EUVE Science Highlights -
September 8, 2000
EUVE Science Highlights -
September 8, 2000
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This science highlight was submitted by Damian Christian of STScI. Based on paper: C. Lisse, D. Christian, K. Dennerl, F. Marshall, R. Mushotzky, R. Petre, and S. Snowden, H. Weaver, B. Stroozas, and S. Wolk, IAU Circular, 2000 July 25.
Using Chandra and EUVE the authors discovered the first direct evidence for X-ray emission from a comet produced by charge exchange between highly ionized solar wind minor ions and and cometary gaseous species in the coma.
Comet C/LINEAR 1999 S4 was by CXO on 14 July 2000 UT (pre-breakup, maximum signal) and again on 01 Aug 2000 UT (post-breakup, minimum signal). The EUVE observations spanned from 11 July 2000 UT to 18 July 2000 UT. Pre-breakup, the comet was detected by CXO with a count of 0.3 cps, a total integral flux of 8-13 erg/sec/cm2 from 0.2-0.7 keV, and a total x-ray luminosity of 6x1014 erg/sec. The EUVE Lexan/B count rate on 14 July was 0.06 cps in 5400 sec, for an equivalent luminosity of 1015 erg/sec at 0.16 keV; this was consistent with the reddish Chandra spectrum, which showed clear signatures of X-ray line emission due to charge exchange between cometary neutrals and solar wind minor ions (e.g., of O and N).