Observations of SiO ( v = 0, 1, 2) J = 3–2 and J = 2–1 Emission in Late‐Type Stars

Abstract

Observations of SiO v = 0, 1, 2, J = 3-2 transitions were carried out for 42 late-type stars containing SiO v = 1, J = 2-1 maser emission with the 14 m radio telescope at Taeduk Radio Astronomy Observatory (TRAO) during 1995 February and 1996 February. Observations of the v = 0, 1, 2, J = 2-1 transitions in the same objects were performed within 40 days of the former observations using the same telescope. For SiO v = 1, J = 3-2 masers, the line was detected in 23 stars giving a detection rate of 55%. Seventeen of them were new detections. For SiO v = 2, J = 3-2 masers, the line was detected in seven stars, four of them being new detections. The v = 2, J = 3-2 line intensities were found at the expected intensity, unlike the anomalously weak emission seen previously in the rare v = 2, J = 2-1 maser. We also report the intensity ratios observed within the vibrational and rotational states.