IRC+10216’s Innermost Envelope — The eSMA’S View

Abstract

We used the Extended Submillimeter Array (eSMA) in its most extended configuration to investigate the innermost circumstellar envelope (CSE) of IRC+10216 where acceleration of gas and dust due to strong stellar radiation is taking place. We imaged the CSE using HCN and other molecular lines with a beam size of 0”.22×0”.46 arcsec, deeply into the very inner edge (~15 R_*) of the envelope where the expansion velocity is only ~3 km s^(−1). HCN maser components are spatially resolved for the first time on an astronomical object. We identified two discrete regions in the envelope: a region with a radius of ≤ 15R_*, where molecular species have just formed and the gas has begun to be accelerated, and a shell region with a radius of ~23 R_*. These two regions may have emerged because the size distribution of the dust particles are significantly different in these regions. The position angle of the most copious mass loss direction was found to be ~120 ± 10 degrees. In this paper, we summarize some of the highlights of this observational study.