Presentation #111.03 in the session Stellar Atmospheres, Winds.
We want to better understand the formation and behavior of small-scale structures in the atmosphere of O-type stars by tracking the changes in ionization lines over a small period of time. We utilized archival Hubble STIS data of O-type star Zeta Ophiuchi available on the MAST database. Of the available STIS echelle modes, we chose E140M, a mode within the high-resolution FUV region, to utilize for this investigation. We performed the x1d function of CALSTIS-6 to extract flux calibrated 1D data for each observation session. Each observation session had multiple associations, which are multiple exposures taken during the same observation session. For each association, we plotted the S/N against the wavelength to ensure the data was usable. As much of the data was above a S/N ratio of 10, with most of it greater than 20, the data was deemed usable. After this, we made a list of 15 ions typically found in very hot stars, such as He II and N V, and will choose from this list specific lines in the UV range 1200-1700 Angstroms. Once specific ionization lines have been chosen, we will plot the associations for each observation and each chosen line on a single S/N plot so that we can track the changes over the length of the observation session.