He I Instabilities Observed in eta Carinae Near Periastron

During the 2014 periastron passage of eta Carinae, it was noticed that the neutral helium lines in the optical showed evidence of instabilities from the wind-wind collision region in the P Cygni absorption troughs. We have collected new data with the CTIO 1.5 meter telescope and CHIRON spectrograph during the 2020 periastron. We have compared these new data with data from the previous two periastrons to compare the variations and understand if the instabilities are inherently repeatable. While we see an increase in absorption in the 2020 data, the depth and characterization of the variability is different than the 2014 periastron passage, consistent with long-term variability discussed recently in the literature.

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.