Complex Structure of η Carinae in the Mid-Infrared

Abstract

We report high angular resolution observations of complex mid-infrared (4.8-18 μm) structure in the η Carinae Nebula. This massive (~120 Msolar), luminous star is surrounded by a large bipolar nebula extending as much as ~22" in the mid-infrared. Our observations reveal the presence of several condensations within the complex core known as the Homunculus, as well as what may be a toroidal structure visible at 18 μm. This structure may be related to a similar torus seen at near-infrared wavelengths. Our high angular resolution photometry reveals for the first time the spatial variation of the silicate feature in the nucleus of the η Car Nebula. Finally, we present the first high-resolution mid-infrared color-temperature and optical depth maps for the nebula and discuss their significance in relation to the origin of the emission and evolutionary status of the star.