsstrahlung and characteristic K-shell line emissions of nitrogen and oxygen in the atmosphere produced by electrons.

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