Korean VLBI Network (KVN)
2015 Seminar List:
[06/12/2015] Mr. Gwanjeong Kim (TRAO/UST)
- Dr. Youngjoo Yoon (KVN Group)
- VLBI Observation of the J=1-0, v=1 and v=2 SiO Masers around the Evolvoed Star WX Psc with KaVA
We present the results of simultaneous observation of the J=1-0, v=1 and v=2 SiO maser lines emitted around a long period OH/IR star, WX Psc. This observation was carried out for about 8 hours on 2012 April 1 and the first one performed at Q band towards the late-type star using KVN and VERA array (KaVA). The combined array of KaVA provides a good U-V coverage with various baseline lengths, from 305 km to 2270 km, which is suitable to detect the extended maser feature. The synthesized beam size of KaKA for WX Psc at 43 GHz is about 0.65 mas x 0.56 mas, which is enough to observe the distribution of the compact SiO maser spots emitted from the inner region of the circumstellar envelope. The relative location of the v=1 SiO maser emission with respect to the v=2 SiO maser emission is very useful to investigate the pumping mechanism of these masers. We found the relative coordinates of the v=1 SiO maser spots with respect to the v=2 SiO maser spots by transferring the calibration-solutions of the v=2 SiO maser dataset to the v=1 SiO maser dataset. Our results show that the overall distribution of the v=1 SiO maser emission is very similar to that of the v=2 SiO maser emission, and there is small spatial difference between the two SiO maser emissions. The ring-like structure and the clumpy distribution of the SiO masers are also clearly seen around WX Psc in our results.
Survey of Outflow Activities in Very Low Luminosity Objects
The Very Low Luminosity Object (VeLLO) is a very faint (Lint <=0.1 Lsun) object deeply embedded in dense molecular clouds and believed to be either a very faint protostar or a proto-brown dwarf. To identify and understand the VeLLOs, we have conducted a systematic search for molecular outflow activities in 73 VeLLOs at the rotational transitions 2-1 and 3-2 of CO molecules with SRAO, CSO, and ASTE radio single dish telescopes. In this talk, we will report the preliminary results of this survey and discuss the properties of outflows and the implication of them in the formation processes of low-mass or substellar objects.