Understanding the X-ray flaring from η carinae

Abstract

We quantify the rapid variations in X-ray brightness ("flares") from the extremely massive colliding wind binary η Carinae seen during the past three orbital cycles by the Rossi X-ray Timing Explorer. The observed flares tend to be shorter in duration and more frequent as periastron is approached, although the largest ones tend to be roughly constant in strength at all phases. Plausible scenarios include (1) the largest of multi-scale stochastic wind clumps from the Luminous Blue Variable (LBV) component entering and compressing the hard X-ray-emitting wind-wind collision (WWC) zone, (2) large-scale corotating interacting regions in the LBV wind sweeping across the WWC zone, or (3) instabilities intrinsic to the WWC zone. The first one appears to be the most consistent with the observations, requiring homologously expanding clumps as they propagate outward in the LBV wind and a turbulence-like power-law distribution of clumps, decreasing in number toward larger sizes, as seen in Wolf-Rayet winds. © 2009. The American Astronomical Society. All rights reserved.