First Detection of the SiO ( v = 3, J = 2–1) Maser Emission from χ Cygni

Abstract

From the simultaneous observations of SiO v ¼ 3, J ¼ 2Y1 and J ¼ 3Y2 masers, SiO v ¼ 3, J ¼ 2Y1 maser emission was detected for the first time toward the S-type Mira variable
Cyg. The line was a single spike and was redshifted with respect to the stellar velocity. The SiO v ¼ 3, J ¼ 3Y2 maser emission was not detected from this star. However, for the O-rich Mira variable TX Cam, SiO v ¼ 3, J ¼ 3Y2maser emission was detected, while v ¼ 3, J ¼ 2Y1 maser was not detected. Two possible line overlaps were adopted as an explanation of these observational results.