Eta Carinae leaves a curious ladder for us to climb....

A systematic study of the narrow absorption lines formed on the spectrum of Eta Carinae done by Gull, Kober & Nielsen (2006 ApJS 163, 173) listed a most curious series of 35 velocity systems ranging from -122 to -1074 km/s spaced at intervals of 10 to 15 km/s with gaps between. After many years of studying the wind-wind interactions of the central massive binary, we suggest that this velocity series is a record of periastron events extending over several centuries and may provide important clues as to when the two major eruptions occurred.