[Previous] | [Session 25] | [Next]
Kazunori Ishibashi (NAS/NRC at LASP/GSFC)
The super-massive star \eta Carinae exhibits periodic variations of ~ 85-day in hard X-rays and 2020-day throughout its EM spectrum. Although a number of qualitative hypotheses have been made to suggest the nature of the periodic phenomena, the truth has not yet been identified.
Recent debates on the nature of \eta Carinae's periodicities focus on two types of models: a single, unstable star versus a massive binary system. The main theme of my dissertation addresses quantitatively whether a certain type of a binary hypothesis agrees with the observed changes monitored with RXTE/PCA and HST/STIS observations of \eta Carinae before and after the last dramatic spectroscopic variations occurred at the year 1998.0. The analyses suggest that a binary hypothesis can indeed be fit to explain the periodic variations, while numerous problems with the current binary orbital parameters exist. Therefore, this dissertation does not constitute a proof to a binary hypothesis; there may be a remote possibility that the hypothesis could even be wrong. Further quantitative analysis will be given to illustrate the general problems with a binary hypothesis in order to provide a sense of direction to which future research on \eta Carinae should lead.
This research was supported by NASA grant NAS5-32490 and GO-7402 from the Space Telescope Science Institute.