dense wind of the primary luminous blue variable (LBV) star. The accretion from the equatorial plane might lead to the formation of a polar outflow. We suggest that the polar outflow contributes to the soft X-ray emission during the X-ray minimum; the other source is the shocked secondary wind in the tail. The conclusion that accretion occurs at each periastron passage, every five and a half years, implies that accretion had occurred at a much higher rate during the Great Eruption of $\eta$ Car in the 19th century. This has far reaching implications for major eruptions of LBV stars.'
author:
- Amit Kashi and Noam Soker
title: 'USING X-RAY OBSERVATIONS TO EXPLORE THE BINARY INTERACTION IN ETA CARINAE'
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INTRODUCTION {#sec:intro}
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The $P=5.54 \yr$ ($P =2022.7 \pm 1.3~$d; Damineli et al. 2008a) periodicity of the massive binary system is observed in the entire electromagnetic band (e.g., radio, Duncan & White 2003; IR, Whitelock et al. 2004; visible, van Genderen et al. 2006, Fernandez Lajus et al. 2008; emission and absorption lines, Damineli et al. 1997, 2008a, b; X-ray, Corcoran 2005). The periodicity follows the 5.54 years periodic change in the orbital separation in this highly eccentric, $e \simeq 0.9$, 