The Na D lines for eta Carinae are complicated, showing multiple components from the Great Eruption, the second eruption, and stellar winds. Ground-based data obtained over the periastron passages in both 2009 and 2014 showed drastic variability of the component at -145 km/s and related to the Little Homunculus at times near periastron. During the 2020 periastron, this component has disappeared completely, consistent with other long-term trends observed. Once we removed telluric lines, we found a new absorption component for these lines at +86 km/s. This velocity is unusual with its positive component. We report on its variability and suggest possible origins in this presentation. Some comparisons with ultraviolet absorption lines are also presented.
This research was supported through both Embry-Riddle Aeronautical University’s Faculty Innovative Research in Science and Technology (FIRST) Program and HST-GO Programs 15611 and 15992.