The outer ejecta of Eta Carinae

Abstract

The nebula around Eta Carinae consists of an inner bipolar structure, historically called the Homunculus, and the outer ejecta consisting mainly of a variety of knots of different sizes.They reach out to distances of up to 30" or0.3pc from Eta Car. With high-resolution long-slit observations we mapped the outer nebula in order to analyze the global expansion pattern and to model the three dimensional structure of the ejecta. We find very different expansion velocities for the knots of the outer ejecta. In some cases they reach up to values as high as 2000km/s. Typical expansion velocities lie at considerably lower values around 400-600km/s, i.e., they are comparable to the expansion velocities found in the Homunculus. Remarkably, the expansion of the outer ejecta reveals a bidirectional motion pattern, which is consistent with the bipolar structure of the inner nebula. A general overview of the morphology and kinematics of the outer ejecta is given and put into context with the structure and kinematics of the inner part of the nebula, the Homunculus.