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Lisse C. M. Dennerl K. Englhauser J. Trümper J. Marshall F. E. Petre R. Valinia A. Kellett B. J. Bingham R. 《Earth, Moon, and Planets》1997,77(3):283-291
The discovery of X-ray emission from comets has created a number of questions about the physical mechanism producing the radiation.
There are now a variety of explanations for the emission, from thermal bremsstrahlung of electrons off neutrals or dust, to
charge exchange induced emission from solar wind ions, to scattering of solar X-rays from attogram dust, to reconnection of
solar magnetic field lines. In an effort to understand this new phenomenon, we observed but failed to detect in the X-ray
the very dusty and active comet C/Hale-Bopp 1995 O1 over a two year period, September 1996 to December 1997, using the ROSAT
HRI imaging photometer at 0.1–2.0 keV and the ASCA SIS imaging spectrometer at 0.5–10.0 keV. The results of our Hale-Bopp
non-detections, when combined with spectroscopic imaging 0.08–1.0 keV observations of the comet by EUVE and BeppoSAX, show
that the emission has the same spectral shape and strong variability seen in other comets. Comparison of the ROSAT photometry
of the comet to our ROSAT database of 8 comets strongly suggests that the overall X-ray faintness of the comet was due to
an emission mechanism coupled to gas, and not dust, in the comet’s coma.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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