Speaker: Dr. Daniel Tafoya

Institute:
　  Department of Physics and Astronomy, Graduate School of Science and Engineering, Kagoshima University
keywords:
　  planetary nebulae, post-AGB star, IRAS 17347–3139, mass loss,outflows

Time:
　  10:00AM, May 5（Wednesday）, 2010
Location:
　  Middle conf. room, 3rd floor

Abstract:
　  In order to better understand the formation of asymmetric structures in  planetary nebula,we have studied two of the three planetary nebulae that  are known to harbor water maser emission:  K 3-35, IRAS 17347-3139.  These objects show a clear bipolar morphology with a narrow waist;  the water maser emission arises from the central region and in the case of  K 3-35 it is also found located at the surprisingly large distance of ~4000 AU from the central star (near the tips of thebipolar lobes).

　  Several mechanism have been proposed to explain the bipolar morphology of PNe; in the case of K~3-35 we believe that we may be observing some of them at the same time: i) a disk-like structure traced by the H2O masers,ii) a precessing bipolar jet probably due to the presence of a binary companion and iii) circular polarization in the OH 1665 MHz masers, which suggests the presence of a magnetic field. A detailed modeling of all these observational results might shed light on the formation of asymmetrical structures in planetary nebula. On the other hand, we also present the first high angular images of the ionized gas (in radio continuum at lambda=3.6, 1.3 and 0.7 cm)  of  IRAS　17347-3139. The results support the presence of a collimated wind which  might be shaping the bipolar lobes. Additionally, the 0.7 cm images show an equatorial structure that has been interpreted as a high density ionized  torus  in which the water maser emission would be arising.