Nobeyama Radio Observatory Report: Number 390

Abstract

Simultaneous observations of the (28)SiO v = 0, 1, 2, and 3, J = 1-0 and (29)SiO v = 0 and 1, J = 1-0 transitions for 102 late-type stars were made with a sensitivity of about 2 Jy at the 3 sigma level using the 45 m telescope of Nobeyama Radio Observatory (NRO). SiO maser emission was detected in 83 stars; seven of them being new detections. The v = 3 maser was detected in 12 stars with eight new detections. Most of the v = 3 masers occur at the same radial velocity of the strongest spikes of the v = 1 and 2 masers. Also the (29)SiO v = 0 maser newly was found in six stars. The (29)SiO v = 0 line is stronger and narrower than the (28)SiO v = 0 line, indicating that the (29)SiO line is masing. In most cases, the (29)SiO line shows a single narrow profile (FWHM = 1 to 3 km/s), with peak radial velocities coincident with the stellar velocity derived from OH maser and/or SiO/CO thermal lines within 1 km/s. Therefore, this maser line provides excellent means to measure the stellar velocities of late-type stars. The (28)SiO v = 0, J = 1-0 line was detected in eleven stars, with three new detections.

102終期型星の、(28)SiO v=0,1,2,3,J=1-0と(29)SiO v=0,1,J=1-0遷移状態の同時観測を、野辺山電波観測所の45m望遠鏡を使い、3σレベルで約3Jyの感度で行った。SiOメーザー放射が83の星で検出され、それらの内の7つは新検出であった。v=3メーザーは12の星で発見され、8つは新検出であった。v=3メーザーの多くは、v=1,2メーザーの最も大きな振幅における、同一放射速度でおこる。また新たに6つの星で(29)SiOメーザーv=0を発見した。(29)SiO v=0線は(28)SiO v=0線より強く狭く、これは(29)SiO線がメーザー発信していることを示す。多くの場合、(29)SiO線は1本の狭い形(FWHM=1-3km/s)を示し、1km/s以内で、OHメーザーと、あるいはSiO/CO熱線から出る星速度に一致する、ピーク半径方向速度を有する。したがって、このメーザー線は、終期型星の星速度の測定に優れた手段を提供する。(28)SiO v=0,J=1-0線は11の星で発見され、3つは新発見である。