Year: 2012
Type: article
Abstract: We present a new model for the behavior of scattered time-dependent, asymmetric near-UV emission from the nearby ejecta of η Car. Using a three-dimensional (3D) hydrodynamical simulation of η Car's binary colliding winds, we show that the 3D binary orientation derived by Madura et al. in 2012 is capable of explaining the asymmetric near-UV variability observed in the Hubble Space Telescope Advanced Camera for Surveys/High Resolution Camera F220W images of Smith et al.. Models assuming a binary orientation with i ≈ 130°–145°, ω ≈ 230°–315°, P.A. z ≈ 302°–327° are consistent with the observed F220W near-UV images. We find that the hot binary companion does not significantly contribute to the near-UV excess observed in the F220W images. Rather, we suggest that a bore-hole effect and the reduction of Fe ii optical depths inside the wind–wind collision cavity carved in the extended photosphere of the primary star lead to the time-dependent directional illumination of circumbinary material as the companion moves about in its highly elliptical orbit.
Authors: Thomas I. Madura, Jose H. Groh
Institution: Max Planck Institute for Radio Astronomy
Language: Basque
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2062682666