Simultaneous observations of SiO and H_2O masers toward known stellar SiO and H_2O maser sources. I.

摘要

We present the results of simultaneous observations of both SiO and H _2O masers toward 166 known SiO and H_2O maser sources using the Korean VLBI Network Yonsei 21 m radio telescope during 2009 June. Both SiO and H_2O maser emission were detected from 112 sources giving a detection rate of 67% at one epoch observation. SiO-only maser emission was detected from 42 sources, while H_2O-only maser emission was detected from four sources. Most of the SiO masers appear around the stellar velocity, while H_2O masers show different characteristics compared with SiO masers. There are more than 20 sources that show a one-way peak or double peaks with respect to the stellar velocity and SiO maser peak velocity. The H _2O maser peak and integrated intensity ratios with respect to those of SiO (v = 1) show increasingly larger values from Mira variables, to OH/IR stars, to semi-regular variables. In addition, the IRAS two-color diagram of SiO and H_2O maser observational results is discussed.