Hirokazu KATAZA

SPICA Science Conference from Exoplanets to Distant Galaxies: SPICA's New Window on the Cool Universe (June 18-21, 2013. Ito Hall, the University of Tokyo), Bunkyou-ku, Tokyo, JapanWe present a result of high-resolution 30 μm imaging observations of the Homunculus Nebula of Eta Carinae (η Car). The Homunculus Nebula is known to contain a large amount of cool dust (approximately 100 K) at polar lobes and a equatorial torus. While the distribution of the cool dust shows the past dust formation events on Car such as giant eruptions and binary interactions, no spatially resolved images at long mid-infrared wavelengths (30-50 μm) have been obtained. We observed Car with a mid-infrared camera MAX38 on the University of Tokyo Atacama 1.0-m telescope, and successfully obtained spatially resolved images of the Homunculus Nebula at 18.7, 31.7 and 37.3 μm. The observations revealed the structure of the massive equatorial torus which contains the dust of 0.09 solar mass. This amount is equal to approximately 80% of the total dust mass 0.12 solar mass in the Homunculus Nebula. It is also found that the dust of 0.012 solar mass exists inside the polar lobes. Assuming that the dust was constantly formed after the giant eruption occurred in 1843, the dust formation rate is estimated as 7 × 10(exp -5)solar mass yr(exp -1). This indicates that the binary interaction plays a significant role in the dust formation on Car.Number of authors: 29Physical characteristics: Original contains color illustrations