Thesis

Charge exchange investigation through line emission and comet - solar wind interaction morphology

X-ray analysis of solar system objects lead to the discovery of X-rays from comets in the 1990's. With this discovery it was soon realized that of the variety of ways X-rays are produced, charge exchange is the dominant process at least in the X-ray production from comets. Charge exchange has shown to be an active process in more solar system and astrophysical objects, and models are continually updated. Charge exchange presence in early X-ray studies of comets sparked investigation into the morphology of solar wind comet interaction; through magnetohydrodynamic modeling and the prediction a bow shock would form and be observable in X-ray emission. Presented in this thesis is the search for new cometary X-ray emission lines in the 1000 - 2000 keV range, and tomography searching for cometary X-ray bow shocks using a sample of 5 comets observed with Chandra X-ray Observatory. The surveyed comets are: C/1999 (Linear S4), C/1999 T1 (McNaught-Hartley), 153P/2002 (Ikeya-Zhang), 2P/2003 (Encke), and C/2000 8P (Tuttle). I modeled the spectra with an extended version of a solar wind charge exchange (SWCX) emission model and a model of emission lines at fixed energies. I discovered new emission lines from Ikeya Zhang at 1350, 1740, 1840 and 1950 eV that I identify as being created by solar wind charge exchange with Mg XI, Si K, Si XIII, and Si XIV, respectively. The Mg XI line is significant in the spectra of other comets: Linear S4, McNaught-Hartley, and Encke, but only marginally detected for comet 8P. The silicon lines in the 1700 to 2000 eV range are detected for all comets at a significant level. My detection of Solar wind ions of magnesium and silicon, also previously report at soft X-ray energies (< 300 eV) and these will be useful diagnostic for improved charge exchange models. The detection of possible X-ray bow shock for several comets is also presented.

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