Simultaneous observations of SiO and H₂O masers toward known stellar SiO and/or H₂O maser sources

Abstract

Abstract. We present the results of simultaneous observations of SiO v = 1, 2, 29 SiO v = 0, J = 1-0 and H2 O 616 − 523 maser lines toward 318 known stellar SiO and/or H2 O maser sources using the Yonsei 21-m radio telescope of the Korean VLBI Network. Toward 166 known SiO and H2 O maser sources, both SiO and H2 O maser emissions were detected from 112 sources giving a detection rate of 67.5 %. On the other hand, toward 152 known H2 O-only maser sources, both SiO and H2 O maser emissions were detected from 62 sources, giving a detection rate of 40.8 %.Characteristics of all observed sources in the IRAS two-color diagram is investigated including their evolutionary sequence and mutual relations between SiO and H2 O maser properties.

KVN Monitoring Observations Toward the Recent Outburst Symbiotic Star V407 Cygni

“…In addition, although the SiO v = 2 maser requires higher excitation temperature than that of the v = 1 maser, the SiO v = 2 intensity of V407 Cyg is always much stronger than that of the v = 1 maser, in contrast to the common Mira variables as shown in Figure 2 and Table 3. The average values of peak intensity ratios of the SiO v = 2 maser to the v = 1 maser are 1.1 (Cho & Kim 2012) and 1.16 (Kim et al 2010) in Mira variables. On the other hand, this value for seven post-AGB stars is 2.47 (Yoon et al 2014).…”

FIRST DETECTION OF 22 GHZ H2O MASERS IN TX CAMELOPARDALIS

“…In particular, the intensity ratios of H 2 O with respect to SiO (v = 1, J = 1-0) masers are very low, ranging from 0.0045 to 0.0077. These intensity ratios are above 0.1 for almost all of AGB stars (Kim et al 2010). Exceptions appear in R Cas and R Leo, which also have very low intensity ratios less than 0.1 at most optical phases.…”