Theodore R. Gull, Thomas I. Madura, Jose H. Groh, Michael F. Corcoran
We report new HST/STIS observations that map the high-ionization forbidden
line emission in the inner arcsecond of Eta Car, the first that fully image the
extended wind-wind interaction region of the massive colliding wind binary.
These observations were obtained after the 2009.0 periastron at orbital phases
0.084, 0.163, and 0.323 of the 5.54-year spectroscopic cycle. We analyze the
variations in brightness and morphology of the emission, and find that
blue-shifted emission (-400 to -200 km s-1) is symmetric and elongated along
the northeast-southwest axis, while the red-shifted emission (+100 to +200 km
s-1) is asymmetric and extends to the north- northwest. Comparison to synthetic
images generated from a 3-D dynamical model strengthens the 3-D orbital
orientation found by Madura et al. (2011), with an inclination i \approx
138\degree, argument of periapsis {\omega} \approx 270\degree, and an orbital
axis that is aligned at the same PA on the sky as the symmetry axis of the
Homunculus, 312\degree. We discuss the potential that these and future mappings
have for constraining the stellar parameters of the companion star and the
long-term variability of the system.
View original:
http://arxiv.org/abs/1110.6420
No comments:
Post a Comment