Author : Candace Gray
Release : 2015
Genre : Auroras
Kind : eBook
Book Rating : /5 ( reviews)

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Book Synopsis The Effects of Solar Flares, Coronal Mass Ejections, and Co-rotating Interaction Regions on the Venusian 5577 Å Oxygen Green Line by : Candace Gray

Download or read book The Effects of Solar Flares, Coronal Mass Ejections, and Co-rotating Interaction Regions on the Venusian 5577 Å Oxygen Green Line written by Candace Gray. This book was released on 2015. Available in PDF, EPUB and Kindle. Book excerpt: The Venusian 5577.3 Å OI (1S - 1D) (oxygen green line) nightglow emission is known to be highly temporally variable. The reason for this variability is unknown. We propose that the emission is due to electron precipitation from intense solar storms. For my dissertation, I observed the Venusian green line after solar flares, coronal mass ejections (CMEs), and co-rotating interaction regions from December 2010 to April 2015 using the high resolution Astrophysical Research Consortium Echelle Spectrograph on the Apache Point Observatory 3.5-m telescope. Combining these observation with all other published observations, we find that the strongest detections occur after CME impacts and we conclude electron precipitation is required to produce green line emission. We do not detect emission from the 6300.3 Å OI (1D - 3P) oxygen red line for any observation. In an effort to determine the emitting altitude, thereby constraining the possible emission processes responsible for green line emission, and quantify the electron energy and flux entering the Venusian nightside, we conducted analyses of space-based observations of the Venusian nightglow and ionosphere collected by the Venus Express (VEX) spacecraft. We were unable to detect the green line but confirmed that electron energy and flux increases after CME impacts. In order to determine the effect of storm condition electron precipitation on the Venusian green line, we modeled the Venusian ionosphere using the TRANSCAR model (a 1-D magnetohydrodynamic ionospheric model that simulates auroral emission from electron precipitation) by applying observed electron energies and fluxes. We found that electron energy plays a primary role in producing increased green line emission in the Venusian ionosphere. Based on observation and modeling results, we conclude that the Venusian green line is an auroral-type emission that occurs after solar storms with the largest intensities observed after CMEs. Post-CME electron fluxes and energies are sufficient to produce the observed green line intensity with the lack of red line emission. We find that O + e is the greatest contributor to the OI (1S) state and is responsible for the observed green line emission.